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Title

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THE ADVANCE OF THE FUNGI

Two novels by the same author

SUGAR IN THE AIR ASLEEP IN THE AFTERNOON

THE ADVANCE

OF

THE FUNGI

by

E. C. LARGE

JONATHAN CAPE

THIRTY BEDFORD SQUARE

LONDON

FIRST PUBLISHED 1940 REPRINTED AUGUST 1946

REPRINTFJ) IN GREAT BRITAIN BY

HENDERSON & SPA1-OINC, LONDON, W.I

HOUND BY A. W. BAIN & CO. LTD.

CONTENTS

ACKNOWLEDGMENTS 7

I THE POTATO MURRAIN 1 3

II FAMINE IN IRELAND 34

III OIDIUM ON THE VINES 44

IV FRUITS OF THE FUNGI 56

V THE BUNT OF THE WHEAT 70

vi VEGETABLE PATHOLOGY' 86

VII OOSPORES AND ZOOSPORES 95

VIII ENTER LOUIS PASTEUR 104

IX THE BARBERRY AND THE WHEAT 121

X SCHOOL FOR PLANT DOCTORS 137

XI PHYLLOXERA OF THE VINES 147

XII THE WATER FUNGI 159

XIII CLUB ROOT AND ANTHRAX 178

XIV CANKER OF THE LARCH 1 88

XV COFFEE RUST IN CEYLON 196

XVI AFTER FORTY YEARS 2O8

XVII BORDEAUX MIXTURE 225

xvin DANISH 'HOT WATER' 240

XIX THE LEAD OF THE U.S.A. 248

XX POTATO SPRAYING 26 1

XXI FUNGI IN THE ORCHARDS 272

XXII WHEAT — SPECIES IN THE MAKING 292 XXHI MICROBES AND MOLECROBES 3 1 3

XXIV CALLING THE CHEMItAL INDUSTRY 324

XXV LEGISLATIVE MEASURES 338

XXVI BLIGHT, WART DISEASE, LEAF-ROLL 346

XXVII FUNGI AND THE GREAT WAR 362

XXVIII DUSTING AND SEED-DISINFECTION 384

XXIX NEW SPRAYS FOR OLD 397

XXX DEGENERATION AND VIRUS DISEASES 415

XXXI TOWARDS IMMUNITY 432 BIBLIOGRAPHY 451 INDEX 477

A C K N O W LEDGMENTS

IN the bibliography, which will be found at the end, I have included full particulars of some five hundred of the principal scientific papers, books, and other published writings of the past and present upon which this history is based. The tides of the various publications are indicative of the way in which a science has grown, and with this in mind I have arranged the references for each chapter in chronological order, noted translations into English of books and papers in other languages, and given the starting dates of some of the periodicals which have played a leading part in the story, with the recognized (World List) abbreviations for the names of them. Each of the historic illustrations of the fungi reproduced in the text is subscribed with the author's name and date of first publication. Where the word 'after' appears in the subscript it means that the figure is not a direct mechanical reproduction, but a line-copy that I have made with the assistance of a photograph. The figures without subscript are original.

I am indebted to those in charge of the libraries of the Royal Botanic Gardens at Kew, the Imperial Mycological Institute, the British Museum, the Science Museum, the Linnean, Chemical, and Royal Horticultural Societies, the Patent Office and the Ministry of Agriculture, for unfailing help in my search of the literature, and also to Dr. J. Caldwell, Dr. G. H. Pethybridge and Dr. R. N. Salaman, for the loan of numerous books and papers.

I thank my old friend Dr. E. S. Gyngell for the line drawings of oats in flower and of Wart Disease (Figs. 45 and 55); Dr. W. A. R. Dillon Weston for the original study of Apple Scab (Fig. 48); Dr. R. N. Salaman for per- mission to photograph the Blight-resistant potato plants (Plate VI); the Controller of H.M. Stationery Office for permission to reproduce the illustration of Potato Leaf Roll from the Ministry of Agriculture and Fisheries' Advisory Leaflet No. 278 (Plate V, c); and the Royal Dublin Society for permission to reproduce Figs. 53 and 54.

Finally I would express my warmest thanks to both Dr. G. H. Pethybridge, late Mycologist to the Ministry of Agriculture and Fisheries, and Dr. G. R. Bisby, formerly Professor of Plant Pathology at Manitoba University, for their very great kindness in reading the whole book in typescript and giving me their unstinted help in the work of correction before going to press.

September 1940 E. C. LARGE

Trace Science then, with Modesty thy guide;

First strip off all her equipage of Pride;

Deduct what is but Vanity, or Dress,

Or Learning's Luxury, or Idleness;

Or tricks to show the stretch of human brain,

Mere curious pleasure, or ingenious pain;

Expunge the whole, or lop th* excrescent parts

Of all our vices have created Arts;

Then see how little the remaining sum,

Which serv'd the past, and must the times to come!

POPE, Essay on Man, Epistle n, 1733

THE ADVANCE OF THE FUNGI

CHAPTER I

THE POTATO MURRAIN

*A FATAL malady has broken out amongst the potato crop. On all sides we hear of the destruction. In Belgium the fields are said to have been completely desolated. There is hardly a sound sample in Covent Garden Market/ So began the first warning of a calamity, in the editorial columns of The Gardeners9 Chronicle and Agricultural Gazette, on August 23rd, 1845. The potatoes had suffered from diseases in the past: from 'Scab', from a malady called the 'Curl', from drought, and from too much rain in bad seasons, but nothing quite so destructive as this new murrain had ever been seen before. It struck down the growing plants like frost in summer. It spread faster than the cholera amongst men. The Gardeners9 Chronicle, then under the very dis- tinguished editorship of Dr. John Lindley, had published the first report of the appearance of the disease in England — a letter from Dr. Bell Salter in the Isle of Wight — the week before, and now Dr. Lindley was sounding the alarm. His editorial went on: *. . . the disease consists in a gradual decay of the leaves and stem, which become a putrid mass, and the tubers are affected by degrees in a similar way. The first obvious sign is the appearance on the edge of the leaf of a black spot which gradually spreads; the gangrene then attacks the haulms, and in a few days the latter are decayed, emitting a peculiar and rather offensive odour. When the attack is severe the tubers also decay/

There was little optimism in Dr. Lindley 's words; he saw that if this mysterious murrain continued to spread amongst the potatoes, an important part of the country's food supplies for the coming winter would be lost. And he said: 'As to cure for this distemper there is none. One of our corre- spondents is already angry with us for not telling the public hew to stop it; but he ought to consider that Man has no power to arrest the dispensations of Providence. We are visited by a great calamity which we must bear/

As the weeks went on, into September, the reports of the spread of the disease, from Poland, Germany, Belgium, France, and from all over England except a few districts in the north, proved that Dr. Lindley's fears were not exaggerated. Every kind of potato was attacked: the Black Scotch, the Bread Fruit, the Jersey Blues . . . When the potatoes were dug from the ground they were found marked with the dark patches, symptomatic of the disease. The colour of these patches was that of contused flesh, its tints were

13

THE ADVANCE OF THE FUNGI

likened to those accompanying a black eye. Potatoes left on the floor of a barn for a week were found worse than when they were lifted. The disease was spreading amongst the potatoes in the ground and in store, and it was thought that every tuber, no matter how slightly affected, would be lost. A kind of mouldiness which the Rev. M. J. Berkeley had observed to appear on the diseased tubers would add greatly to the mischief by hastening decay.

It was apparent that the peculiar changes of weather which had occurred during the summer of 1845 had much to do with the outbreak and the spread of the Potato Murrain. The season had been very favourable for planting and hoeing, and the appearance of the crops was as promising as could be wished up to the beginning of July. The weather was then hot and dry, the tempera- ture i£ degrees to 4^ degrees above the average for the previous nineteen years. 'In short it was beautiful haymaking weather', wrote a Mr. F. J. Graham — in a prize essay on the history of the murrain, published in the Journal of the Royal Agricultural Society a little later — 'it then suddenly changed to the most extraordinary contrast that I ever witnessed in this fickle climate, the atmosphere being for upwards of three weeks one continued gloom, the sun scarcely ever visible during the time, with a succession of most chilling rains and some fog, and for six weeks the temperature was from i J degrees to 7 degrees below the average for the past nineteen years/

Dr. Lindley's theory was that as a result of such changes in the weather the potato plants had become in some way overladen with water; they had been growing away fast and furiously during the good weather, then when the fogs and the rain came they absorbed moisture with avidity, and in the absence of sunshine transpiration was checked, the plants had been unable to get rid of the excess of water in their usual way, and so they had contracted a kind of dropsy and wet putrefaction had set in. The Rev. M. J. Berkeley, 'a gentleman eminent above all other naturalists of the United Kingdom in his knowledge of the habits of fungi', was of contrary opinion. He had at once connected the potato disease with the prevalence of a kind of mould on the affected tissues, but in Dr. Lindley's view, the eminent Mr. Berkeley, preoccupied with toadstools and mushrooms and moulds and mildews, all the greater and the lesser fungi, was attaching far too much importance to a little growth of mould on the diseased potato plants. It was only to be expected that 'as soon as living matter lost its force, as soon as diminishing vitality took the place of the customary vigour, all sorts of parasites would acquire power and contend for its destruction. It was so with all plants, and all animals, even man himself. First came feebleness, next incipient decay, then sprang up myriads of creatures whose life could only be maintained by

14

THE POTATO MURRAIN

the decomposing bodies of their neighbours. Cold and wet, acting upon the potato when it was enervated by excessive and sudden growth would cause a rapid diminution of vitality; portions would die and decay, and so prepare the field in which mouldiness could establish itself. And thus an evil, in itself too great, would be infinitely increased'.

The Rev. M. J. Berkeley agreed that there was much weight to John Lindley's argument; he advanced his own contrary views with a proper reservation of philosophic doubt, but in fact he had made up his mind and he was not a man to be shaken in his convictions. He not only insisted that the growth of mould on the potato plants was a highly significant pheno- menon, but as soon as he had seen the diseased foliage himself, in his parish, near King's ClifFe in Northamptonshire, he put forward the revolutionary theory that the mould might be the cause and not the consequence of the Potato Murrain.

There was, in Paris, an old surgeon of Napoleon's armies, by name Dr. Montagne, with whom the Rev. M. J. Berkeley was in frequent corre- spondence. On his return from the wars, Dr. Montagne had decided to devote the rest of his life to the peaceful labour of searching out and describ- ing the cryptogamic flora of France. From Dr. Montagne, Berkeley received specimens and sketches of the fungus found associated with the Potato Disease across the Channel. The fringes of mould on the leaves had exactly the same appearance, when examined under the microscope, as those on potato leaves from fields in Northamptonshire. There was the same mould on the diseased potatoes themselves, and though Berkeley had never seen this particular species of mould before, it did resemble in certain respects a mould that he had seen growing on onions and shallots. It also appeared to belong to the same natural order as the fungus which was associated with a very serious disease of silkworms in France and Lombardy . It was a lowly vegetable organism, a minute fungus of the genus Botrytis.

Berkeley had to admit that this particular species of Botrytis, now to be found on the stricken potatoes, was new to science, and it was difficult to see why it should suddenly make its appearance, throughout Europe, in the year 1845. All Berkeley could suggest was that now that the botanists knew what to look for, they would probably find that the same fungus had been flourishing for ages on potatoes in some part of the New World, where the weati er conditions were normally the same as they had been in Europe during the unusual summer of 1845. The Potato Murrain, insisted the Rev. M. J. Berkeley, was due to the growth of this specific fungus, and no other, as a parasite on the potato plants. The humid, grey and wet weather, might

15

THE ADVANCE OF THE FUNGI

have caused the living tissues of the plants to become charged with too much water, though such a thing did not appear to him very likely. It was much more probable that the weather simply favoured the spread of the moisture- loving fungus. In one respect only did the Rev. Mr. Berkeley agree with Dr. Lindley: as the development of the fungus depended entirely upon the weather, it would doubtless be impossible to find a remedy.

Thus began an argument between two learned men, each firm in his own conviction and with weight of reason to support it, on an issue that was in fact much deeper than that of attributing the Potato Murrain to its most pro- bable cause. The issue was the establishment or the rejection of a new con- ception of the nature of Disease, not only in plants, but ultimately in all living things. A grand philosophical controversy was beginning, in which nearly every scientist or natural philosopher in the world would soon be taking sides. In advancing the hypothesis that a living parasitic organism on the potato foliage was the cause and not the consequence of the Potato Disease the Rev. M. J. Berkeley was anticipating the germ theory of Pasteur by nearly a quarter of a century.

There was something rousing about those intellectual passages at arms between Berkeley and John Lindley in the columns of The Gardeners9 Chronicle of 1845 and 1846. John Lindley was not only a man of scientific attainment, professor of botany at University College in London; he was experienced in the practical and commercial cultivation of plants, and he was one of the best fighting journalists in the country. He knew how to give forceful expression to his own views and to defend them against all comers, but as an editor he held the scales fairly. He gave the fullest space and the weightiest consideration to every contribution from the pen of the Rev. M. J. Berkeley, and in addition he published a multitude of observations and speculations from other correspondents, anything and everything that might throw light on the cause and nature of the Potato Murrain. Some of the speculations then seemed sensible and some seemed wild. But they should stand recorded, for future workers to read, and to interpret for themselves in the light of later discoveries. John Lindley was not mistaken in his policy; amongst all the then unrelated facts, the gropings, shrewd guesses and confused notions, there were nearly all the clues.

It seemed a wild notion that a mere mould could be the cause of disease in a living plant. And in truth Berkeley could bring forward little enough of the evidence that would be required for rigorous proof of his contention. It was one thing to state that the mould caused the disease and quite another to show how it could do so. Even if it were established that the mould

16

THE POTATO MURRAIN

always accompanied the rotting and decay, it would be necessary to demon" strate which came first. Until that was done the 'fungal hypothesis* would be a mere notion, unsupported by proof. And which came first, the mould or the decay, the fungus or the disease, was not altogether unlike the ancient conundrum about the chicken and the egg. When it came to argument there was much to be said in favour of the precedence of debility or decay. Was it not common knowledge that the moulds and mildews, like their larger relatives the toadstools and the mushrooms, were generally to be found growing on decaying matter: on rotting horse manure, or dead wood, or stale bread, or the humus in the soil? They were part of Nature's pro- vision for hastening the decomposition of dead organic matter, to render it available for use over again. And in all literature and fable the fungi were quite as much symbolic of pre-existent mortification, as of damp, dark, poison, and miscellaneous principles of evil. It was difficult to believe that they could establish themselves on a healthy green leaf, or on any host that was defended by its own internal forces of vigour and life.

The way in which moulds and mildews sprang up, as it were overnight, and the manner of their reproduction, was also highly mysterious. Although that ingenious Italian, Felice Fontana, had examined the Rust on the wheat under a microscope, as long ago as 1767, and recognized it as a minute vegetable with bodies resembling seeds; and although by 1807 Benedict Prevost in France had actually seen the spores of the Bunt fungus on the wheat germinating like seeds in water, it was still commonly believed that small fungi could be produced in decaying matter by spontaneous generation. It seemed reasonable that such trifling growths could well be brought into being by the heat of putrefaction or the ambient atmosphere without the help of any seminal principle. Men of Dr. Lindley's intellectual calibre had long since rejected the notion of spontaneous generation in its cruder forms: they did not believe that mice could be produced by enclosing a piece of cheese and some old rags in a hat box, or that blow-flies were generated by bad meat; but they were perpetuating the idea, all unconsciously, in attributing the growth of living moulds so readily to fermentative processes of decay caused by pre-existent Disease. Since the time of Lavoisier fermentation had been regarded as a purely chemical process, the decomposition of unstable azotic — or nitrogenous — compounds in the organic material. If living fungi came into being as a result of purely chemical processes, that was spontaneous generation. All kinds of phenomena were being attributed to fermentation, or putrefaction, or decay, in cheerful ignorance of the fact that practically nothing was then known of the nature of fermentative processes themselves.

B 17

THE ADVANCE OF THE FUNGI

As Berkeley was very well aware, the Rust and Bunt of the wheat, which were certainly diseases of that plant, were already regarded by many of the greatest European botanists — Corda, Fries, Leveille, De Candolle amongst others — simply as growths of small fungi. It was quite customary to speak, somewhat loosely, of these particular fungi as the cause of the Rust and the Bunt. The damage they did in no way resembled the new routing away of the potato foliage and tubers. But if small fungi growing on the wheat could be said to cause diseases of the wheat, it was only putting two and two together, to say that another fungus found growing on the potato might be the cause of the new Potato Disease.

The fungal nature of the Rust and the Bunt was, however, by no means universally admitted, even by those few botanists who concerned themselves with the diseases of plants. Franz Unger of Vienna, another army surgeon, and one of the first to maintain a garden of plant diseases for his own instruc- tion and pleasure, had published a very famous work called Die Exantheme der Pfanzen, in 1833. He contended that the growths which other botanists took to be small fungi on the leaves of plants were mere 'exanthemata', or outgrowths from the plants themselves, analagous to those found in eruptive diseases of animals. In consequence of some morbid condition, the plants came out in pustules, or grew fringes of unhealthy down on their leaves and began sporulating. As these outgrowths had organized vegetative forms, he did admit that they might have some individuality, but at most they were 'endophytes', little plants which had their origin within their hosts. Unger did not observe the spawn threads winding about among the leaf cells, or he might have been of a different opinion.

Unger's notions were current and influential even amongst the natural philosophers of 1845; while in the world at large the residues of even stranger beliefs were still extant. An old notion of the origin of mildew, prevalent in Shakespeare's time, was that, in damp localities, sticky or honey-like principles were exhaled from the surface of the earth, to be chilled at night, and to settle on plants as a kind of honey-dew. Hence one of the much-dis- puted derivations of the word 'mildew' by way of the German 'Mehltau or 'meal-dew' from the Gothic 'tnilip9 for honey, plus 'tau or 'dew'. The honey-dew on the plants was supposed to be congealed and corrupted by the subsequent heat of the sun, thus causing disease. As growths of mildew were very common in low-lying, damp localities, such as those in the neighbourhood of water-mills, the word was often written 'Mill-dew'.

In the tacit assumption that was being made by so many people, John Lindley included, that the little Botrytis fungus was growing on the potato

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THE POTATO MURRAIN

plants only in consequence of some antecedent putrefaction, there was much that dated back to the ideas of that grand old early microscopist, Robert Hooke, in his Micrographia of 1667. Hooke was the first man ever to describe the appearance under the compound microscope of a fungus growth on leaves. With the newly invented and marvellous instrument, which he had made with his own hands, Hooke gazed in awe at many things in an undiscovered world. He described what he saw, and set down all his thoughts about his observations, whether others might think them valid, or dismiss them as wrong. He said: 'I have produced nothing here to bind the reader's understanding to an implicit consent/ He hazarded that 'the blue and white and several kinds of hairy spots, which are observable on different kinds of putrify'd bodies' (including decayed leaves of plants) 'are all of them nothing else but several kinds of small and variously-figured mushrooms, which from convenient materials in those putrefying bodies, are by the concurrent heat of the air, excited to a certain kind of vegetation'. He had been looking then at a blue mould on some old leather. But he also examined some Damask-rose leaves which were speckled with yellow stains, and on the underside of them he saw 'yellow hillocks of gummous substance marked with black spots'. Through his microscope he saw L: those hillocks 'multitudes of black cases or bodies like seed cobs'. He saw what he took to be the growth of a minute vegetable, and he ascribed its generation to the action of some gummous or honey-like Mill-dew, which, coming upon the leaves, had caused them to putrefy. He supposed that under the influence of the putre- faction a living part of the rose leaves had gone to the making of the smaller plants he saw. 'So, though the seminal principles from which this minute plant on rose leaves did spring, were, before the corruption caused by the Mill-dew, a component part of the leaf on which it grew, and did serve as a coagent in the production of it, yet might it be so consummate, as to produce a seed which might have the power to propagating the same species.' In other words, leaf organs of the Damask rose had taken a creative initiative in the presence of decay and grown into little mushrooms. The ever-watchful and hard-worked Almighty had blessed this enterprise, and given seeds to the little mushrooms by which they might reproduce themselves, inde- pendently of the whim of the rose.

The doctrine of 'heterogenesis' did not take quite so picturesque a form in 1845, but it was inherent in the notions of those who thought that Berkeley's Tungal hypothesis' was fantastic.

The speculations of natural philosophers about the cause of the Potato Murrain were highly interesting and important, but they sank to triviality

19

THE ADVANCE OF THE FUNGI

before the practical necessity of saving all that could be saved of the year's potato crop, and of conserving seed for the coming season. Nothing was known of the course that the disease would take; the potatoes were rotting in the ground — not everywhere, but in a pestilence so universal why should any be spared? It was suggested that the rot might be caused by static electricity — generated in the atmosphere by the issuing puffs of smoke and steam from the hundreds of railway locomotives that had recently come into use, and for all that was surely known it might equally well be due, as others supposed, to mortiferous vapours or 'miasmas' rising from blind volcanoes in the interior of the earth. Should the potatoes be left in the soil, or dug up, or steeped in preservatives and dried, or exposed to the light, or kept in the dark? Nobody knew.

And then also, Disease was Disease. The Potato Murrain and the cholera were both diseases. To eat the blighted potatoes, however little sign they might show of infection, would perhaps cause cholera in man, and other distempers in beasts. Two thousand tons of potatoes shipped sound from Hull were rotten before they arrived in Belgium. At Erfurt in Germany an outbreak of dysentery was attributed to the bad potatoes. In Ghent market potatoes were seized by the authorities because of the danger of cholera. Poland was already threatened with famine, and there was a report — subse- quently denied — that the Prussian army had been called upon to keep the starving people out of Prussian territory. The diseased potatoes might be as poisonous as ergoted rye; and the suffering that had caused amongst the peasants of Burgundy and Lorraine in 1816 was not forgotten. It was a fungus, Clav iceps purpurea, which blackened and elongated the kernels of the rye in wet seasons; when hunger drove peasants to eat bread made from this bad rye, a terrible form of gangrene was the result. Ergot, through its constrictive action on blood vessels, not only caused abortion in women, it cut off the blood supply to the extremities of the body; hands and feet became devoid of sensation and then rotted most horribly away. In the progress of the ergot gangrene whole limbs fell off at the joints, before the shapeless trunk was released from its torments. *

There was a certain heroism in the action of a Monsieur Bonjean of Chambery, in undertaking to live for three whole days on potatoes blighted by the new murrain. He ate each day eight pounds of partially diseased potatoes and drank eight ounces of the water in which wholly putrid pota* toes had been boiled. The smell of the infusion was abominable and the taste nauseous, but he suffered no ill effects, save indigestion and 'a disagreeable heat oppressing the chest'. The experiment of eating the blighted potatoes

20

THE POTATO MURRAIN

was made of necessity by the labouring classes, without any gratifying lime- light for risks undertaken in the cause of science, and it was soon established that the undecayed portions of the blighted potatoes were wholesome enough. Measures were required to arrest the rot in the tubers or to utilize what was good of them in time. It was proposed that they should be pounded or grated to a pulp and washed with water to extract the grains of starch or potato flour, leaving the fibrous material and brown decayed residue for feeding to the pigs. The starch, or farina, could be baked into bread, and although its extraction was admittedly troublesome, the labouring classes would have a way of providing themselves, by their own industry, with adequate food for the lean time that was coming. In England, the Poor Law Institutions could be used as factories for extracting the potato starch; the labour involved was very suitable for the moral rehabilitation of paupers, and it would cost nothing.

On September ijth there was another dramatic paragraph in The Gardeners9 Chronicle:

'We stop the Press, with very great regret, to announce that the Potato Murrain has unequivocally declared itself in Ireland. The crops about Dublin are suddenly perishing. The conversion of potatoes into flour, by the process described by Mr. Bodingtonin this issue becomes t>f the first national importance; for where will Ireland be, in the event of a universal potato rot?'

Where indeed? Although there was dire poverty in England, and the paupers in Andover workhouse had been reduced to eating the marrow and gristle of green horse-bones that they had been set to break up for manure; although the failure of the potato crop in England would bring gaunt enough distress, it was nevertheless true that the poorest labourer in England lived on oat gruel and bread as well as potatoes. The cereal crops had not failed. In Ireland the cottiers lived almost exclusively on potatoes. If the Potato Murrain spread through the small-holdings of Ireland there would be millions of men, women, and children, who would not merely suffer acute privation, but who would starve to death.

John Lindley had good reason to stop the press. The news would shock those readers who had any imagination or humanitarian feeling; but it was more serious than that. The Irish, despite their pappy diet of potatoes, had never been tanie, and they could be expected to put up a certain fight before they died. There would be rebellions, lootings of landowners' property, even more assassinations, and a general disturbance of the very rickety peace. The interests of the prosperous English gentlefolk, who went in for luxury gardens and subscribed to The Gardeners' Chronicle, were involved. It was the

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THE ADVANCE OF THE FUNGI

wretched, potato-eating, cabin-dwellers of Ireland who paid most of the rent for that land, and dead men, even dead Irishmen in 1846, would pay no rent. The Potato Murrain in Ireland might well cause the gravest incon- venience and even loss to the land-owning classes: already there was a rumour that the shortage of food would give Sir Robert Peel the excuse he was seeking to repeal the Corn Laws. . . .

The literate public in England was well informed about The Condition of the People in Ireland, just before and during the outbreak of the Potato Murrain; there had been a searching inquiry by the Devon Commission in 1843, and it happened that Mr. Thomas Campbell Foster, special commis- sioner for The Times newspaper, was over there, in the summer of 1845, making a tour of the country. Mr. Foster was called to the Bar in the follow- ing year; he had a judicial mind and had recently perfected a new system of shorthand, very useful for the recording of facts. He wrote of the condition of the Irish people without fear or favour. Without favour for the Irish and without fear of the landlords. His style proclaimed him an upright and an honest man, who conceived it his vocation to tell the truth and to fear only God. He was disliked to a degree by both sides, and was ridiculed by Mr. Daniel O'Connor.

Foster's account* of the people amongst whom the Potato Murrain descended, as plague and fire had once descended upon crowded London, was a story of parasitism, of a horrible rent-collecting system, whose hyphae and haustoria, or tentacles and suckers, reached down into every wretched cabin, and drained the substance of the people and the land. The owners of the estates in former times had kept open house, spent their days in hunting and shooting, and lived far beyond their incomes. They had used every means to raise money; incidentally, they had cut down most of the trees in Ireland, and sold the timber, so that the land was a treeless waste. Then they had granted long leases of their land to middlemen, for enhanced rents; thus evading all manorial or feudal responsibility for the welfare of their tenants, and handing the management of the land over to purely mercenary inter- mediaries, whose business it was to subdivide, and make their own profit, from letting the land retail. At every sub-division the rent went up, and the smallest farmers, forced to pay these increased rents, learnt the dodge from their superiors, and again sub-let their land, in roods of 'conacre' at a time to their labourers, or to the 'cottiers', who were the ultimate cells of this social organism. The cottiers lived in their miserable cabins, without chimneys and without windows, and on their quarter-acres of hired land they grew their 'lumpers' — their coarse but prolific potatoes ~ not in ridges but

22

THE POTATO MURRAIN

in so-called 'lazy beds': a primitive method of cultivation, which in fact required much hard work, but was often well adapted to the poorly drained land — especially in the west. On these potatoes they kept body and soul together, and except in the 'meal months' of July and August, the gap between the old potatoes and the new, they often tasted nothing but potatoes and pepper water from one month's end to another. Their stomachs were distended with from eight to fourteen pounds of potatoes per day.

To keep the bit of land on which the potatoes were grown was their desperate necessity. They had to pay the rent. The .£10 or ^£12 per acre was remorselessly sucked up from them and divided between the landowners and the various middlemen. The wages for occasional labour on the estates and farms, and the pig, went to pay the rent. In the cabins there was always a pig; on the less poverty-stricken farms and on the estates, cattle were reared and corn was grown. The pigs, the cattle and the corn made up the wealth of the country, the marketable and exportable produce that went to pay the rents. The cottiers lived on the potatoes, on food inadequate for cattle but good enough for men. From the substance of the potato alone was built up the stuff of human bone, muscle, sperm, and milk for the young.

In one of Mr. Foster's articles in The Times of 1845 a typical annual budget was given for a labourer and his family in Ballinamore, where conditions were by no means so bad as in the extreme west. The man's wages were sixpence a day, and he had casual agricultural employment averaging six months in the year. The rent of his cottage was £2 los. and of his rood of conacre another £2 los. He kept a pig which he could sell for about ^4. And on his rood of conacre he grew, according to Mr. Foster, some five tons of potatoes, giving a ration for himself and his family of thirty-two pounds of potatoes a day over the year. But here Mr. Foster was optimistic; it was almost unbelievable that the cottiers ever obtained anything like a crop of twenty tons of potatoes per acre, and on impoverished land. Apart from the potatoes, this was the annual budget:

£, s- a-

Wages 3 18 o

Value of Pig 400

Deduct Rent 500

Balance .£2 18 o

23

. THE ADVANCE OF THE FUNGI

£2 1 8s. od, per annum, to buy meal, clothing, tools, candles, medicine, drink, and every other luxury or necessity for a human family. While the middlemen and the landowners took the man's pig and a quarter of his wages, it was not difficult to perceive that without the potatoes that family would starve.

The population of Ireland had grown from 4^ million in 1800 to over 8 million in 1845. The fertility of animals was said to rise with partial starvation, perhaps as a natural provision for the perpetuation of species in times of high mortality and danger; and this would seem to have been true of man in Ireland over that half century. But there were many factors favouring the increase. In the crowded cabins only elemental pleasures were free. The Catholic priests blessed the fecundity, for they themselves multi- plied and grew the fatter the more souls they had to save. The 'squireens', the impecunious younger sons of the landowners, sought to create as many 'forty-shilling freeholders' as possible in order to barter their votes with politicians for jobs in the government. The infinite sub-division of the land, the very ease with which potatoes could be grown — everything favoured the increase of population.

Absentee landlords sometimes visited their Irish estates and were amazed at the hordes of haggard, dirty and wretched people that had, as it were, sprung up from nowhere. It was not their affair, but really the Government should do something for these unhappy people. Educate them, shake them out of their habits of idleness, encourage them to better themselves ... If they would only adopt the new methods of agriculture, be a little more ambitious than to grow potatoes year after year on the same land, go in for the rotation of crops, work during the winter at improving their holdings and their dwellings instead of kippering themselves over their turf fires — how much better off they would be ! It was true that any improvement they made was immediately followed by an increase in the rent. But they stood to profit just as much from improvements as did the landowners. How stupid it was of the lower orders to refuse to better themselves, merely because they would have to share their gains with their superiors!

It was impossible to do anything for the Irish. They whined about your being an 'absentee landlord', but if you did show yourself, at least anywhere near Tippcrary, they were quite likely to hide behind bushes and shoot you in the back, while you were walking about the estate. They resisted every enlightened attempt to clear their cabins and potato plots away and to give them regular employment in the cultivation of decent-sized fields, and in mixed farming on properly-managed estates. They seemed to think that it

24

THE POTATO MURRAIN

would mean the los^of their independence, that their wages, though regular, would be reduced in value through dirty wangles by the dealers in food, and that they would be worse off than before. They had a fixed idea that the only object of the landowners and the 'authorities' was to bleed and cheat them in every possible way, and they held on to their lazy beds' and their potatoes, as though their lives depended upon it. That made it easy for the agents to squeeze a little more out of the property, which was sometimes a convenience, but it was sad that the Irish should resist every attempt to better their condition.

The natural improvidence of the Irish was, of course, the real cause of their misery. They never put any money by to meet their obligations. If the pig happened to die they couldn't pay the rent. And so they got into the hands of the Gombeen men. Usury was prohibited in Ireland, but with the Gom- been men it was different. There was nothing illegal about buying meal on credit and then immediately selling it back again, at a much reduced price co get a little ready money for the rent. The chain of transactions was something like this: the farmer, in return for an I.O.U. for £i became the legal owner of a bag of meal worth 135. Without moving the bag of meal, he then sold it back to the Gombeen man for ios., and had that much ready cash. In three months' time the Gombeen man sued the farmer for the ^i, but retired satisfied with 55. or 6s. interest and another I.O.U. for .£1, with which, in due course, the process was repeated. The plight of the farmer in the clutches of Gombeen men was miserable in the extreme, but the main thing was that by allowing the farmers to have resort to such help in times of trouble, the landowners did get their rent. The Irishman, for all his pride in driving a hard bargain with his neighbour, and his endless haggling over twopence, was a child in the understanding of money. When by some fluke a banknote came into his possession he would not infrequently pawn it to raise cash.

A 'parasite', by derivation, was 'one who supped at another's table'. In Ireland in 1845, the 'table' was the produce of the Irish soil, and the host was the population which raised that produce by its labour. The parasites were those who did nothing for their host but in their various ways supped on the rents, the votes, the rates, the profits, the usury, the taxes and the tithes. They constituted a complex and much ramified social organism growing within, and, in the case of absentee landlords, without, the body of Irish society. The juice, in its digested and fluid form, that this parasitic organism drew from the Irish population was money. In its undigested form it was the meat and the bread, the cattle, die pigs and the grain; while the share left for the

25

THE ADVANCE OF THE FUNGI

host was the potatoes, a few rags and a little cheap whisky. No doubt the parasitic organism would have taken the potatoes also, were it not that some- thing had to be left to keep the host alive. The various channels through which the parasitic social organism sucked the wealth of its host constituted collectively, its 'mycelium' or root-spawn. And it was quite apparent that if the impoverished Irish were now stricken by a natural calamity, the parasite would suffer also.

As news was received of the inexorable spreading of the Potato Murrain throughout the length and breadth of Ireland, and the cottiers, who had paid little attention to the blighted condition of the foliage, dug nervously in their plots and found the potatoes going rotten in the ground, the English authorities began also to take alarm. A commission of inquiry was appointed by Sir Robert Peel, and Doctors Lindley and Playfair went to Ireland where they were joined by Robert Kane. Kane had written a book on the industrial resources of Ireland, and Lyon Playfair, a minor chemist, was a great sitter- upon-commissions — he subsequently insinuated himself into the household of the Prince Consort, became a Baron and endeared himself for ever to connoisseurs of fatuity by announcing, when exhibiting the synthesis of water to Queen Victoria, that oxygen and hydrogen would have the honour of combining in her royal presence !

The commissioners certainly sent back news of the true extent of the disaster, but in reporting on the cause of it they played for time, with many pious references to the will of the Almighty. The pressing need, they said, was for them to examine the possible means of saving those potatoes that were not yet diseased. They should be spread out on the soil to harden and dry, for three days after lifting, if the weather was fine (in November) ; they should not be stored in pits, as was usual, but carefully laid out in dry peat ashes, two inches apart, and built up in layers of the ashes into a clamp which was to be neatly thatched, according to a diagram. Alternatively, hurdles might be placed over the tops of lime kilns, and the potatoes spread on bracken over the hurdles to dry. As for the potatoes that were partially diseased, probably the best that could be done with them was to smash them up with brickbats and wash out the potato flour. But John Lindley had to warn the public that potato starch was no substitute for the potato as food. Nor was he alone in speaking of 'what is not bread and satisfieth not'. Animals fed only on starch died df starvation nearly as soon as when totally deprived of food.

The learned commissioners came back home after a few weeks, and for the time being the Irish were left to their fate. The commission had done little

26

THE POTATO MURRAIN

more than to advise well-known methods for storing potatoes, which were, in the main too finnicky and laborious for the Irish peasant, accustomed to storing his lumpers in pits. Now, with the rot and the curse on them, they were left where they were in the ground. Which, except for the danger of damage from frost, was perhaps as good a measure as any, for the disease developed rapidly among the potatoes in the pits. Mr. Foster had been present in October, at the opening of a pit in which some sixty barrels of potatoes — five months' provision for a family — had been put down a few weeks before. On sorting the good from the bad less than a single barrel were foiii: H to be sound. It was this rotting of the tubers that baffled understanding; there was a 'Blight', a mysterious something unknown and indefinable, affecting the potatoes wherever they might be, and the popular belief was that no one could tell whether this Blight came from the heavens above, or the earth beneath, or the waters under the earth.

All kinds of proposals were put forward in November and December of 1845, for stopping the rot in the potatoes. Farmers, botanists, chemists, mere writers-of-letters-to-newspapers, all had ideas. The potatoes were to be dried in lime, or spread with salt; they were to be cut up in slices and desiccated in ovens; and cottagers were even to provide themselves with oil of vitriol, manganese dioxide and salt, and treat their potatoes with chlorine gas, which could be obtained by mixing these materials together. It was mentioned casually that the chlorine should not be inhaled, and once again it fell to John Lindley to warn the public — this time of the very real dangers in generating poison gas in the home. There was, moreover, no reliable evidence that chlorine gas would have any preservative effect.

Dr. Morren, of Brussels, who believed with Mr. Berkeley that a mould fungus 'having seeds finer than the dust motes in the atmosphere' was spreading amongst the potatoes and causing the rot, suggested that the seed tubers for the coming season should be steeped in a mixture which in fact contained an oxy chloride of copper.1 The incomparable Dr. Lyon Playfair, also mindful that seed potatoes would be scarce in 1846, respectfully suggested that the English gentlefolk should make a practice of having the eyes cut away from all potatoes used in their kitchens, and placed on one side, as they would do for sets which could be distributed judiciously, and at little cost, amongst the deserving poor.

His Grace the Duke of Northumberland, through the Royal Agricultural Society of England, of which he was Vice-President, offered a prize of fifty sovereigns, or plate to that value, for the best essay on a remedy for the

1 54 Ib. lime, J Ib. copper sulphate and 7 Ib. common salt in 25 gallons of water.

27

THE ADVANCE OF THE FUNGI

Potato Disease, and two prizes amounting together to another fifty sovereigns for other essays on the subject. The prize-winning essays, published in the Society's Journal during 1846, contained useful accounts of the symptoms of the disease and of the course it had taken in various localities, but when it came to a remedy the essayists' principal achievement was to call the disease by a new and rather grand name: Gangroena.vegetabilis, or, simply Vegetable gangrene*. There was much scoffing at the Rev. M, J. Berkeley's fungal hypothesis. It was said that he had taken little notice of the general health of the plant, whereas his fungus was magnified seven-hundred-and-eighty diameters. The prize-winning effort on the cause of the disease amounted to a statement that it was due to the unhealthiness of the plants.

Meanwhile, the systematic botanists of Europe, whose occupation it was to collect and study, classify and name, all the species of plants, including the fungi, which were to be found on earth, were seizing upon one salient fact. A small mould fungus was always to be found growing on the diseased parts of the potato plants. Some workers found a rich variety of different sorts of moulds, especially when their technique for incubating them was none too careful, but there was one species in particular that was clearly to be associated with the Potato Disease. It was the species of Botrytis described by Dr. Montagne, the botanists were soon in tolerably close agreement about that. Most of them supposed that the Botrytis was responsible only for a secondary stage of decay, but whether it was the consequence or the cause of disease the little fungus was certainly of very great interest. It was an addition to the known flora of Europe, and a part of the Creation that had not been catalogued before. That it might be instrumental in causing a most deplorable loss of human life, through famine, in Ireland and elsewhere, was a circumstance that gave added zest to its investigation, for even cryptogamic botanists were human; but the part that this microscopic and colourless plant was playing in human affairs was nominally outside the scope of 'pure' botanical science. The botanists were interested in the fungus for its own sake.

The first botanical worker to discover a plant previously unknown, whether it was as small as a mould or as large as a Sequoia tree, not only had all the thrills and satisfactions of discovery ; he came in for a good deal of most gratifying renown among his fellow workers. Providing that he described his find adequately and accurately according to the botanical canons — in short, according to the rules — and published his description, he had the very great privilege of assigning a name to that which he had found. He was no less than Adam, in regard to his find, for whatsoever he called it, it was.

28

THE POTATO MURRAIN

There were several rivals for this honour, over the fungus which grew on the blighted potato plants, and the names invented for it were sufficiently expressive of its destructiveness. Mile. Libert, in Belgium, would have had it called Botrytis vastatrix Lib.; Desmazteres, in France, Botrytis fallax Des.; but Dr. Montagne, who load described the fungus adequately at a session of the Societe Philomathique in Paris on August 30th, 1845, was considered to have the priority by a few days, and despite a certain amount of disappointed snarling in some quarters, it was agreed that the fungus should be called Botrytis infestans Mont.

Dr. Montagne sent his sketches and des- criptions of Botrytis infestans to his friend the Rev. M. J. Berkeley in England, and they were formally published with Berkeley's 'Observations, Botanical and Physiological, on the Potato Murrain', in the first number of the Journal of the Horticultural Society, in January 1846. To make sure that the precise description of the fungus should be equally intelligible — or unintelligible — to scientific workers of all countries, and in all subse- quent ages, it was written, as was customary for such new entries in the inventory of Nature, in Latin. Thus to the Vulgate, and in the vulgus, of Science, was appended the following inscription:

BOTRYTIS INFESTANS. MonL, coespitibus laxis erectis albis apice plus minus ramosis, rams passim nodosis erecto-patentibus, sporis lateralibus terminalibusque solitarius ovoideo-elliptitis pro ratione magnis concoloribus subapiculatis, nucleo granuloso . . .

And so on. The aerial parts of the fungus, when magnified sufficiently for details to be revealed, appeared somewhat as shown in Fig. i. The growth of mould, visible to the naked eye as a white fringe of down, round the decayed areas and on the underside of blighted potato leaves, was made up of multi- tudes of exceedingly fine, semi-transparent, branching filaments, bearing colourless lemon-shaped spores. These spores broke away when mature and drifted in the air. They had all the appearance of fruits or seeds borne on the branches of the microscopic plant. Berkeley did not observe these spores in

29

FIG. i. A small part of the under surface of a potato leaf, magnified to about 100 times its natural size, showing the Potato Blight fungus, Botrytis infestans Mont., growing out of the stomata. Berkeley, 1846

THE ADVANCE OF THE FUNGI

process of germination. Dr. Montagne was not at all sure, but it did seem to him that for all that these spores were so very minute, they were in reality spore-cases or 'sporangia* which, when ripe, contained smaller granular bodies which might be the true spores or 'seeds' of the fungus.

In another sketch, Fig. 2, Berkeley showed the 'root-strands' — constituting the mycelium or spawn of the fungus — as they were to be seen under the microscope in the interior of a potato leaf. The leaf-thickness was made up of several layers of cells: on the top there were the cells of the upper epi- dermis (which Berkeley did not trouble to show); beneath them came a tier

FIG. 2. Section of a potato leaf, greatly magnified showing the spawn- strands of the Potato Blight fungus creeping amongst the loose tissue of the underside, and sending out fertile shoots through the stomata. The mould is still young, one shoot not having yet formed any branches or fruit.

Berkeley, 1846

of vertical or 'palisade' cells, closely compacted, to which the leaf owed much of its rigidity and mechanical strength; while, under the palisade cells in their turn, the interior of the leaf was a kind of absorptive sponge, made up of thin- walled cells jumbled about, with air-spaces between them. The intercellular spaces communicated with the air outside the leaf by way of a multitude of minute pores — stomata from the Greek for 'mouths' — by which the lower epidermal cell-layer was perforated. The spore-threads of the fungus wound about in the air-spaces between the cells and took advantage of the stomata, as openings through which to put out their spore-bearing hyphae. Normally, when no growth of the fungus was present, the moist and

30

THE POTATO MURRAIN

spongy tissue of the potato leaf manufactured food for the plant, and it had also a certain partial resemblance to a lung. It was bathed in air; with the help of sunlight it absorbed the gases which the plant needed from this air; and it gave off water vapour and other gaseous waste products of its living processes. It was evident that the spawn of the fungus, invading this tissue, would cause profound physiological disturbances. If a man could imagine his own plight, with growths of some weird and colourless seaweed issuing from his mouth and nostrils, from roots which were destroying and choking both his digestive system and his lungs, he would have a very crude and fabulous, but perhaps instructive idea of the condition of a potato plant when its leaves were mouldy with Botrytis infestans Mont.

The Rev. M. J. Berkeley certainly did not indulge in any such fancy, but in his observations on the Potato Murrain he made it quite clear that the spawn of the Botrytis grew within the tissue of the potato leaves and that it put out its spore-bearing branches through the stomata. That in sonic way the fungus drew its substance from the contents of the leaf-cells and thereby contributed to their decay was not in dispute. That the fungus might spread from plant to plant in the field by means of its air-borne spores was probable enough, and though it was difficult to see how a fungus growing on the leaves could affect the tubers underground, and even after they had been lifted and put into store, it was conceivable that the organism had some way of pro- gressing through the underground stems of the plants so that the spawn of it was present in the tubers during growth. The point at issue was whether or not the fungus could attack healthy potato foliage. By January 1846 the prevailing belief was still that the fungus could establish itself only on foliage that was already languid or moribund through Disease. And if this were so, the detailed study of the fungus could not help much in solving the riddle of the Potato Murrain. It would still be necessary to find the cause of the Disease.

The mysterious principle, so glibly spoken of as 'Disease', was highly illusive. Most people seemed to regard it as an Absolute, linked without material agency to the Will of God. Even the natural philosophers, for the most part — the very botanists and chemists — were vying with one another in postulating intangible causes for invisible Disease preceding the fungal attack. Electricity was much discussed. Somebody had seen a lambent phosphorescent light playing over potato fields at night, somewhere in Ireland, where the disease was very bad. This phenomenon was about equally suggestive of a silent discharge of electricity or a personal appearance of the Evil One. Then again it was a well-known fact that some varieties of

31

THE ADVANCE OF THE FUNGI

potatoes degenerated in cultivation, seeming to pine away and lose their productiveness when grown for some years running in particular localities. 'Degeneration' might be the cause of Disease. Others confidently proclaimed that the Disease was caused 'by simple eremacousis or excolation in conse- quence of a deficiency of vital energy in the plant*. 'Simple' eremacousis being a supposed burning or internal combustion of the weakened plant owing to the oxygen in the air having become too strong for it. It was note- worthy that in this controversy it was the Rev. M. J. Berkeley, a man accustomed by the exercise of his clerical profession to a certain amount of Christian protestation, who rejected all the nebulous, transcendental and spiritual explanations, while it was the more materialistically-minded scientists who most eagerly espoused them.

Berkeley was at one with Michael Faraday in his distaste for the postula- tion of unknown causes for natural phenomena, and in asserting straight out that the 'Disease' was non-existent, and that the growth ofBotrytis infestans as a parasite on the potato plants was sufficient to explain all the phenomena of the Potato Murrain, his philosophy was that of his great namesake, author of the Principles of Human Knowledge. He rejected an unknown and unknow- able nuotnen: the 'Disease', and directed his attention to an observable phenomenon: the growth of a parasitic fungus on the plants. In his famous Observations of January 1846, Berkeley was able to sweep away a number, but not all, of the objections to his fungal hypothesis. For a start he was able to produce evidence that the Potato Murrain, and the particular species of fungus associated with it, had not appeared on earth for the first time during the previous year. A Dr. Bellingham had described an outbreak of precisely the same kind affecting potatoes in Canada in 1844, and one Joachim Acosta had transmitted information to the French Academy which then seemed to indicate that the malady had long been known in Bogota, where the Indians lived chiefly on potatoes. The creation of Botrytis infestans Mont, was probably coeval with that of the potato itself. Then, he was able to point to a number of other moulds which so far as he knew attacked only living and apparently healthy plants. However much you tried you could not get these moulds to grow on foliage that was dead or decaying. The Potato Blight fungus was not a 'saprophyte', it was not a plant that lived on the dead; it was a true parasite or vampire that supped on the juices of the living potato plants and thereby blighted and destroyed them.

No! said Dr. Lindley, the other members of the Government commission, and most of the botanists in Europe. The tissues of the plants were charged with water they could not eliminate, some degree of putrefaction or incipient

32

THE POTATO MURRAIN

decay set in, and then came the mildew. Or the long-observed tendency of potato varieties to degenerate in some way became universal and acute in an abnormal growing season, and so pre-disposed the plants to fungal attack. Or the unstable nitrogenous constituents of potato tubers and foliage were disturbed by electricity or corrupted by the wet. Something went wrong. They could not believe that the Botrytis could have established itself unless the plants were already debilitated and lacking in some power of resistance to agencies of decay.

33

CHAPTER II

FAMINE IN IRELAND

WHILE botanists wrangled and compared notes about their pretty fungi, it was winter in Ireland. As the small supplies of sound or only partially- blighted potatoes rapidly diminished some four-and-a-half million cottiers and poor farmers faced starvation. One or two of the landowners, who had managed to retain personal control of their estates, and were not themselves impecunious and on the verge of bankruptcy, forgave their tenants the payment of rent for a year, which meant that they could keep their corn for themselves and use it for food. Already, in October 1845, there were hills in Donegal ablaze with bonfires at night, marking local jubilation at such generosity on the part of Lord Kildare. But these humane concessions were very rare; the majority of the landowners, through their agents and col- lectors, pressed harder than ever for the rents, to make sure of them, while the getting was still good. The export of corn, and even of potatoes from some districts in Ireland was not stopped. There was food in the country, perhaps enough of pigs and cattle and grain to have nourished the whole population until the next harvest, but the people had no money wherewith to buy back what was taken from them in rent.

In England, the reports of the commission of inquiry had made it plain to Sir Robert Peel that the provision of some measure of relief during the approaching famine would be unavoidable. Peel, insolent and aloof in manner, an aristocrat of the rising industrial breed, whose wealth came from the Lancashire cotton mills, was not greatly concerned to alleviate human suffering. He exploited the situation with magnificent political opportunism. His pledge to his Tory supporters to pursue a vigorous policy of Protection had served its purpose and brought him into office and power. Now he was scheming to turn apostate and to use that power, in defiance of his party, for the advancement of the directly opposite policy of Free Trade. The Corn Laws, enacted in 1815 to prevent the price of wheat from slumping too far below the famine prices which had obtained during the Napoleonic wars, operated to the great advantage of the landowners, the old traditional aristocracy who drew their revenues from the farms. The Laws imposed heavy duties on imported grain and so 'protected' home agriculture. The Tory party was chiefly representative of the wealthy landowners, and Peel had made himself their darling. But there was one part of the Whig case for

34

FAMINE IN IRELAND

Free Trade that was greatly to his mind. The Anti-Corn Law League, Cobden, Bright, and the rest, had been making out that Free Trade would bring the people the blessing of cheap bread. That was as might be. Those who had no bread could eat cake for all Peel cared; he was not a sentimentalist. But Free Trade would operate to the advantage of a caste then rising to effective power, towards which Peel belonged by birth and naturally gravitated. The English industrialists had a virtual monopoly of the world's machine manufactures. By the timely exploitation of this monopoly, with all the ports of the world open to them, and laissez-faire to trade as they pleased, the mill-owners and the iron-masters and the ship-builders, the brokers and the bankers would build for themselves an Empire the like of which had never been seen before. Theirs would be the Empire, the power and the glory. Theirs would be the name of England, and of that new might and richness he, Robert Peel, would be an architect; no more would he toady to the declining, land-owning oligarchy that in his heart he despised. The news of famine in Ireland was a godsend. Oh, what most excellent use could he not make of that!

On January 2yth, 1846, Peel made his great speech in the House of Commons for the repeal of the Corn Laws. His heart bled for the suffering Irish; in England there was no grain to send them, for in England also the shortage of food was causing the gravest distress; the only thing that could be done, in the name of God and humanity, was to suspend the Corn Laws and admit foreign grain into the country. The Tories were aghast. For months the tremendous angered debates went on. Neither friends nor enemies were taken in, for Peel's humanitarianism reeked of guile. The Irish had been left to starve before, their present misery was being exaggerated, could not such epoch-making and dangerous measures be deferred until the real extent of the distress was seen? In histrionics Peel surpassed even himself. 'Good God', he cried, 'are you to sit in Cabinet and consider and calculate how much diarrhoea and bloody flux and dysentery a people can bear before it becomes necessary for you to provide them with food?'

While the debates continued Peel set up a relief commission, and a number of shiploads of maize were imported from America. The first issue of maize meal, from relief centres in Ireland, was made early in March. Maize was chosen, first because it was cheap and there was a large surplus available in America, and secondly because it was practically unknown in Ireland, and it could be distributed by the Government, at a low price, Without too much opposition from the Irish dealers in grain. It was all important that the relief measures should not dislocate trade. And how could the corn merchants

35

THE ADVANCE OF THE FUNGI

have sold their wheaten grain or flour, at prices which took proper advantage of the distress, with the Government in unfdr competition with them? The choice of maize solved this difficulty, for no one in Ireland would buy maize meal if he could possibly afford to buy wheaten flour.

The maize meal was quite wholesome, and some of the gentry in Ireland themselves ate bread made with a proportion of it, to set an example, and to popularize the unfamiliar stuff amongst those it was destined to sustain. For all this, the ever-ungrateful Irish grumbled at the coarse yellow maize meal and called it 'Peel's Brimstone'. It was not easy for stomachs accustomed to distention by a bulky diet of potatoes to accommodate themselves at once to meagre rations of maize; but any inconveniences on this score were trifling when so many were dying of exhaustion by hunger, and the fever that followed in its train. In a short time the marvellously flexible digestive system of man accommodated itself to the maize, which for eighteen terrible months did sustain many hundreds of thousands who would then otherwise have joined the dead.

If the plight of the Irish was wretched in the spring of 1846, what had they to anticipate in 1847, if God ignored their prayers and sent just such another season as the last? If the Blight once again destroyed the potato crop? Already many of the fields were bare, for seed potatoes had been consumed, and there were many prophets of woe who said that the potatoes were lost for ever to Ireland, that they were not to be trusted again. Where was the use of plant- ing them, of bending one's back to the spade? Many of the lazy-beds were empty, tillage was neglected.

Those who had hidden away and saved enough seed potatoes to plant their land had cause, as spring progressed into summer, to congratulate themselves on their faith in God's mercy. The plants were healthy! The murrain had passed over!

It was not a good summer, all over Europe the grain crops now were suffering, but the potatoes were spared. Or so it seemed, until about the end of July. Then the Blight appeared on the potatoes once again.

'On July 2yth', wrote Father Matthew, '1 passed from Cork to Dublin, and this doomed plant bloomed in all the luxuriance of an abundant harvest. Returning on August 3rd I beheld with sorrow one wide waste of putrefying vegetation. In many places the wretched people were seated on the fences of their decaying gardens, wringing their hands and wailing bitterly at the destruction which had left them foodless.'

Funds were raised, much help came from America, the Society of Friends, as usual, were the first on the scene of disaster and the last to leave, but there

36

FAMINE IN IRELAND

were difficulties in the way of the main organization of relief. It was not so much the cost of the maize, for that would not greatly strain the resources of a nation that had recently effected great economies on the relief of pauperism at home, introduced the Income Tax, and returned a budget surplus of over five millions. The trouble was that the maize could not be given away: the demoralization of receiving rations of chickens' food without having to work for them would be worse for the Irish than being left to die. There was no precedent for such organized relief as that which now became necessary, no English Government had ever undertaken anything like it before, and there was great concern over the moral issues. The principle of Poor Law relief in England was that of 'offering the workhouse', and clearly there were no workhouses to offer half the population of Ireland. An expensive organiza- tion of relief works had to be set up which would make the whole of Ireland for the time being one vast emergency open-air workhouse. The only task that could be set everywhere was that of road-making; and it was extremely difficult to make the task-work on the roads less attractive than any form of employment normally available, in so miserable a part of the Kingdom as Ireland. The Committees did their best, but, even so, the people flocked to the roads and would not cultivate the land, and to the despair of the charitable there were some malingerers, who preferred the pretence of road-making to their habitual employment on farms and estates at sixpence or so a day. It was a shocking thing that some should try to get relief when they were not really starving, and in February 1847, a 'means test' was imposed. It was simple, and it effected a considerable economy. It was called 'the cooked food test'. Large iron boilers were installed at the relief centres, and the maize meal, sometimes mixed with a little rice or oatmeal, was boiled in water to make stir-about. In this way the one-pound portions of meal were made to swell into two or three pounds by absorption of water, and they were dis- tributed thus — as a wet mash. The mash could not be stored, or it would ferment; it had no value on the market, it could not be sold or pawned; and as it was most unpa1 "able the Government could feel content that nobody would work on the roads for it who was not in a reasonably necessitous plight. The average cost of each ration was twopence, including the cost of the staff of the relief committees and all incidentals. As a further precaution many of the boilers were set up a mile or more away from the villages they served, so that those who were very sick or enfeebled would either die on the way or share the portions of those who could make a personal attendance to get them. One of the beauties of the cooked-food test was the pleasure it gave the righteous and the prosperous to reflect that the Government was not only

37

THE ADVANCE OF THE FUNGI

providing food for the hungry, but even cooking it for them. Though indeed the only thing of which there was little shortage in Ireland was turf from the bog.

The local authorities and magistrates, representative of the landowners, shelved their responsibilities, and the burden of organizing the relief works throughout the country fell almost wholly upon the civil servants, the officers of the Board of Works in Dublin. Theirs was a story of devotion and often of heroism. They worked day and night to make the best of mean schemes; not a few of their number were assaulted or murdered by those who objected to the task system, many others died of the famine fever, which all had to brave. The sight of the haggard, half-naked, sick and emaciated people who dragged their aching bones for miles to perform their day's task on the roads was too much for some of the engineers who had to supervise such labour. Sometimes, when the weather was very bad, they held it sufficient if the folk made their appearance in the morning, and came back only if the weather improved later in the day. There was one who said that as an Engineer he was ashamed of allotting so little task work for a day's wages, while, as a man, he was ashamed of exacting so much.

A number of the landowners sought to divert funds and to get free 'relief labour' for the work of draining their particular estates; and speculators in Irish railway stock clamoured for the diversion of the labour to the piling up of railway embankments. But the Government, the landowners and the rail- way company promoters could not agree terms, and the construction of roads went on, many of them from nowhere to nowhere. In March 1847, 734,000 men, corresponding with their families to some three million people, were engaged on the relief works.

The Government did not assist emigration, contending that the proper criterion of fitness to emigrate was the possession by the applicant of the initiative, the means and the courage to do so. Any interference with this natural law would only flood the colonies with unwanted and undesirable people. There was mass emigration nevertheless, passage money was sent by relatives who had already escaped to the New World, and all over Ireland the lamentations of departure mingled with the keenings for the dead. In 1847, ninety thousand set out for Canada alone; and of this ninety thousand, two thousand died of fever before they reached Dublin or Kingstown, while thirteen thousand more died in Liverpool or during the passage, or at quaran- tine stations on the other side. Those who survived spread a trail of typhoid about them as they penetrated into the Canadian interior. Fever everywhere accompanied and followed the famine.

38

FAMINE IN IRELAND

In 1847 the sadly reduced acreage under potatoes in Ireland escaped the Potato Blight — or, it should rather be said, the Blight attacks were local and relatively unimportant. There was good weather, brilliant sunshine, that year, from July to September. And over the whole of Europe the harvest, both of grain and potatoes, was abundant. The two worst years of famine were past. The relief works and the relief centres were gradually closed down as the new crop of potatoes became available, and the survivors were left to convalesce, as best they could, from the scourge that had fallen upon them. There was no decrease in the rents, and after the famine came all the horrors of the evictions. With the rent unpaid families were cast out of their homes, with their bundles and bits and sticks of furniture about them, to beseech shelter of heaven or crowd the few pestilent workhouses. The official relief measures, for a whole population, over a period of eighteen months, had cost Great Britain the unheard-of sum of ^7,673,701. Nearly eight million pounds! Of course, a substantial part of this was to be repaid out of the Irish rates. It never was repaid in that form, but the debt was offset by the extension of the Income Tax to Ireland in 1853, so that the landowners there had to make some contribution after all. The poverty in Ireland, especially in the Congested Districts of the West, remained as a permanent sore. The Potato Blight was in Ireland for ever; it would become epidemic and ravage the crop again, whenever weather conditions favoured its development. In the years from 1845 to 1860 a million people died in Ireland alone as a direct consequence of the famine, and one and a half million emigrated. The part of the Potato Murrain in contributing to the sufferings during the 'Hungry Forties', in England and other parts of Europe, was a matter for the grimmest conjecture.

The Potato Blight fungus, Botrytis infestans Mont., had revealed itself as a new and formidable enemy of mankind. By destroying the stable food supply of a human society already very sick from economic causes, it brought about more of death and suffering than any other disaster since the Napoleonic Wars. It was an historic determinant of human affairs, for in 1846 it was the straw that turned the wavering inclination of British high political policy away from self-sufficiency and the protection of home agriculture to Free Trade and the unbounded expansion of commerce. The passage, on June 26th, 1846, of the Act which ultimately repealed the Corn Laws was perhaps the most significant single event in the history of the British Empire. The Duke of Wellington's comment was: 'Rotten potatoes have done it all; they put Peel in his damned fright'. That little fungus, only to be fairly seen in the strangely lighted field of the microscope, with its filamentous spawn and

39

THE ADVANCE OF THE FUNGI

its translucent spores, not only brought famine to Ireland and unlocked the doors of England's Golden Age; it shed new light on the nature of Disease, awakened the natural philosophers to the significance of those living things that God created small, and called into being a new branch of applied science, second only in importance to medicine and human pathology — the science which was to have for its province the defence of the health of the crops. Very slowly that science took shape, and won its way out of Laocoon-like struggles with doubt and indifference, superstition and obscurity, after Botrytis infestans Mont, had written its name across the potato fields of Europe. Nearly a hundred years were destined to pass before the erasure of that signature would seem to be in sight, and historians could attempt to tell a half of the story.

It was said, in 1847, that all human power, experience and learning had proved vain and futile to discover any antidote to the Potato Blight when weather conditions favoured its spread. This was not quite true, for although even the fungal nature of the Blight was still very much in dispute, there were fragments of certain knowledge about its course, which pointed to some ways of mitigating the damage. It was observed and generally admitted that the Blight began on the foliage of the plants and later made its way to the tubers. There was o&e drastic measure that the potato growers could some- times employ with advantage. They could amputate; they could cut down the potato haulms before the disease had reached the tubers. When this was done the potatoes might not be fully grown, but most of them would be sound. This measure was advocated by Dr. Morren in Belgium within a fortnight of the first outbreak of the Blight in 1845, and had it at once been adopted in Ireland, it would undoubtedly have saved much of the crop in the famine years.

Then it was noticed that the potatoes which grew nearer the surface of the ground were more often blighted than those which were more deeply- covered. It was thought that the upper tubers might be more tender or immature, and therefore more susceptible, but a good cover of earth over the potatoes might have a protective effect. An interesting fact, reported in The Cambrian newspaper, was that potatoes grown in the immediate vicinity of the copper smelting works at Swansea remained healthy and green, while those in Sketty, Llangyfelach, and the surrounding districts were universally diseased. It was difficult to see what the cause of this might be. John Lindley said it might be urged by the advocates of atmospheric contagion that one miasma had the power of repelling another from the potato fields. One correspondent wrote to The Gardeners9 Chronicle and said: supposing the

40

FAMINE IN IRELAND

Potato Murrain really was caused by a minute fungus, why had that fungus waited for over two hundred years after the introduction of the potato into Europe before manifesting itself? Was it possible that the fungus had recently migrated to Europe from South America, where the potato grew wild? He had looked up the weather records for 1845 and found that westerly winds had prevailed during all August and into September. Could the spores of the fungus have been blown over from the American continent owing to some singular changes in the winds? But if the living spores had been carried over some three thousand miles of ocean by wind it must have been years before 1845. Df- Morren provided an account of the disease on potatoes in the vicinity of Lille in 1844, and said that it had first been observed at Liege in 1842.

John Lindley was less insistent on his theory, by 1848, that the plants were water-logged, and he had made some practical experiments arising out of the idea that the Potato Blight might be due to the degeneration of the potato through over-domestication. There was nothing nebulous or chimerical about this thought. Several kinds of wild potatoes had been sent to the Horticultural Society of London, at one time or another, from Chili, Mexico and Peru. These differed greatly from the domesticated potato, and it was very possible that some power of resistance to disease enjoyed by the potato in its wild state had been lost in centuries of domestication. Even if the Rev. M. J. Berkeley was right in thinking that the Blight Fungus could attack healthy plants, it still took two things to account for the devastation: the aggressiveness of the fungus and the weakness of the potatoes. If the Blight was an instance of the parasitism of one species of plant by another then a better understanding of the Blight was to be sought in two ways (a) through the study of the parasite and (b) through that of its host. With all due respect to Mr. Berkeley, John Lindley was of the opinion that the latter approach was just as important as the former. 'Amongst the many specula- tions that have been entertained concerning the Potato Disease', wrote Lindley in 1848, 'one consisted in the belief that in order to be secure against its future ravages it was only necessary to bring the plant once more from its native country and to begin over again the process of domesticating it/

To test this possibility it was necessary to determine whether or not the wild potatoes were susceptible to the Blight when grown in Britain. In 1846 and '47, Lindley collected as many sorts of Central or South American potatoes as he could obtain, and had them grown in the Horticultural Society's gardens at Chiswick for purposes of observation. There were New Granada potatoes and Golden Potatoes from Peru; but amongst all the different sorts

THE ADVANCE OF THE FUNGI

perhaps the most interesting were those of which tubers had been received on July 25th, 1846, from a German gentleman, one Herr Uhde, who was then residing or exploring in Mexico. The packet was marked only: 'Native Mexican potatoes from an elevation of 8000 feet/ The tubers of these wild potatoes were very small, it would have been hard to make a meal off them, even if they were good to eat. Some of them gave rise to very tall and weedy plants, which were thought to be the same as the Solatium Maglia, described by Molina and others, and found growing wild in Chile, in the latitude of Valparaiso. They also belonged, perhaps, to the same species which Darwin had seen on the Chonos Archipelago off the coast of Patagonia, during his voyage on the Beagle. Other tubers, from Herr Uhde's packet, produced plants of a particularly dwarf sort, bearing flowers very close to the ground and having 'potato-apples' or berries, which were about as large as black currants. The plants sometimes put out branches and blossomed again, at a maximum height of twelve to fifteen inches. The flowers were nearly an inch across and bright violet. Very few tubers were formed, many of the stems had none, and where they did occur they were small, flattened, some- what kidney-shaped, and of white colour, with white, crisp, semi-transparent flesh. It seemed that this member of the Solanaceac — the potato, tomato, egg- plant and Deadly Nightshade family — had never been described before. John Lindley considered it a distinct species, and in his 'Notes on the Wild Potato', in 1848, he recorded its characteristics in Latin and gave it the name of Solatium demissum. 'Demissum\ because it was a dwarf.

Very interesting, this dwarf wild potato, which grew in Mexico, worth noting certainly — but what good was it? Its tubers were few and diminutive, and it was just as severely attacked by the Blight as the other potatoes in the gardens. A promising idea seemed to have come to nothing. But had he not said all along that owing to abnormally wet seasons the potato plants became surcharged with water and then wet putrefaction set in? It did not matter whether the potatoes were wild or domesticated, they rotted just the same.

It was the wet, the everlasting wet. Andrew Murray, in The Book of the Royal Horticultural Society, later recorded some happenings during those years of the Potato Famine, which must have impressed the wetness of the summers, indelibly upon Dr. John Lindley 's imagination. He was the Secretary of the Horticultural Society, and in this capacity he had other things to do besides arranging scientific experiments in the Chiswick gardens. Those gardens were in the main a pleasure resort for the fashionable, and the wet 'caused inconvenience to great assemblages of people drawn together for enjoyment

42

FAMINE IN IRELAND

in the open air*.1 At one of the 'breakfast-fetes', which helped to make the gardens pay, tickets were sold, as usual, by exclusive lady-patronesses, at two guineas per head. In the marquees, 'gorgeous plate, fine china and sparkling crystal combined with the most delicate viands and high-priced wines to charm the eye and tempt the palate'. Then it rained — no less in Chiswick than it did in Ireland. Carriage after carriage deposited its fair and gaily dressed freight at the gates, and the cavalry lent their cloaks to the ladies — at two shillings and sixpence a time — to protect them during their passage from the carriages to the tents. The military bands played bravely to keep every- one in good cheer, the supply of champagne was liberal, the cold and the wet were almost forgotten. Then Dr. Lindley observed that the pillars supporting the tents were slowly but surely giving way in the wet. Disaster was imminent. He sent out into the streets, the pot-houses, the barns and smithies of Chiswick to hire men at any price to hold up the tents while the unsuspecting guests revelled within. The situation was saved. The fete even terminated with dancing on the wet and splashy grass, and it was said that a whole bushel of wet shoes and stockings were picked up in the gardens and neighbourhood next day, which had been thrown out of carriage windows as the owners drove off. Indeed it did rain, during the Hungry Forties.

1 For illustration see Cruikshank's Comic Almanac, 1846.

43

CHAPTER III

OIDIUM ON THE VINES

ON November 27th, 1847, the Rev. M. J. Berkeley had occasion to comment on the wisdom of encouraging a higher order of education amongst gardeners. It so happened that in Margate there was a clergyman so deeply imbued with a love of natural history and science that he had set up a literary and scientific institute to encourage the talent for inquiry which he found existent in no small degree amongst his parishioners. Already, one of these persons, of station so humble that it was almost unmentionable without apology in polite society, to wit *a mere dispenser of the produce of the milky mothers of the herd* — or milkman, had written an essay on the lack of sanitation in Margate, which had startled the whole scientific world. And now another most meritorious piece of work came from the pen of a parishioner who was a mere working gardener.

The grape vines near Margate had been attacked since 1845 by a peculiar malady, never observed before. Every vine, whether in the open borders or in the houses, was affected. The disease appeared on the young shoots, tendrils and leaves, like a dusting of white and pulverulent meal; it spread rapidly on to the grapes themselves, withering the bunches when they were small and green, or causing the grapes to crack and expose their seeds when they were attacked later. The disease was accompanied by an unpleasant mouldy smell, and it ended in the total decay of the fruit. But one Mr. Tucker, gardener to J. Slater, Esq., of Margate, had not stood by, wringing his hands and saying that it was the will of the Almighty that the murrain on the potatoes should now spread to the vines. On the contrary, and in the exercise of an initiative most exemplary in a labouring man, he had obtained access to a powerful microscope and examined the afflicted foliage. He saw that a powdery mildew was growing on it, and then, without waiting for the fungus to be identified, and untroubled by any philosophic doubts as to whether it was the cause or the consequence of the disease, he looked about him for a practical way of stopping it. For once, in the history of plant pathology, the announcement of the outbreak of a new disease was coincident with the publication of an effective remedy for it.

Mr. Tucker was accustomed to using sulphur as a specific against mildew on peach trees, and he now tried sulphur for this new trouble on the grape

44

OIDIUM ON THE VINES

vines. He made up a mixture of flowers of sulpHur and lime in cold water and applied it to the leaves with a sponge. The treatment worked admirably: the mildew was killed on the affected shoots, its spread was prevented, and the rest of the grapes and the foliage grew away unharmed. In the end there was a good crop in the houses under Mr. Tucker's care, wliile in some of the other vineries in the locality there was not a single sound bunch of grapes to be seen.

Mr. Tucker, signing himself 'Progressionist', published a humble account of his observations in a letter of September 22nd, 1847, t° the popular Gardeners9 Journal, and the Rev. M. J. Berkeley, in the more influential Gardeners9 Chronicle, pronounced that the causal fungus was a species of 'Oidium' not previously reported. He therefore translated 'Tucker* into Latin and named the parasite: Oidium Tuckeri. Mr. Tucker's name was destined not only for immortalization in the dusty records of cryptogamic botany, but for immediate, widespread and mournful celebrity.

The new disease of the grapes broke out in France. According to Dr. Montagne it was first observed, in 1848, on vines by the stoves at Versailles; whence it spread to the outdoor trellises and so to the neighbouring vine- yards. By 1851 it had swept over the whole of France, south into Portugal, and along the whole length of Italy from the coast of Liguria to Naples; then, in the late summer of that year, it seemed to take a northerly course, through the Tyrol, overrunning Switzerland, and penetrating into the vine- growing districts of south Germany. Everywhere it caused consternation and panic among the vine-growers; it threatened their industry with ruin. The dread Oidium ravaged the finest of the vines. The Frankenthal, the table grapes cultivated by the stoves, were its first nurse; then the Chasselas, the Muscats, the Malvoisie, the White Grapes, the Tressaux, all the Hun- garian strains, the Hermitage. ... It was most destructive of those grapes which had the finest and most delicate skin and the most succulent fruit. The varieties which offered resistance were those which were least esteemed: the grapes of North America, the Gourneys, the Cots of Touraine. ... By 1852 the choice vines of Madeira had been so ravaged that it seemed the cultivation of grapes would have to be abandoned on the island and orange trees planted instead.

There was less resistance this time to the theory that the fungus might be the cause of the disease, for it appeared first on those vines which the peasants called *gaillarde\ There were village mystics, and witch-like old women who said that the brave and joyous vines, which challenged the Gods with the greatest apparent vigour and health, would naturally be the first to suffer —

45

THE ADVANCE OF THE FUNGI

that they were in some occlilt way predisposed to disease. Some of the botan- ists also had theories about a 'plethora*, or mysterious and unhealthy repletion, as a possible cause of the observable growth of mildew. But practical men were not disposed to believe that a plant could be diseased for the very reason that it was in too excellent a state of health. No! said Dr. Montagne, and Bethola, and Bouchardet, and Cuppari, and Gaddi, and Keller, and Hugo von Mohl, and Payen, and Savi, and Tulasne, and the members of the Venice commission of inquiry. This time we have caught the rat with the flour on its nose; it is the mildew, the powdery growth of Oidium Tuckeri, that is exhausting and killing the leaves, starving and splitting the grapes! Now Berkeley had the majority of the European botanists on his side. If the mildew flourished and spread most rapidly on the finest vines, growing on the best soil, it was because those had the sweetest sap, and sweet sap was food for the mildew as well as for the grapes.

But in his eagerness to demonstrate that the Oidium Tuckeri grew as a parasite on the vine foliage, Berkeley made an error of observation that for a time seriously weakened his case. In his first published sketch of the fungus he showed it growing within the tissues of the leaves, and sending its spore- bearing threads out through the stomata as did the Blight fungus on the potatoes. How could the fungus be anything but a parasite when its spawn was within the leaf, tapping the substance of the living cells? Mr. Tucker made the same mistake. Influenced by Berkeley's picture of the Potato Blight fungus, and too readily assuming that that was how any parasitic fungus on a leaf would grow, he had contrived to see, through his powerful microscope, something he expected to see, but that was not in fact there. 'Mycelium' under the leaf-cuticle, among the cellular tissue, ramifying and crossing in every direction. There were many pitfalls in Nature for those too quick to see what they wanted to see.

It happened that one of those who did not accept the 'fungal hypothesis' was J-H. Leveille, doctor of medicine in Paris. And Leveille, for all that he had only a modest and unremunerative practice, never knew how to get on in the world, and never wore even the red ribbon of the Legion d'honneur, was one of the greatest cryptogamic botanists in France. He made mistakes of interpretation, but very rarely of observation, and in 1851 he published a methodical classification of the many species of fungi composing the genus to which the Oidium belonged, decades in advance of his time. When describing the Oidium before the Societe Philomathique in Paris and writing about it in the Revue Horticole, he pointed out that it was one of the com- monest kinds of fungal growth found on the foliage of plants, it closely

46

OIDIUM ON THE VINES

resembled the Powdery Mildews of the rose, peach, wheat, pea and hop, and its habit of growth was very different indeed from that of the Potato Blight fungus.

The spore-bearing 'stalks' of the Oidium did not arise from spawn within the leaf, but from a closely-interwoven web of glistening threads which crept over the leaf-surface. There were no spawn strands of the fungus to be found within the leaf at all. Straight stems arose from the superficial mycelium, bearing three, four or five oval, glass-like or 'hyaline' spores, joined end to end like beads of a necklace. These spores germinated when they had fallen on to a fresh part of the leaf-surface, putting out threads which were the beginning of a new tangle of mycelium. Leveille was no artist, but a beautiful drawing of such a fungus, as seen under the microscope, agreeing with Leveille's description, was provided a little later by Charles Tulasne.

Leveille made a-much of the point that the Oidium had, apparently, no 'roots' penetrating the leaf. Without roots it could not very well be a parasite. It was an entirely superficial growth, which could be wiped off the leaves between finger and thumb, so that at most it was a 'false parasite', like ivy on a tree. As for the source of its nourishment — was it not easily conceivable that there might be some moist exudation, from leaves sickly from some internal cause, on which the mould could feed? Moulds would grow on the merest film of moribund juice. The areas under the patches of mould were always paler than the surrounding parts of the leaf, and no one could say which came first — the mould or the pallor. Leveille's view was that the fungus did not propagate the malady, but that it was due to a 'primitive derangement of the tissues' to which the vines had always been subject, but which had become serious and destructive because of a succession of 'douce9 seasons. It was not easy to account for the universal presence of the fungus in association with the sickliness, and Leveille had to resort to the already half-discredited theory of spontaneous generation. The morbid changes in the leaf tissue, he said, brought the living fungus into existence.

Berkeley still had to defend his 'fungal hypothesis', and when commenting on Leveille's paper in 1851, he said:

'Where the mind can be brought to adopt notions of spontaneous or equivocal generation there is little difficulty in these matters, or at least the difficulty is thrown aside, but all patient investigation is against such notions, we must be content to treat the propagation of even such minute bodies as Oidium Tuckeri as we do those of the flowering plants. When a large crop of white clover makes its appearance on land recovered from the sea, it is

47

THE ADVANCE OF .THE FUNGI

an easy solution of the difficulty to say that the plants have been generated spontaneously from the soil. It may not be easy to account for their presence, but yet the lover of truth will not readily solve the difficulty by so unwarrant- able a conclusion. In the case of the Potato Disease and the Grape Mildew, it appears that the parasites were not previously known. The conclusion is, as Morren well remarked about the Potato Blight, that they must have been

FIG. 3. The Oidium or Powdery Mildew of the Rose. The appearance of the Oidium of the Vine is similar except that the rigid branching hairs are absent. A germinating spore is shown in the foreground. ( X 175)

After Tulasne, 1861

imported, and there is no more difficulty in this notion, or indeed so much, as in that of the introduction of such a quantity of white clover seed into the tracts recovered from the sea. . . . The Almighty produces effects of great magnitude and importance which are at first view altogether incommensurate with the causes from which they were derived/

But it was Dr. Zanardini in Venice who provided the almost melo- dramatic evidence against Oidium Tuckeri. Several workers, including Leveill£, had noticed certain little brown spots on the vine leaves after the

48

OIDIUM ON THE VINES

fungus had been wiped off, and in 1851 Zanardini showed that these were marks left where the fungus had been feeding, vampire-like, on the life-blood or sap of the leaves. * On the undersides of those spawn strands which Leveill£ imagined to creep harmlessly over the surface, he found multitudes of little suckers which penetrated the outer leaf-cells and served not only as mouths for the fungus, but as points of attachment. He called these little processes on the spawn strands 'fulcra', but later on the botanists preferred to call them 'haustoria' [vide Plate I, 4, 5 and 6], The discovery of these suckers did not prove that the fungus was a parasite, as the suckers might still only be able to penetrate moribund cells, but it made a great impression on the minds of the botanists, and more and more of them were converted to the view that Oidium Tuckeri was a parasite caught in the act, and the veritable cause of the Vine Disease.

Once the fungus had been imported into Europe, its rapid spread through the vine-growing countries, over a period of years during which the weather favoured its growth, was understandable enough. Every square inch of mildewed leaf produced some two million spores, individually invisible to the naked eye. Most of these would settle on the ground and perish, but enough would be wafted about by the wind, carried on produce, or conveyed by insects or animals, to ensure their rapid dissemination. The fungus would spread wherever it found the climate congenial and the vines to its taste. Oidium Tuckeri and the Potato Blight fungus were both almost certainly indigenous in the New World, the former on some one or other of the many species of American grapes — Schweinitz had described it on Vitis Labmsca in 1834 — the latter on the wild potatoes of Chile and Peru. How was it that they had only so recently made their way to Europe? This question arose again and again.

But had not the Rev. M. J. Berkeley himself been receiving large parcels of botanical specimens, mostly fungi, from explorers in every part of the world, since about 1833? Certainly he received consignments from North America, Australasia, Ceylon, Batavia, the Philippines, the Congo, and Peru. It was he who named and catalogued all the fungi brought back by Darwin from the voyage of the Beagle in 1836. During Berkeley's lifetime, more than ten thousand species of fungi passed through his hands, many hundreds of which he described for the first rime. Oidium Tuckeri and Botrytis infestans were only two, out of a multitude of species previously unrecorded; for Berkeley and the rest were working on a part of the earth's flora that had so far been all too scantily explored. Importation by way of museum specimens was one channel of introduction for highly undesirable alien mildews.

D 49

THE ADVANCE OF THE FUNGI

Another was the stocking of botanical gardens, all over Europe, with acquisi- tions from overseas, and the field experiments which were being made in every country on the acclimatization of foreign economic plants. Then, in those first glorious years of Queen Victoria's reign, there was a great increase in mercantile traffic. There were some who thought that the Potato Blight was brought to Europe by the early steamships, the fungus on imported potatoes surviving the shorter time at sea. But it was only in 1840 that the first Cunarders crossed the Atlantic under paddle and sail, and they were often out-distanced by the clipper ships. The Great Eastern was not launched until 1858. It was very doubtful whether the steamships really had the historical distinction of bringing the Potato Blight and the Vine Mildew to Europe from the New World. But that they came with some imported produce or other was more probable than that their spores were carried over the ocean by any singular accident of the winds.

Again, with the beginning of England's great era of commercial prosperity horticulture was in great vogue. The nobility and gentry, and especially the nouveaux riches who made their money out of the mines and the mills, indulged greatly in hothouses, winter gardens and conservatories, which they crammed with all kinds of exotic plants, from palms to aspidistras. These heavily luxurious hothouses of the prosperous were as characteristic of the period as the undrained streets and the overcrowded hovels in the industrial towns, where the infant mortality reached sixty per cent and typhus ran with the rats and crawled with the lice. Paxton's design for a 'Crystal Palace' to house the Great Exhibition of 1851 was not chosen only for its intrinsic beauty, or because the light construction of glass and iron was then about the cheapest way of covering the desired space. It glorified the hothouse as the best-available symbol of the Wealth, Culture, Art, Enlightenment, Prosperity, and self-improving Industry of England. There were hothouses everywhere, and the nurserymen's businesses were flourishing. In these hothouses, both the foreign plants and the pests and fungi brought over on them were given the very best chance to make themselves at home. The hardier plants were naturally tried out in the open, and those species of fungi which could stand the climate spread and multiplied faster than rabbits in Australia.

Nobody would ever know by what particular route the Oidium of the Vine was introduced; it might indeed have been present in Europe for decades before it was first observed on the vines at Margate in 1845; it might have come from the East — from the vines of Asia. At any rate by about 1850 it was ravaging the Grand Vines of France, and, with that other small

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OIDIUM ON THE VINES

fungus, the Botrytis Bassiana which caused the Muscardine disease of silk- worms, it was plundering the wealth of Lombardy.

Professor Duchartre, of the Institut Agronomique at Versailles, was among the first to try Mr. Tucker's sulphur remedy on the vines in France. He stirred up flowers of sulphur in water and dashed the mixture over the foliage with a garden syringe. The treatment was effective, a means was available of keeping the Oidium in check, but sulphuring the vines over hundreds of hectares of open hillside was a very different matter from spraying a few vines on the trellises or sponging down individual plants in the vineries at Margate. It meant going up and down the rows, mile after mile, with a garden syringe and a bucket of sulphur and water that had for everlastingly to be refilled. Many labour-saving variants of the process were tried. One of them was to wet the foliage with plain water first, and then blow on dry sulphur dust with a pair of specially-constructed bellows. Count Duchatel had this done on some twelve hundred acres of his vines, and the treatment was quite effective, but it was very soon found that the preliminary wetting of the vines could be dispensed with, if the sulphur dust was applied when they were moist with dew. Often enough a perfunctory dusting of the vines with sulphur, irrespective of whether they were moist with dew or bone-dry in the heat of the day, was all that the peasants could be persuaded to undertake, and then the results were sometimes disappointing. When the sulphur came in contact with the patches of mildew it caused them to dry up, and thus checked the spread of the disease. But the sulphur was washed off the leaves by rain, and the vines were growing all the time: a week after the sulphuring there would be new foliage without a particle of sulphur on it, and tender for invasion. The mildew preferred the young shoots. The vinegrowers, with their syringes and sulphur boxes, had to contend with an organism that charged the very atmosphere with its spores.

The French chemists sought for improvements on the sulphur remedy. When solid sulphur and lime were simply boiled together in a saucepan with water, the two substances entered into chemical combination one with the other, and produced an amber-coloured fluid having a very strong odour of bad eggs. This lime-sulphur, or sulphuret of calcium as it was then called, was suitably diluted in water and then applied to the vines with a syringe. It sometimes scorched the leaves a little, but it was even more deadly to the Oidium than pure flowers of sulphur. The evil smell of the compound gave those who were using it a satisfying feeling that they were applying some- thing very potent, and in fact the vapour of sulphuretted hydrogen was very toxic to the fungus — while it lasted. Once applied to foliage, however, the

THE ADVANCE OF THE FUNGI

bad smell soon passed off, and a fine deposit of sulphur mixed with carbonate of lime remained. The ultimate effect was much the same as applying flowers of sulphur, but there was something to be said for boiling the sulphur up with lime first as the fluid was easy to apply with a syringe, the sulphuret of calcium as such, had an immediate destructive effect on the fungus, and after the fluid was decomposed by atmospheric oxidation it left sulphur deposited, wherever the solution had wetted the foliage, in a film that was not easily washed off by the rain. Before 1855, Becquerel had gone one better even than this lime-suphur. Having made his solution of sulphur by boiling it with an alkali — potash or lime — he then threw the sulphur out of solution again by adding an acid. The point of this apparently roundabout procedure being that the sulphur, precipitated from solution, was in the form of such minute particles that it made a kind of milk in water. It was the white 'milk' or magisterium of sulphur; a precipitate of sulphur so impalpably fine that it entered every crevice of the foliage that was wetted by the spray,

Both chemists and vinegrowers, however, soon found in practice that everything watered does not get wet. The young grapes, for example, with their waxy surface, could be dipped bodily into water, or into these sulphur solutions, and they would come out as dry as" ever. One way of wetting a duck's back was to put the bird in soapy water. So a number of experi- menters tried mixing soap with their sulphur solutions to make them wet the young grapes. The soap was curdled by the lime in the solutions and the curds at once choked up the holes in the syringe. Some of the other pioneers in the making of chemical spray fluids were more lucky, for they added skimmed milk to their sulphur solutions, and thanks to the casein in the skimmed milk, which was an excellent 'spreader' unaffected by lime, the grapes were well wetted and the holes in the syringe remained unobstructed. The preparation of mixtures for spraying the vines threatened to become a trifle complicated, but a good lime-sulphur bouillie, even with the addition of skimmed milk, was still much easier to make than a good minestrone or Irish Stew. The great practical difficulty was in the application of liquid specifics in the open vineyards with the little squirts and syringes that were then available. It was fortunate that the simpler methods worked reasonably well; in the vineyards fine dry sulphur was dusted on to the foliage, and in the greenhouses sulphur was painted on to the hot pipes, where it volatilized and gave off sulphur fumes.

The Oidium caused the greatest havoc during the early fifties, before the peasant vine-grower had been brought to realize that the troublesome

52

OIDIUM ON THE VINES

sulphuring was .the only alternative to ruin. After that the fungus was held in check, and although it still caused great losses in bad seasons, the vintages were no longer at its mercy. At first, when the mildew had not yet obtained a footing everywhere, and there were only a limited number of sites from which it was sending forth its spores, one timely application of sulphur would sometimes have an almost magical effect; but later, when the invader had settled down to stay, and every terrace was copiously provided with it in its overwintering stages, more and more applications became necessary, and it was popularly supposed that the mildew was getting used to the poison, that the sulphur was losing its effect. In the course of long years, when the practice of sulphuring the vines had become traditional, it was found that three applications of sulphur were usually necessary: the first in the spring, when the young shoots of the vines were only from two to four inches long; the second about the time of flowering; and the third about two weeks before the 'turn* or veraison when the grapes from being green and hard began to take on the sweetness and colour of maturity.

While the vinegrowers on the Continent were contending with Oidium Tuckeri, one of its near relatives, another of the Powdery Mildews, was causing consternation among the hop growers of Worcester and Kent. The Hop Mould was no newcomer, it had been known in the hop gardens for generations, but it first became a serious plague during those 'Blight years' of the late forties, which so greatly favoured the increase of all kinds of fungal parasites on the crops. Like the Vine Mildew, from which it was almost indistinguishable in its summer stage, the Hop Mould grew on the surface of the leaves, where it was apparent to the naked eye as white mouldy patches. When it grew on the leaves it weakened the hop plants as a whole by putting a greater or lesser part of their food manufacturing or assimilatory apparatus out of action, but the irreparable damage was done when the mould grew over the 'burrs', the female inflorescence or 'flowers' of the plants, which after wind-pollination developed into the seed-cones or 'hops' of the brewers. When the Mould spread over the burrs they did not develop into mouldy hops — they did not develop at all. They shrivelled into small hard balls, covered with the fungus and there were no 'hops' either to pick or to sell.

The hop growers, in the main, held the rooted conviction that the growth of the Mould was due to some unhealthy condition of the sap of the hop plants, attributable to the weather, but they were eager enough to try the sulphur treatments which were proving successful on the vines. And here again the various treatments, if applied in time, worked very well. Fine dry

53

THE ADVANCE OF THE FUNGI

sulphur was puffed on to the hop bines, and here and there the farm pump was used to spray them with lime-sulphur.

By 1855, the majority of the hop growers were saving their hops by means of sulphur, only to run into a new trouble. The hop factors, the middlemen of the Borough, who sold the hops to the brewers, issued a manifesto. The brewers, they said, objected to 'the incorporation of sulphur in the hop plant', the slightest trace of sulphur would spoil the beer, and involve the whole brewing industry in great financial loss, if not ultimate ruin. John Lindley, in The Gardeners9 Chronicle, had one or two trenchant things to say about this precious Manifesto. He began by reminding the brewers that it was customary to burn a little sulphur under the hops when they were drying in the oast houses, to preserve them and give them a good colour. It was late in the day to discover that a trace of sulphur spoilt the beer, and if the brewers were really suffering any loss, well, he had heard of their use of picric or carbazotic acid, an intensely bitter but deleterious substance, in place of hops, and perhaps it was the picric acid that spoiled the beer, and not the good produce of the Kentish hop gardens, sulphured or otherwise. The brewers discreetly withdrew their objections, before John Lindley went into further details, and the sulphuring of the hops continued.

Sulphur was the remedy for the Powdery Mildews on the vines and the hops — why should it not also be effective against the Potato Blight? Farmers, in the main, knew nothing of the distinctions between different species of fungi; if there was a 'Blight' in the air it seemed natural to them that all sorts of crops should be affected; and if in a 'Blight* season there was an putbreak of cholera, or an unusual number of dead fish were washed up in the Humber, those happenings were probably due to the same cause. By 1855 there was still no remedy for the Potato Blight, and with the idea that sulphur might be a panacea for all kinds of plant disease, it was certainly tried on the potatoes. But it had little effect, and the thoughtful were left wondering why sulphur should kill mildews on some plants but not on others. One of the reasons was already apparent to those who studied the habits of growth of the mildews concerned. The powdery mildews on the Vines and the Hops grew on the surface of the leaves with all their spawn strands exposed, so that fumes from particles of sulphur dusted upon them, or traces of sulphur acids, could readily destroy them. The spawn of the Potato Blight fungus however was buried and protected within the leaf tissue, where no chemical could destroy it without at the same time destroying the leaf itself. It seemed, moreover, that sulphur was less toxic to- the Blight fungus than to the Powdery Mildews, and though it could certainly injure the exposed spore-bearing

54

OIDIUM ON THE VINES

parts of the fungus, which grew out from the breathing pores, and thus had some immediate effect, what was the use of that, when the unharmed root- spawn could send out a new growth in a few hours?

The sulphur which saved the vines was no remedy for the Potato Blight, and that disease continued to ravage the potato crops, to a greater or lesser extent, according to the weather, entirely unchecked. Seasons of partia 1 famine in Ireland, attributable to it, ceased to be news. The eviction of impe- cunious tenants continued, the landlords 'consolidated their position', and the practice of agriculture in Ireland was to some extent improved, as it had already been improved in England, by farming in larger units at the expense of the dispossessed. There was a search for plants that might serve as substi- tutes for the potato, and in 1854, Decaisne, of the Jardin des Plantes in Paris, was experimenting in the acclimatization of the Chinese Yam. Sets were sent to England and tried in many localities. This particular Yam, Dioscorea Batatas, proved hardy both in France and in the British Isles. Its roots were pure white, very rich in starch, and when steamed or roasted they tasted very much like the best of potatoes. They even had advantages from the culinary point of view, as they took only half the time to cook. The yield of edible roots per rod, or per acre, was also promising, but unfortunately the roots penetrated very deeply into the ground — they would go down three feet or more — and cultivation to that depth was difficult where it was not im- possible. Nature had, moreover, modelled these roots upon a most incon- siderate plan. They were rather like long misshapen parsnips the wrong way up, smaller at the top than at the bottom, so that there was no pulling them from the ground, and each one had to be carefully and laboriously excavated. The trials were not continued to the point of discovering from what soft- rots and other maladies these roots would suffer if they were grown, for example in the deep black soil of the Fens, but it was felt that the Yam, even the Chinese Yam, could never be a substitute for the prolific and easily- cultivated potato, provider of one-fifth of England's food supplies.

55

CHAPTER IV

FRUITS OF THE FUNGI

THE Oidium had not been overrunning the vines and the hops for very long before another, and a very different kind of fungal growth was noticed on the leaves of the hops. There was not only the white Hop Mould, there was also

FIG. 4. The over-wintering 'fruits', or perithecia, of the Hop Mould. ( X 300)

After Tulasne, 1861

the Red, or Brown Mould, which came later. When this Red Mould was examined under the microscope it did not present a spectacle of beautifully poised, glistening and transparent spores in vertical chains. There were, instead, a number of dark-coloured, and comparatively large sperical objects, sitting snug on the silken felt of spawn strands which had grown over the leaf surface, and furnished with long, tendril-like appendages. These objects had a certain resemblance to a clustered mass of exceedingly tiny spiders, except

56

FRUITS OF THE FUNGI

that they did not move, they were completely spherical, and each of them had more appendages than any spider had legs.

A number of small fungi were known which grew in this way, and as they were often of a reddish colour, they were called Erysiphe, from the Greek for 'red' — or, more strictly, 'rust' — as in 'Erysipelas'. No two kinds of fungi could look more different from each other than did the Oidium and the Erysiphe on the hop leaves. Both had a spawn of fine filaments which crept over the leaf-surface and drew nourishment from the outer leaf-cells by means of tiny suckers; but the spores of the Oidium which grew up in poised chains from the spawn, were naked, while the spores of the Erysiphe were enclosed and protected within the dark-coloured spheres, which were in fact, spore-cases, or perithecia. The delicate spores of the Oidium drifted off, when ripe, in any breath of wind, but the spores of the Erysiphe were released only after a long period of rest, when the hard rind of their spore-case burst and they emerged, yet further enclosed within a delicate sac — which was rather like the skin within the shell of an egg. The Erysiphe was one of a very numerous group of fungi, which Berkeley for convenience of reference had called the 'sac-fungi', or, as he would have it in Greek, the 'Ascomycetes'. The Erysiphe, said Berkeley at first, had nothing to do with the Oidium, it was a different fungus altogether.

But it was a singular fact that the Erysiphe should make its appearance on just those parts of the hop leaves where the Oidium had been growing, or was even yet erecting its chains of spores. Of course, the growth of the Oidium might produce some half-decay of the foliage on which the Erysiphe could flourish, so that the one parasite naturally followed the other. But if that were so — where were the 'seeds' of the Erysiphe lurking, until the Oidium had prepared the way for them?

Dr. Leveille in Paris was convinced that the Oidium with its exposed chains of vegetative spores, and the Erysiphe with its spherical fruits, were but successive stages in the development of one single fungus. That the Oidium was merely the Erysiphe when young. It was hard for Berkeley to admit the possibility of such a thing: he was the most industrious of taxonomists, and the existence of polymorphism — state of having more than one form — among the lower fungi would profoundly disturb the whole beautiful system of classification that was being worked out for them. What would happen to the taxonomists' noblest labours if half the minute fungi then recognized as distinct species were to be regarded as mere stages in the development of some of the rest? When so much scholarly work had been done in articu- lating names for thousands of species of fungi from resurrected fragments of

57

THE ADVANCE OF THE FUNGI

Latin and Greek, and they had all been arranged in a neat and natural order, the least that Nature could do was to keep her multitudinous inventions tidy in the pigeon holes provided for them. No! Oidium was Oidium, and Erysiphe was Erysiphe, and so they should remain, separate and distinct in saecula saeculorum. But Berkeley was not the only cryptogamic botanist with a passion for taxonomy, and certainly, so far as the Erysiphaceae were concerned, Leveille was a far better taxonomist than Berkeley. He extracted a great deal of pure taxonomical pleasure out of the Powdery Mildews, which Berkeley, because of his obstinacy, missed altogether. The different Oidiums on the vine, hop, strawberry, rose, barberry, hawthorn, oak, peach, maple and other plants, were so much alike in appearance that it was difficult to distin- guish them one from another. They had few of those exquisite but charac- teristic differences in the shapes of their parts which the taxonomists loved. When the Oidiums, however, were related to the forms of Erysiphe which followed them, then the case was very different. The spherical conceptacles or spore-cases of the Erysiphaceae, with their appendages, might have been designed by nature for the express purpose of giving the taxonomists a special and particular joy.

The Erysiphe found on the hops, for example, had long thread-like appendages, plain at the ends; while the one on the barberry had appendages which were splayed out at the ends in a most ornamental and characteristic fashion [Plate I, ia.]. Other species had appendages terminating in processes shaped like little cog-wheels, or like bits of bent-iron work on fancy gates, and these shapes were so constant and unmistakable that they served as the veritable signatures or fingerprints of the different species. On the basis of these appendages and of some characteristics of the conceptacles themselves, Leveille, by 1851, had sorted the whole of the Erysiphaceae into a number of genera or families, which he called, after their most representative members, Uncinula, Sphaerotheca, and so on. Generations later, Leveill£'s classifica- tion was substantially adopted, with envy and admiration, by all botanists. The Powdery Mildew on the vine was called Uncinula necator, and that on the hops, Sphaerotheca humuli. But at the time little attention was paid to these distinctions, and the botanists continued to refer, with less precision, to the Oidium and Erysiphe on the hops and the Oidium on the vines. One practical significance of Leveille's taxonomical labours was that they showed very clearly that the various Powdery Mildews were caused by distinct and different fungi; the one on the vines did not grow on the hops, and die one on the roses did not grow on the barberry. The importance of this fact, to farmers and gardeners, was evident, and it was a contribution towards one

58

FRUITS OF THE FUNGI

of the key realizations in plant pathology: that specific plant diseases were caused by specific pathogens. The Powdery Mildews on different plants were certainly not all manifestations, as some supposed, of one common or garden Erysiphe.

With Leveille's classical monograph, the idea that the spherical bodies with their appendages, which distinguished the Erysiphe, might simply be the fruits of the Oidium, or that the Oidium was just a young and budding stage of the Erysiphe, had already made much progress, and the 'polymorphists' were able to put forward a very plausible account of the function and purpose of the two stages in the life-history of a typical Oidium-Erysiphe mildew. In the spring and early summer, the White Mould of the Hops grew on the young foliage, each patch a microscopic forest whose 'trees' were chains of short-lived and unprotected spores. These spores spread the mould through the hop gardens, each new patch to which they gave rise producing its millions of spores in turn. But the delicate summer spores, which died in a few days if they did not come to rest on moist and young hop foliage, were not the true 'seeds' of the fungus. They more closely resembled buds, which when detached from their parent spawn would promptly strike elsewhere. They were 'bud-spores', to be called, variously, gemmae, gonidia, and finally conidia. They were not protected, as seed-spores would have to be, for lying dormant over the winter on decaying leaves or in the soil. They could not carry the fungus over, alive, from one year to another. The true 'seed-spores' of the Oidium had still to be found, and in what more likely place should they be sought than within such hard spore-cases as those of the Erysiphe, which were so well adapted for preserving their small sac-fuls of spores against decay in the winter, and for discharging them in the spring when there was new foliage on which they could grow? The conceptacles of the Erysiphe, with their long tendrils for anchorage or dispersal, were simply what they appeared to be — the perfect fruits of the Hop Mould.

But probability was not proof, and for proof it was necessary to demonstrate that some part of the supposed early growth of the fungus, the Oidium, actually developed into the fruits of the Erysiphe. And here, once again, several botanists managed to see exactly what they expected to see. At the Great Exhibition of 1851, a certain Dr. Plomley hung up a drawing of the Hop Mould which showed conceptacles developing half-way up the spore chains of the Oidium. The suggestion being that two immature summer spores in the chain, next to each other, co-operated in some sexual way and grew into one winter fruit. In 1852, Professor Giovanni Battista Amici, of the Royal Academy of Georgofili in Florence, described similar growths in

59

THE ADVANCE OF THE FUNGI

the spore chains of the Oidium of the Vine. And the brothers Tulasne in Paris made a great feature of such organs in their magnificent drawings from nature of several species of Erysiphe gathered near Versailles in 1853 [Plate I, 3]. Opinions differed as to what these intermediate sporangia might be. Some said they were the conceptacles of the Erysiphe in an early stage of development, and pointed to this as the desired proof that the Oidium and the Erysiphe were indeed successive stages of the same fungus. But Baron Cesati of Lombardy took them to be parts of a different fungus altogether, which Ehrenberg called Cicinnobolus Florentinus, growing on or among the Oidium and confused with it. The brothers Tulasne called the bodies 'pycnidia' and regarded them as a third kind of fruit, belonging to the Erysiphe-Oidium fungi, but different from both their chain spores and their conceptacles.

If there were not more of humanity in one brave error than in ten tame accuracies, the mistake of the brothers Tulasne in claiming pycnidia for the Erysiphaceae would be a poor introduction to their revealing and beautiful works. But as it happened the mistake could serve only to throw into prominence the grace and meaning of the whole. The brothers were devout Catholics, and their work of adoration, no less than of science, was to reveal in what great diversity and abundance God had given fruits to the very least of his creation, even to the most minute of the cryptogamic plants. Their researches were dedicated to the glory of God, and if from excess of zeal they sometimes saw fruits of the fungi which did not exist, that was as nothing to the great wealth of fruits which they did truly find, or to the liberation of scientific thought which followed their refusal to accept too narrow a view of the metamorphoses through which lower forms of life might pass.

The brothers Tulasne were born, and at last came to die, within a year of each other. In their botanical labours, as in their life, they were so closely associated that the name 'Tulasne' was often taken to refer to a single indi- vidual, and later workers reproducing their drawings of the fungi, the finest ever made, rarely attributed them to Charles or to Louis, but always to one, indisseverable 'Tulasne'. The close association of the brothers, their fusion, as it were, of two individualities into one being, and to one end, was reflected in the nature of their discoveries. It was their achievement to establish that the red and the black Rusts on. the wheat were two stages in the development of a single organism, and that the Oidium and the Erysiphe were equally members of each other.

Louis Tulasne at first studied for the Law, a vocation for which his retiring disposition and pellucid, natural honesty rendered him entirely unfitted; but

60

i ab ERYSIPHE Berberidis DC. 2. E. Astragali DC. 3 — 6. E. communis (Hypericearum) Fr.

7 ab E. Pisi DC. 8. E. tortilis Fr. 9—10. E. pannosa (Ross) Fr.

PLATE I. Some species of Erysiphe: a page from the Selecta Fungorum Carpologia (Reduced) L. R. & C. Tulasnc, 1861

FRUITS OF THE FUNGI

by 1842 he had found his place, and was working as an assistant naturalist at the Jardin des Plantes. Charles Tulasne practised medicine, also in Paris, and found scope for his artistic talents and his taste for botanical pursuits in making the drawings to illustrate his brother's scientific papers. They published several great memoirs in the Annales des Sciences naturelles, especially those concerning the Rust and Smut fungi afflicting cereals, but their masterpiece, and joint labour over some fifteen years, was the Sclectn Fungorum Carpologia, 'exhibiting especially those facts and illustrations which go to prove that various kinds of fruits and seeds are produced either simul- taneously or in succession by the same fungus'.1 The work was to have been very comprehensive, covering all the principal families of the fungi, but Louis's health failed him in 1864, and when the brothers retired to Hycres in the south of France, to spend the rest of their days in the service of the Church, they left behind them three perfect volumes only, which were printed in Paris by command of the Emperor, between 1861 and 1865. The text, by Louis, was in Latin throughout, which was perhaps a pity, for the matter was such that the beauties and exactitudes of the French language would have been quite adequate for its original raiment, but the drawings, by Charles, had an unearthly beauty, and were works of art that far trans- cended mere illustrations. The microscope in the hands of the brothers Tulasne was a lamp lifted in the darkness of a sub-world, amongst the strange orchards of the cryptogams. The third volume bore the inscription: 'Non nobis, Domine, non nobis, sed nomini tuo da gloriam*

The first volume of the Carpologia was exclusively devoted to the Ery- siphaceae, for which the brothers claimed no less than five different kinds of fruits or spores. There were the bud-spores of the Oidium stage, in chains; the 'pycnidia' which developed half-way up those chains and which burst, releasing charges of so-called 'stylospores' when ripe; and there were the indisputable spherical conceptacles of the Erysiphe from which mem- braneous sacs each containing usually eight sac- or *asco-' spores were released after a period of rest. The principal evidence which the brothers could offer in support of their conviction that all these fruits did indeed belong to a single fungus, was that they all appeared to arise from the same mother-spawn [Plate I]. The evidence was strong, but it did not amount to rigorous proof, for there remained the possibility that, in the confused tangle of spawn-strands on the leaves, spawn belonging to more than one species of fungus might be present. The affinity even of the Oidium to the Erysiphe was still not formally proven. But the effect of the brothers' work 1 Grove's translation, 1931, vide pages 383 and 453, herein. 6l

THE ADVANCE OF THE FUNGI

as a whole was persuasive and philosophical, it established the 'polymorphism* of the lower fungi on grounds of probability, and it set other workers search- ing amongst the successive fruits of different species of fungi for the 'perfect' fruits, the overwintering conceptacles or other protected organs in which the true seed-spores were carried. Botanists could no longer believe that the Oidium, with its mere vegetative bud-spores, was the whole of a living organism; it needed the overwintering fruits of the Erysiphe to complete it. The homage paid by naturalists of later generations to the work of adoration of the brothers Tulasne was to be found in a common agreement to regard all fungi of which the winter fruits were unknown as 'imperfect* — the Fungi Imperfecti.

The next theme of inquiry in these fundamental botanical researches which were revealing the nature of the enemies with which the practical farmer had to contend, could be conceived as arising out of the realization that parasitic fungi had fruits and true seed-spores — they were not mere growths of 'mould*. If there were fruits and seed-spores — where were the equivalents of the 'flowers'? Or where did fertilization take place? Where, in the life-histories of the Vine Mildew and the Hop Mould, were the sexual conjugations almost universally to be found in nature before the formation of fertile seeds or eggs?

No one knew why sex was necessary. It was not necessary for reproduc- tion, as parthenogenesis was common enough, especially as an alternative mode of generation, amongst many of the smaller species of living things. But Nature, or her husband, the Almighty, had not devised such a wonderful variety of highly ingenious mechanisms for copulation or pollination, and fitted them to everything from polar bears to periwinkles, merely for fun. Many of the consequences of sexual reproduction, even in 1855, could be perceived clearly enough: the sharing of the qualities of two parents amongst their offspring, the division of labour, the advantages — and disadvantages — of cross-breeding. These were apparent, not only to botanists and stock- breeders, but to every old woman who said the new baby had its father's eyebrows and its mother's nose. By 1939, a great deal more was known about the consequences of sexual reproduction, and of its mechanisms, but the wisest had still to admit that they had not the slightest inkling of the dis- positions in the ultimate structure of matter, in the nature of Life, or in the will of God, which made sex necessary or inevitable. It was still only possible to observe the how and when of its occurrence, and the limit of human philosophy was to justify it from its consequences, and to say because it does so and so, therefore it is.

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FRUITS OF THE FUNGI

It was discovered in the time of the brothers Tulasne that sea-weed laid eggs — or oospores — and that these eggs were fertilized by spermatazoids. The observation of the sexual processes, fairly complete for the flowering plants, had not then been extended to all the 'lower' plants which were pro- pagated by means of spores. They had been dubbed 'Cryptogarnia', by Linneaus in the eighteenth century, for the very reason that their reproductive processes were mysterious and obscure. Amongst the minute fungi sexual conjugation had not yet been observed, but arguing by analogy, from the sexuality of the sea-weeds and other algae, to which the fungi appeared to be closely related, it was in the highest degree probable that sexual reproduc- tion did take place amongst them, as amongst nearly all living things. Argu- ment by analogy had been the bane of science since the Dark Ages; it was never to be trusted, but it indicated directions of search.

Sexual conjugation very generally occurred when an organism had to pass through a dormant, gestatory, or resting stage in its life-history: before the formation of a seed that had to lie dormant over the winter; or of an embryo that had to live through a long period of gestation in a womb, or of incuba- tion within the shell of an egg. It was as though the dual contribution from male and female gave the embryo strength to survive the strain of hiberna- tion, or pre-natal development. When the organism had not to pass through such a stage, sexual reproduction did not always occur. A cutting from a plant would take root and grow, reproducing that from which it was taken, without any sexual process. The Canadian pond-weed could spread from end to end of a river, by detachment of parts, without ever breaking into flower, for its growth was continuous and it had no resting stage.

Once the mould on the hops was recognized as a living plant — not a product of fermentation, or of spontaneous generation, or a morbid out- growth from the cells of its host, but a plant propagated by the equivalents of buds and seeds, and even bearing fruits in which those seeds were pro- tected during the winter — then it was reasonable to study its growth for evidences of sexual conjugation. And there was a pointer to the stage at which that process might occur — not preceding the putting-forth of the bud-spores or conidia, but just before the formation of the overwintering fruits.

It was Anton de Bary, small, nervously-eager young professor of botany then making his reputation at Freiburg, who explored the sexuality of the fungi and penetrated beyond the beautiful appearances seen by the brothers Tulasne to the life-processes at work. In 1853, at the age of twenty-two, de

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THE ADVANCE OF THE FUNGI

Bary took a medical Degree, and in that same year his first and famous little book, Die Brandpilze, was published by Miiller in Berlin. It concerned the fungi which caused the Rusting and Smutting of the wheat, the oats, the barley and the rye. With this book de Bary staked his pitch in mycology, but for some years afterwards he devoted himself to the study of the algae. He could scarcely do otherwise, for the great botanical questions of the day were then centring round the development of the algae, and the works of Thuret and Bornet, Hofmeister and Pringsheim were at the leading edge of the search into the nature of life on earth. It was to be de Bary's part to extend the work on the morphology and physiology of the algae to those other spore-bearing plants which were called the fungi. The difference in mentality between the young de Bary — after he had been to school with the algo- logists — and his seniors, the brothers Tulasne on the other side of the Rhine, was illustrated by the differences in their drawings. Those of Tulasne were full, three-dimensional, emotional; those of de Bary were plain, two- dimensional, diagrammatic, stripped of every inessential detail, concentrated upon a single particular, and made with the mechanical assistance of the camera lucida. They were the product of an acute and searching intelligence, inspired not by instincts of reverence, but by desire for exact knowledge. And this knowledge was sought, not by the examination of organisms in their mature complexity, but by tracing out their development from generation to generation, from spore to spore. It was a pregnant and a new method in science; something of its sociological counterpart could be seen in the contemporary works of Karl Marx; it was the historical method applied to botanical research.

The tracking down of the sexual processes of moulds and mildews, and the subsequent phases of their development, might seem a pursuit remote from the concerns of everyday life; but when it was realized that the surest and deadliest way of extirpating any living species was to prevent its natural reproduction, then the researches into the sexuality of crop-destroying fungi, were seen to be of the very greatest practical significance.

Nature was often very gracious to human investigators who desired to probe her secrets. She left some clues amongst the simpler organisms to those that were more complex. The Erysiphaceae, the Powdery Mildews, were one of her gifts to the mycologists; they had some things in common with all the mildews causing diseases of plants, their life-histories were not very complicated; many of them were easy to find in all the stages of their growth, and their parts were exposed on the surface of leaves, where Man could watch them at his ease, once he had made for himself the necessary aids

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FRUITS OF THE FUNGI

to vision. Anton de Bary took advantage of this invitation, and finding a typical Powdery Mildew, Erysiphe Cichoracearum D.C., growing on dande- lions, which apparently suited it very well, he set himself to correct and amplify some of the observations that had been made on the fungi of the family Erysiphaceae. What was true for one of them might be true of them all — others could look into that later on — meanwhile it was of more value to science to have a thorough knowledge of one species in the family than a partial knowledge of dozens of them, and the Mildew, growing on his officinal dandelions was handy.

He waited until the autumn, when the winter fruits, the perithecia, of the Mildew were developing, and then pryed about with his microscope over the surface of small pieces of the dandelion leaves, to discover exactly how the formation of the fruits began. One of the suggestions of the brothers Tulasne had been that their 'pycnidia* — the fruiting bodies half-way up the spore chains — produced tiny 'male' sperm-spores which found their way on to some corresponding 'female* organs of the minute plant, thus starting the growth of its fertile and perfect fruits. De Bary did not find this happening at all. In fact he was sceptical about the very existence of those 'pycnidia' of the brothers Tulasne, and he showed ultimately that they did not belong to the Oidium-Erysiphe Mildews. They were growths of another fungus parasitic upon them. Little fleas had smaller fleas . . . The Erysiphes parasitized the hops and the vines, and this other fungus, to which he gave the name of Cicinnobolus Cesatii, parasitized the Oidium stage of the Erysiphe. Its spawn traversed the chains of bud-spores, and the swellings, the alleged 'pycnidia', were its fruiting bodies. This point was settled, with as much finality as could be expected, by one of de Bary's Contributions to the Morphologic and Physiology of the Fungi, published at Frankfort in 1870. Cicinnobolus Cesatii was a wonderful name for the beneficent parasite that attacked the Oidium; it rumbled round the roof of the mouth, it honoured Baron Cesati, and it was sufficiently suggestive of the bulbous and bolster-

E 65

FIG. 5. One parasitic fungus grows upon another. The fruits regarded by Tulasne as pycnidia and stylospores of Erysiphe, found by de Bary to be parts of Cicinnobolus Cesatii parasitic upon it (1869). ( X 300) After Tulasne, 1861

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like growths, John Lindley was a spoil-sport, and it was just downright nasty of him to say that the progress of botany as a science was more impeded in England by the repulsive appearance of the names it employed than by any other cause whatever. The Cicinnobolus was very interesting, most appro- priate and onomatopoeic, and it was a great advantage to have it cleared out of the way, leaving the Erysiphe fungi with only the summer bud-spores, or conidia, in chains, and the perfect overwintering fruits.

The conjugations, which looked suspiciously like sexual conjugations, from which these perfect fruits really developed, were found by de Bary to take place between strands of the root-spawn, creeping over the surface of the leaves. The fungus had no parts corresponding to the pollen and stigma of the flowering plants. Conjugation occurred at some of the places where the spawn-strands crossed. The underlying strand, which could be regarded as having female proclivities, bulged out a small protuberance, which pressed cheek by jowl with a similar protuberance from the overlying strand, which could be regarded as male. After the osculation of these two protuberances, the fruit began to form. The two original cells divided and multiplied, build- ing up the fruits in stages, by a wonderful process of cellular architecture. With the aid of the camera lucida, which made the magnified images in the microscope appear directly over his paper, de Bary had only to draw round what he saw. That was not so easy as it might sound, but it imposed a stern check on transports of enthusiasm and the drawing of things that were not there. By moving his pieces of dandelion-leaf about, de Bary was able to find fruits in every stage of development and so trace out the whole process.

With such evidence available, there was little doubt about the way in which the overwintering fruits of the Powdery Mildews developed from :onjugations between the spawn strands. But de Bary, a man of great caution md intellectual integrity, was the severest critic of his own researches. He pointed out that though the fruits appeared to arise from a sexual process he had still not yet proved that that was indeed so. He had seen the two first cells pressed together, but he had not been able to detect any transference of substance from the one to the other. It was not until thirty-three years later, when the significance of the nuclei within cells was better understood, when machines had been invented for cutting successive sections of plant organs only one or two thousandths of a millimetre in thickness, and dyes had been found that would reveal even something of the structure of the nucleus, by staining its parts different colours — it was only after great advances had been made in technique and in the understanding of the intimate mechanism of the sexual process in terms of the nuclei, that de Bary's discovery could be con-

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FRUITS OF THE FUNGI

firmed. Harper, in 1896, was able to show the fusion of 'male* and 'female* nuclei from the two parent cells.

De Bary was not mistaken, and with his observations, in 1863, the com- plete life-cycle of a typical Powdery Mildew, for example the Hop Mould, could be traced in outline. An ascospore from one of the sacs in an over- wintering fruit germinated on a hop leaf, and gave rise to a gossamer

FIG. 6. Development of the over-wintering fruits of a typical Erysiphe or Powdery Mildew, from conjugations between the spawn strands. ( x 300) After de Bary, 1863

growth of spawn or mycelium over its surface. From the mycelium there arose chains of vegetative bud-spores. Later, as winter approached, sexual conjugations took place between the mycelial strands, and from these de- veloped the only true fruits of the fungus — the perithecia. These fruits rested on dead leaves or on the soil during the winter, and in the spring liberated their charges of ascospores to start the cycle over again. That was all — except for one small addendum, that was of the very greatest practical importance: some species of Erysiphe, in localities where the winter was mild, or in sheltered places, could also survive from one season to the next, in their

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THE ADVANCE OF THE FUNGI

summer or Oidium stage, and they could do this either qn wild or on culti- vated plants. Of the dread Erysiphe on the vines, for example, only the Oidium stage was known, and it was not until 1892 that Couderc found the perfect overwintering fruits on the European vines. The perfect stages of some of the species of Erysiphe had not yet been found by 1863, but the Erysiphe or Powdery Mildews as a class had given up their mystery. Had there then been any teachers employed in bringing home to the farmers the latest scientific discoveries concerning diseases of the crops, they might have chalked up the whole life-cycle of a typical Powdery Mildew on a blackboard, somewhat as in Figure 7.

Given such information as this, by any and every means that would help him to take it in, the hop grower or the viriculturalist or the gardener would very soon be using his wits to combat the Powdery Mildews. He would see that there were other things he could do besides going to war against those multitudes of summer bud-spores with his syringes and his sulphur dusters. The perithecia, the capsules of veritable seed-spores, rested over the winter on dead foliage or scattered about the surface of the soil. They could be buried by turning over the soil, and the diseased foliage could be burnt. The mouldy hops, left on the strings and poles by the hop-pickers, would not be allowed to remain for the perithecia to ripen and be scattered by birds. When the perithecia burst in the spring they released their seed-spores to start the Mould on any young shoots of the hops they could reach. The fungus made its way up from die ground by the lower shoots and foliage of the hops as up the rungs of a ladder. The lower foliage could be removed. Sulphur could be applied to protect the young shoots. The hops were stripped down to the ground in the autumn, but it was different with the vines. The 'Oidium', in its summer stage, could survive as mycelium in some of the buds or on the bark of the stocks. The bare stocks could be treated by pruning or washing with fungicidal solutions. Taken all the year round, there were many ways of attacking a parasitic fungus, once its life-cycle was known. For the Powdery Mildews the life-cycle was known by 1863. But by whom? By a small company of learned botanists who had the advantage of being able to read French, German, English, and Latin with a sprinkling of Greek. A part of the knowledge was shared by well-educated gardeners, or employers of gardeners, who read the Rev. M. J. Berkeley's articles in The Gardeners Chronicle. The numerous viticultural societies and provincial academies of learning in France and Italy disseminated information about the Oidium of the vines. Pamphleteers and journalists got hold of a part of the story, often to confuse it with misleading notions of their own. There was

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FRUITS OF THE FUNGI

no responsible service, in England or in any other country, for giving the farmers reliable information, in plain language, on the subject of plant diseases. The botanists, and the cultured, orchid-fancying kind of gardeners, did not really care to have their botany vulgarized, robbed of its scholasticism, and deflated for the benefit of the general public.

SPRING

CONIDIA

SUMMER

ASCOSPORES

PERITHECIA

WINTER

AUTUMN

FIG. 7. The complete life-cycle of a typical Powdery Mildew - represented diagrarn- matically. Known by 1863

[The Hop Mould is not known to over-winter in its conidial stage in England. The 'Oidium* of the vines in France over-winters in both ways.]

So the farmers dismissed die learned discourses of the botanists, when they happened to overhear any of them, as the mere jabber of highfalutin scholars who couldn't grow a marrow on a manure heap, let alone manage a farm. They applied their good empirical remedy — the sulphur — usually at the right time, but often when it was too late, and persisted in such beliefs as that the Mould grew on the hops because the plants were unhealthy; that it was caused by the weather, or that it was attributable to some mysterious and indefinable 'blight' in the air.

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CHAPTER V

THE BUNT OF THE WHEAT

As bread was the staff of life, and the cultivation of wheat went back to the dawn of civilization, it was not surprising that by the time of young de Bary and the brothers Tulasne, the diseases of wheat had received more attention than any other plant diseases whatsoever, notwithstanding all the then recent inquiry into the nature of the Potato Murrain and the Vine Mildew. In Europe, the Rust was sometimes very destructive, but by far the most generally prevalent affliction of the wheat was the Bunt, the Stinking Smut, la Carie de blcs. It had been a despoiler of the grain since time immemorial. The 'blasting and the mildew' mentioned in the list of abominable curses for disobedience of the Commandments in Deuteronomy xxvm, almost cer- tainly included the Bunt or Stinking Smut of the Wheat. But the Bunt, unlike the equally ancient Rust or Blasting, was never epidemic; it did not sweep as a plague across the wheat fields of a continent; it was endemic, and like poverty, ever-present. In any year it was to be found, very bad in some fields and in some localities, less so in others.

In a ripe but bunted ear of wheat the grains were swollen and black, still whole, but with all their inner substance transformed into a pulverulent mass. Where there should have been healthy kernels at harvest, there were so many black 'Bunt-balls' or 'butts', which when broken had an unpleasant and very strong smell, not unlike that of decaying fish, or herring brine. The Bunt- balls ripened at the same time as the grain, and when the bunted wheat was put to the flail, or threshed in the threshing machine, many of these Bunt-balls burst, and the black powder which they contained contaminated the clean grain. To pick out the bad ears was impracticable, the bunted wheat was reaped and threshed with the good. The flour, in consequence, was dis- coloured and of unpleasant odour and taste. The bread made from it was not poisonous and it was eaten by the poor. It was not known to cause any such disease as did the ergoted rye, but where there was much Bunt in the wheat it would fetch only a very low price and much of it had to be fed to animals on the farm. In England, bunted wheat was commonly bought up by the gingerbread makers, who disguised both the bad colour and the taste with their ginger and treacle, and no doubt gilded the product on occasion.

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THE BUNT OF THE WHEAT

The Bunt was common enough but, already in 1855, the appearance of more than an occasional bunted ear in a wheat field was rather a sign of negligence on the part of the farmer than an unavoidable calamity, for simple means of preventing the disease had been found, and had long since been adopted in farnt practice. For the story of how these means were discovered it was even then necessary to look back over a hundred years, and to appre- ciate the work of two men, experimenters of rare genius, who between them anticipated half the 'technique* of modern plant pathology.

The first was Mathieu Tillet, sometime Master of the Mint at Troyes. Tillet was only a farmer in a small way, he had no systematic training in the botany of his time, nor in what were then regarded as the enlightened principles of agriculture. But he chose to devote his leisure to experiments on the crops, and to writing dissertations upon them, by way of developing the powers of his mind. When, in the year 1750, the Academy of Arts and Sciences at Bordeaux, of which Tillet was a member, offered a prize for the best dissertation on the cause and cure of the blackening of the wheat, which was then sorely troubling the farmers in the locality, Tillet responded eagerly to the invitation. He was fascinated by a notion that making practical experi- ments might be of material help in solving difficult problems of natural philosophy. The problem proposed by the Academy provided him with something on which to try out his idea, and when it came to publishing his dissertation he apologized with great tact and humility for placing before those more learned than himself certain conclusions which were based on mere observation and experiment, and not on reasoning from accepted philosophical tenets. He remarked that 'the experiments a man himself conceives and performs have something to their advantage. They are valuable to him who performs them, hence he follows them closely, and as they become familiar, so they strike him in different ways, and by increasingly stimulating his curiosity cause him to multiply his observations'. And, of course, they enabled a man to see with his own eyes those things which he was talking about.

Tillet's 'Dissertation sur la cause qui corrumpt et noircit les grains de bled dans les fyis, et sur les moyens de prevenir ces acddens was awarded the Academy's prize — of which the humble provincial experimenter was immensely proud.

It was then variously supposed that the corruption of the wheat in the ear was due to sunstroke — the sun shining too brightly on ears heavy with water after rain; to morbid and sporadic effects of pestilential mists; to poor drainage of the soil; to unpropitious influences of the moon or the weather at the time of sowing; to the attacks of insects; to the use of sheep manure;

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or to a principle, at once ethereal and honey-like, called Enmitture, which was supposed to fall out of the sky even in good weather and corrupt the young kernels. Over the Channel, the Englishman, Jethro Tull, had been strongly of opinion that the disease was due to some decay of the seed in wet ground, and he advocated a preservative for the seed which some people claimed to be of magical efficacy and others declared completely useless. The alleged preservative was discovered by the accident of planting seed which had been salvaged from a shipwreck, and it consisted in sprinkling the seed grain with a solution of sea-salt and then drying it with lime. There were a great many theories at offer as to the cause of the corruption, and most of the agricultural writers of the time 'quoted the opinion of the younger Pliny, who said nothing decisive on the point at issue'.

Tillet succeeded in putting practically every one of the theories to the test of direct experiment. He began with the sunstroke and wet-ground theories, planting the same seed in pots which he (a) kept normally watered and well- drained, and (b) flooded with water four times daily over the whole growing period. There was no difference in the number of bunted ears. Nor did the exposure of the 'water-logged' plants to the brightest sun produce any sign of the Bunt where it was not already apparent. So much for that. The insect theory at first seemed to him more plausible, for when pulling apart the chaff of bunted ears in the field, he several times observed small black insects running out. Indeed it seemed hardly necessary to seek further — black insects, blackened grain. But it was necessary to be sure; and he had also noticed that seed, dirtied with the dust from the Bunt-balls, seemed to give rise to plants with more bunted ears than there were amongst those which had arisen from clean seed. He was convinced that the black insects were the real culprits — but he would be thorough, he would put all the rest of the possibilities to the test of experiment just the same.

He had a piece of land, five hundred and forty feet long by twenty-four feet wide, in the middle of a large field on which wheat was grown by several of his neighbours. He began by dividing his piece of land crosswise into five equal parts. The first of these he manured with pigeon droppings, the second with sheep manure, the third with night-soil, the fourth with horse and mule manure, and the fifth he left without any manure at all, as a check, or, as it would be called in the important-sounding jargon of the twentieth century, a 'control'. He next divided his piece of land lengthwise into four strips, each five feet wide, using the four feet of width which he had over for paths between the strips. The four strips he reserved for seed treated in four different ways. The first for seed deliberately blackened with dust from the

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THE BUNT OF THE WHEAT

Bunt-balls; the second for seed treated with sea-salt and lime, the fourth for seed treated with lime only or with lime and nitre, and the third and last, once again the 'control' for apparently clean seed that received no treatment of any kind. His piece of ground was thus divided into twenty equal smaller plots, and, of these, plots which had received each of the five different manurial treatments were reserved for each of the four differently-treated sorts of seed. He had one of his twenty plots for untreated seed manured with pigeon droppings, another for deliberately 'bunted* seed manured with night-soil, and so on. The ingenious, plait-like lay-out of the plots made it possible for him to compare the effects of all the several combinations of seed and manurial treatment, simultaneously.

But he went further even than this, for he next subdivided each of his twenty plots into six equal strips, which he sowed on different days to test the effect of different weather conditions at the time of sowing. In the end he had therefore one hundred and twenty small plots, each eighteen feet by five feet, on one of which he had limed and salted seed, on unmanured soil, planted on a wet day; on another, deliberately bunted seed, manured with pigeon droppings, planted on a fine, dry day, and, once again, so on, A hundred and twenty combinations of the three variables, differing amongst themselves by only one variable at a time. It was all winter wheat, and the plots were duly sown, in accordance with the plan, on October i6th, 22nd and 27th, arid November 3rd, roth and 22nd, 1751.

Tillet watched and pondered over his plots as the wheat came up and as it grew. He made notes. In the spring and summer of 1752 he was about the plots every day, giving his whole mind to them, and finding, in attempts to account for the differences they presented, all the intellectual perplexities and satisfactions of a grand checker-game with Nature. He had ruled out the board, and the pieces were the healthy and the blackened ears of wheat. It was no ordinary kind of checker-game, for Nature disposed the pieces, and it was for him to worry out the rules, from the position of the pieces on the board.

The solution was simpler than Tillet had any reason to expect. All the plots which had been sown with seed deliberately contaminated with dust from the Bunt-balls showed a predominance of bunted ears. All the plots sown with good but untreated seed showed a few bunted ears. All the plots sown with seed which had been treated with lime, lime and salt, or lime and nitre, were practically free from bunted ears. The riddle was solved then, and for all time: the Bunt, la Carie de bles, was caused by the infection of the seed-grain by the black dust from the Bunt-balls when they broke under the

73

THE ADVANCE OF THE FUNGI

flail. The kind of manure applied to the land, and the weather at the time of sowing made no appreciable difference to the number of bunted ears. The black insects had nothing to do with the Bunt, nor had the cold mists in the summer, for they had chilled both good and bad ears alike. The treatments with lime and salt, or nitre, were effective, but they did not act by preserving the seed in the wet soil — they removed or counteracted some infective or mortiferous principle in the Bunt dust which adhered to the seed.

It was a magnificent piece of experimental work for 1752, or indeed for any time, and during the next two seasons, Tillet not only repeated his trials and confirmed his first results, but amplified them with much subtlety. If the seed was contaminated by the Bunt dust, why not the straw? Might not the bunted straw, which found its way back in farmyard manure to the soil, contaminate the seed after it had been sown? Tillet had an old Spanish horse, which he now made an unwilling participant in his experiments. The horse had to eat only bunted wheat and it was littered with bunted straw. A pile of 'suspected' manure was thus accumulated and kept apart. The horse was then fed on clean wheat and littered with clean straw, so that a supply of 'clean' manure was obtained for comparison. Straw blackened with Bunt dust was also chopped up and added to each of the other kinds of manure. Tillet thus found, again by direct experiment, that clean seed sown in plots treated with manures which contained infected straw, gave rise to slightly more bunted ears, than in those plots where straw had been absent from the manure, or free from Bunt dust. He next provided himself with a bag of Bunt dust and sprinkled it along the drill at the time of sowing or broadcast it over the soil. Again when the wheat came up there was an abnormally high proportion of bunted ears.

Near Tillet's plot of ground there was a field belonging to the Carthusian Fathers, and he watched the labourers at work there, sowing wheat. One evening, when they had gone away, he trespassed on the good Fathers' land and carefully sprinkled a square patch of it with Bunt dust which he had to spare from his legitimate experiments. The next summer there was a con- spicuous square patch in that wheat in which an extraordinarily large pro- portion of the ears were bunted. Tillet strolled over, with his hands in his pockets, and asked Father Portier what he thought might be the cause of the phenomenon. - He replied without hesitation that it was due to an evil wind in the mist. 'Och aye,' said Mathieu Tillet, or words to that effect.

Having proved beyond all doubt that the Bunt of the wheat was a seed- borne disease, Tillet sought for the most economical means of preventing it. He treated his seed with various lyes — alkaline solutions obtained from the

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THE BUNT OF THE WHEAT

ashes of plants; and he also tried ammonia, obtained in the old Roman way, by leaving tanks of bovine or human urine to putrefy. He found that the lye solutions gave the best results, but they cost money — two or three sous per bushel of seed treated. Even that would be too much for most of the farmers, and he recommended the use of the putrid urine, which was almost as good, and which cost nothing whatever. Tillet desired that his neighbours should profit by his work, which was for the community and not merely for the Academy, but he was wise enough not to lecture the farmers. He contrived that they should make experiments for themselves, so that it seemed to them that the discovery of the cause and cure of the Bunt was their own. He was as good a psychologist as an experimentalist, for he said: 'When one knows the characteristics of the farmers, their sometimes poorly comprehended economies, their predilection for their own practices, and their hesitancy to receive anything not conceived by someone in their midst, one feels that it would be necessary, if he would assure himself of their tractableness, to put them to no expense in acquiring something of value to them, to avoid requir- ing their departure from a certain round of operations to which they are committed, and to trick them, so to speak, in abandoning them, to look into scarcely any difference between the precautions one counsels them to observe and those which they have always been constrained to practice/1

Tillet's discoveries solved one riddle, only to posit another. How was it that a little dust from the Bunt-balls on the wheat seed caused the ears to be bunted in the following year? The wheat plants showed no sign of disease until the ears began to fill out, and even then the only abnormality was in the ears, which grew somewhat stumpy, with grains which were at first soft and bluish, and later blackened and swollen, till at harvest they were filled with the Dead Sea dust. What was the connection between the Bunt dust on the seed and the production of bunted ears? What was the Bunt dust? And how did it corrupt the wheat plants? These were questions that Tillet could not answer. He examined the dust under his (eighteenth- century) microscope and found it to be composed of innumerable, minute, spherical bodies, very uniform in size. He did not clearly recognize them as fungus spores, although he was very near the mark. * Possibly', he said, 'we shall conclude by considering them as the result of some hidden internal con- tamination, differing little from that which is to be observed in Lycoperdon or the Puff Ball, the intact envelope of which encloses a black powder, which when viewed under the microscope also presents an infinitude of round and coequal particles.'

1 Humphrey's translation, 1937. 75

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In 1760 the wheat gave meagre crops in France, bread was very dear; there was widespread misery and privation. The savants everywhere solicited the authorities to inquire into the evil, and thus the Agricultural Society of Paris came into being. It was found that la Carie was the most redoubtable cause of the failure of the wheat crops; often it was responsible for the direct loss of a quarter to a half of the grain, and all the rest was more or less tainted by this Stinking Smut. To the newly formed Society belonged the credit of introducing into French agricultural practice the steeping of seed wheat. The knowledge which Mathieu Tillet sought to share with his neighbours was carried into every province of France. After Tillet came the Abb£ Tessier, who, by about 1783, had tried everything he could think of, from brandy and creme de menthe downwards, for the prevention of la Carie. It was Tessier's great contribution to stress the importance of lime. In whatever solution the wheat was steeped, it was always advisable to dry it afterwards with lime. The English lime and sea-salt was preferred, but even washing in plain water would do much good, if it was followed by lime. Whether the lime was used in the steep, or as a drying agent, it was the essential ingredient in all the most effective treatments, and after Tessier the whole operation of treating the seed wheat, no matter what materials were actually used, became known in France as le chaulage. With the progress of It chaulage the great losses from the Bunt gradually diminished over the whole country, for not only was the grain saved bukthere was cleaner seed.

In 1807, Benedict Prevost, Academician and Professor of Sciences at Montauban, announced two further discoveries. They directly concerned the Bunt of the wheat, but they were of fundamental significance in the whole art and science of preventing diseases of the crops. He found, in fact, two keys; one to the nature of many plant diseases, and the other to their control. But it was not for over seventy years, until after 1880, that the keys of Benedict Prevost were really turned in their locksv

Prevost's apparatus included a microscope — which confused the appear- ance of the objects observed with all the colours of the rainbow — a drinking glass, a copper alembic, a thermometer and an old copper pannier covered with verdigris. He began by shaking some of the dust particles from Bunt- balls into the drinking glass, and soaking them in a little water to find out what action water had upon them. He took out drops from time to time and peered at them through the microscope. The particles grew. They had life. They developed into queer microscopic organisms, half vegetable, half animal, in appearance. They were little spores or seeds. When they had been in the water for about three days, a short stumpy transparent tube grew out

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THE BUNT OF THE WHEAT

from them, which was surmounted by a tuft of small shoots, star-like, at the top. As they continued to grow, these shoots — the rays of the star — leng- thened into a plume, so that the tiny plant had some resemblance in form to a lily or an onion, with a 'bulb' at the bottom, a straight 'stem5, and then long narrow leaves splayed out. The colourless, lily-form threads seemed to reach out and sway in the water, so that after a while they looked less like the leaves of a plant than the tentacles of a polyp, or of one of those .small transparent hydra which hunted water-fleas. In the end, these 'leaves', or filaments, or tentacles — whatever they were — appeared to mat together into a limp wick, and to put forth small buds or fruits.

FIG. 8. The germination of Bunt spores in water. ( x 200) (original scale). .

After B£n£dict Prevost, 1807

Prevost recognized and plainly asserted that the minute reticulated spherical bodies which composed the Bunt dust were the 'seeds' or spores of a microscopic plant, and it was this living plant — and no mysterious virus or poison — which caused the disease of the grain. This realization, reached forty years before Berkeley put forward his fungal hypothesis to account for the Potato Blight, was the first of the keys of Benedict Prevost.

And Prevost saw, too, how the Bunt fungus, or hydre vig&tale as he called

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THE ADVANCE OF THE FUNGI

it, might attack the seedlings of the wheat plant. The Bunt spores, which, as Tillet had discovered, retained their vitality for many years when kept dry, germinated in the moisture surrounding the wheat seed in the soil, much as they germinated in his drinking glass. They would give rise to the same tiny, colourless plants, the tendrils of which would obtain entry into the seedlings, probably before they reached the surface of the soil. The parasite would then thread its way up the culm of the wheat as it grew, until the grain was form- ing in the ear, when it would fructify within the skins of the grains, utilizing their substance for the formation of its own dusty spores. Prevost was unable to discern any mycelial threads of the fungus actually traversing the stems of the wheat, but he surmised that they must be there. The develop- ment of spores within the wheat kernels was apparent«enough. He measured the spores under the microscope with a divided scale and estimated that there were about one million of them in each Bunt-ball.

Once the cause of an evil was known it was easier to find remedies for it. Prevost had a simple but very delicate test for any chemical steeps which might occur to him, or which were then in use, for treating the seed wheat. He now knew what they had to do: they had to kill or inhibit the germina- tion of the Bunt spores, without killing or inhibiting the germination of the seed wheat. To determine whether any given chemical would or would not stop the germination of the Bunt spores was simple; he had only to add the chemical to the water in his drinking glass, put a few Bunt spores into it, and then examine them from time to time under the microscope. He looked about him for more effective steeps than the lime and salt, or lime and urine, which the farmers were using.

The discovery of the ideal substance was the result of chance plus sharp observation and a thoughtful habit of mind. He noticed that for some reason the Bunt spores did not germinate very well in the distilled water from his copper alembic, and while he was trying to account for this, a friend invited him to inspect a crop of wheat, which had been raised from seed treated in a way usual in the district, but which was quite remarkably free from bunted ears. When strolling through the farmyard, Prevost noticed an old copper pannier, and his friend told him that it was handy for use in le chaulage. It was his custom to put the seed wheat into it, and then dip the whole into the pot containing sheep's urine and milk of lime.

Copper alembic, copper pannier ... It seemed a fantastic idea — but was it possible that water, by mere contact with copper metal, could acquire some property which made it poisonous to Bunt spores? It was unlikely indeed, but it could be put to the test. Prevost returned to his experiments, and this

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THE BUNT OF THE WHEAT

time he put a small square of polished copper metal into the water in which the spores normally germinated very well. The spores still germinated, but the subsequent growth of the microscopic plants was arrested at an early stage. Their fine threads wilted and died. He repeated the experiment with pieces of copper covered with verdigris, and the effect was much more pro- nounced. The Bunt spores were sensitive to minute traces of copper in the water.

It at once occurred to him to try copper acetate, which could be made by dissolving verdigris in vinegar, and copper sulphate, the commonest and cheapest soluble salt of copper. He found that as little as one part of copper sulphate in two hundred and eighty thousand of water sufficed to prevent the germination of the Bunt spores. Even a dosage of one part in a million of the copper salt — corresponding to one part in four million of copper metal in solution — was sufficient if the seed was steeped for a few hours. The copper acetate was about equally effective. Other experimenters had tried dangerous poisons for the treatment of the wheat: arsenic and bichloride of mercury. Prevost had discovered that the element copper, so little poisonous to man and other animals that pumps and saucepans were made of it, was deadly to the spores of the Bunt fungus at one part in four million of water. This discovery of the unique effect of copper on fungus spores was the second of the keys of Benedict Prevost.

At the beginning of the nineteenth century there were one or two of the great agricultural reformers still left in England, who made it their business to watch for all important discoveries on the Continent. This scouting was sadly neglected later, but Sir John Sinclair, Sir Joseph Banks and Arthur Young did not miss much. A copy of Prevost's memoir, with its three engravings tinted in water colour, was among Sir Joseph Banks's most treasured possessions, later preserved for the nation in the library of the British Museum. l Not only was the copper sulphate steep soon made known in England, but Sir John Sinclair, in one of his journeys to pick up hints from farm practice in the Netherlands, even came across one of the anticipations of Prevost's discovery. There was nothing new under the sun. A Mr. Van- doorslair, in the district called the Pays de Waes, between Ghent and Ant- werp, informed him of a preparation sold to the peasants for many years by the druggists of Malmes for the prevention of diseases of the wheat. This remedy, which was very little known in the surrounding districts, and not at all to the philosophic world, turned out to be nothing other than acetate of copper in powder. One half of an English pound of it, for six bushels of 1 Fig. 8, herein, is drawn from that copy. . 79

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wheat, was mixed with as much human urine as would enable the light bunted grains to be floated off. The remaining seed was then steeped in the mixture for three hours and subsequently dried, with or without lime. Thanks to the watchfulness of Banks and Sinclair, the copper treatment was even adopted in England long before it became common in France or Germany. According to the Rev. M. J. Berkeley, writing in 1856, its use was preferred and had become traditional among the English farmers, while on the Con- tinent it was used only here and there, until the treatment was revived and further investigated by Julius Kiihn.

In practice the farmers used much more copper sulphate than was just sufficient to prevent the germination of the Bunt spores. They used a pound in ten gallons of water, but as the 'bluestone' cost only a few pence a pound, the cost of material for the treatment was trifling. The serious objection to it was that the bluestone solution, left to dry on the seed before sowing, caused considerable injury, particularly to those grains which had been cut or bruised in any way during the threshing. This disadvantage was largely overcome by steeping the grain in baskets for a carefully limited time, and then pitching it on to the floor of the barn and shovelling it over with dry slaked lime. The lime served the triple purpose of 'neutralizing* the excess of copper sulphate, encrusting the grain with an insoluble cupric deposit which tended to preserve it in the soil, and of drying the grain in readiness for the sowing.

If the first use of copper sulphate for the prevention of a fungus disease of the crops was of the very greatest historical interest, so also was the use of copper sulphate in conjunction with lime. In France, there was another very effective treatment for the wheat, which depended upon the use of lime, but which required no copper. It was called 'The Absolute Preservative of Mathieu de Dombasle'.

Mathieu de Dombasle, who was born in 1777 and died in 1843, did much to improve the practice of agriculture in France. Of which Arthur Young had said: 'My God, give me patience to see so fine a country, so favoured by heaven, treated so badly by men.' During the Napoleonic wars Dombasle started the French sugar-beet industry, and when the price of sugar fell, after 1815, he turned his hand to the improvement of agricultural implements, invented the Dombasle plough, and was associated with the ititroduction of threshing machines. He founded a famous college of practical agri- culture at Roville, a village on the Moselle between Nancy and Epinal, and he wrote many books and pamphlets on the political economy of the land. In his Calendrier du Bon Cultivates, he described the operations, the year

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round, for the good cultivation of the crops of France, setting forth in a very cogent and straightforward way the best agricultural practice of his time. His philosophy was summed up in one sentence: 'La charrue est dans tons les lieux la premiere base de la richesse publique.' But it was folly when improving the tillage of the land to neglect any measures that could be taken to prevent the wastage of crops by disease. There was still far too much of the Stinking Smut in the wheat. He improved upon the sea-salt and lime of Jethro Tull by substituting Glauber salts (sodium sulphate) for the sea-salt. The grain, placed in heaps on a stone floor, was watered with an eight per cent solution of the salts and then dried with lime. The treatment caused less injury to the grain than did that with copper sulphate. No doubt the Glauber salts, per se, had some effect on the germinating Bunt spores, but once again it was neces- sary to remember the lime, which did more than dry the grain. When sodium sulphate and lime were brought together in a moist state, they did not remain sodium sulphate and lime. The sodium and the calcium changed partners, and, presto, there was a magma of gypsum and caustic soda. The Glauber salts were relatively innocuous, but the caustic soda was as caustic as its name implied. Untreated seed wheat, in one of Matliieu de Dombasle's instructive experiments, gave rise to a crop with 486 black and carious ears per thousand. Seed from the same source, after treatment, gave only 2 bunted ears per 1000. A saving of half the crop. Le chaulage was unquestion- ably one of the most important operations in the cultivation of wheat.

By 1847, when the Potato Blight was still a mystery, and systematic investigations in the whole field of plant pathology had yet to begin, there was the inspiring example of one serious disease of the crops, of which much was already known, and for which a number of remedies had not only been found, but adopted in practice. At the expense of a small proportion of the seed which always failed to come up after the chemical treatments, the Bunt of the wheat could be almost entirely suppressed by human agency.

But the Bunt of the wheat was only one of a very numerous group of fungus diseases which afflicted the cereal crops. It was one of the smutting, charring, burning or blasting diseases which were sometimes referred to, collectively, by an old name, common to both English and German — the 'Brand' diseases of cereals. Hence the title of Anton de Bary's Die Brandpilze of 1853. Although so dependent on moisture for their development, the Brand diseases had always been likened — with some stretching of the imagination — to the results of burning or fire. They fell into two fairly distinct categories: the Smuts or Dust-Brands, which, according to their kind, either converted the substance of the grain alone into black dust or

F 81

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reduced whole ears to charred skeletons; and the Rusts, or Rust-Brands, which streaked the straw and leaf-blades of the plants with dusty pustules which had the colours of charcoal or flame, and which, by exhausting the plants and depriving the ears of their alimentary chyle, caused shrivelling of the grain. The Smut fungi, which went by the Latin name of Ustilago, and the Rust fungi, typified by the Uredo, were almost inextricably confused together by the botanists before the eighteen-forties, when first the good doctor L6veille, and then the brothers Tulasne, entered upon the mighty labour of sorting them out. Many species, or bits of species, of both Ustilago and Uredo were known under a bewildering multiplicity of scientific and popular names. The brothers Tulasne sought to discover which 'fruits' or kinds of spores belonged to which, and, by careful comparative studies, to confirm Leveille's separation of the two families. The next important ad- vance in knowledge of the Bunt fungus was made in connection with these studies, which were published in the Annales des Sciences naturelles in 1847 and 1854.

The brothers began by confirming the difference, long since appreciated by the farmers, between the Bunt or Cane of the wheat, and its black sister, the Charbon, or (Loose) Smut. Where the Bunt-balls remained intact until threshing time, the spores of the Smut were ripe when the wheat was in flower, they were blown about the field as a black dust by the wind, the chaff came away, and only the bare and blackened rachis of the smutted ear remained at harvest. The Smut fungus was not the same as the Bunt fungus, and to make it quite clear which they were talking about, the brothers named the Bunt fungus Tilletia caries, after Mathieu Tillet, and reserved the generic name 'Ustilago' for the Loose Smuts. Fortunately the Loose Smut — on the wheat — was not nearly so serious as the Bunt. Berkeley mentioned in 1856 that the English farmers took little notice of it, and even had a superstitious belief that a little Smut in a wheatfield augured well for the crop in other respects. They said that, much as they said that when the moon was on its back it was filled with rain. Sometimes, when the moon tipped its contents, and the Smut was unusually bad, there would be 'black rain*. Clouds of spores, lifted by the wind, were washed down again. But black rain was rare enough for it to be regarded as a supernatural occurrence. Usually there was not much Smut and it did little harm. It had not the unpleasant fishy smell of the Bunt, and as the spores were blown away before the wheat was harvested they did not contaminate the whole run of the grain. There was only the direct loss of the smutted ears.

The Loose Smut was much more serious on the oats and barley than on

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the wheat, and it was a terrible plague of maize. There were a number of Loose Smuts, caused by different species of Ustilago, affecting the many different species of wild grasses and cultivated cereals. They could not be combated by the seed treatments then in use for the Bunt of the wheat, for the reason that they infected the seed in an entirely different way. And this was not discovered until much later in the nineteenth century. There was no remedy for the Loose Smut diseases until certain of the sterilization processes arising out of the researches of Pasteur were adapted for use against them. Meanwhile that obliging guinea pig of the mycologists, Tilletia caries, cause of the Bunt of the wheat, was made to betray a few more of its secrets.

With a very much better microscope than had been available in the time of Prevost, the brothers Tulasne re-examined the germination of the Bunt spores. The outstanding question was: how did the Bunt fungus obtain entry into the wheat plant? The only openings in the young stems of the wheat were the stomata or 'breathing-pores', and they were smaller than the Bunt spores, which could not therefore pass directly into the interior. In this form the question was naive, and Prevost had shown that it would pro- bably be the threads from the spore after germination which penetrated the seedling, but this part of Prevost's work was scarcely understood in his time, and in 1847 there were still many who believed that the spores contained granules small enough to sift through the stomata, as grains of pepper might be introduced into a pepper pot through the holes in the top.

When the Bunt spores germinated the stumpy tube which they first pushed out was quite small enough in diameter to enter the stomata, but the actual development of the microscopic Bunt-plants before any parts of them penetrated the wheat was much more remarkable than that. The star-like sprouting of threads at the end of the stump and their growth into a kind of plume or aigrette were as pictured by Prevost. But when the plume was

1 The stoma (of the coleoptile) is here sketched from a figure by John Percival in The Wheat Plant, Duckworth, 1921.

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FIG. 9. One of the first stomata1 of a wheat seedling, with Bunt spores to the same scale (x 300). How does the Bunt obtain entry?

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examined in greater detail something very curious was to be noted about its threads. They were linked together in pairs by small cross-pieces, so that each pair was like an elongated letter H. Why? Anton de Bary suggested, a little later, that the linkages represented sexual conjugation, and that the threads, alternatively male and female, paired off together while yet on their parent stump. However this might be, when all the plasm in the original

-•%

FIG. 10. The Germination of Bunt Spores in water, (x 460) (original scale).

After Tulasne, 1854

spore, swollen by absorption of water, had been squeezed along the stumpy tube into these paired threads, they broke away and began to undergo further developments on their own. They put out finer tubes in turn and squeezed their plasm into fruit-like bodies, sporidia, or secondary spores. These mere bits of plasm-in-a-membrane, after detachment, continued to grow, putting out more groping threads and even tertiary spores. The H-shaped elements on their mother-stumps, and the various detached bits of plasm in all their extrusive metamorphoses, were endowed with movement. They swayed and humped and pushed themselves about in the water. Louis and Charles Tulasne had been very sceptical about the reference to this movement in

THE BUNT OF THE WHEAT

Pr£vost's Memoire; they did not altogether believe in vegetable hydras. But there it was — the movement was apparent enough with the high magnifica- tion provided by their excellent microscope, and their eyes did not deceive them.

It was now possible to visualize, even more graphically than did Prevost, the way in which the.Bunt fungus could enter the wheat seedlings, when the Bunt spores and the wheat seed were germinating alongside each other in the soil moisture. Once within the tissues of the seedling, the vegetative part of the fungus would consist of fine mycelial tubes traversing or winding about among the cells. Leveille had observed such intercellular mycelium belonging to other kinds of Brand fungi. The origin of the anticipated mycelium could be seen by watching the Bunt spores germinating in drops of water. The oddly-shaped sporidia were constantly pushing their thin enveloping membranes into new hollow threads, down which the living plasm passed to form new growth. It was only necessary for these fine tubes on the sporidia to be insinuated into the stomata, or to push straight through the soft cell-walls of the young seedling, and then the plasm in the bulb-like part of the sporidium, outside, would be squeezed along the tube which had pricked an entry, to lengthen into a mycelial filament within.

All this, however, was even yet surmise, and when at last it was actually seen to happen, a turning-point in the history of mycology was passed. When the germ-tube of a fungus spore was first seen in the field of the microscope stabbing its way through the epidermis of its host plant and originating mycelium within, then the parasitism of that fungus was proven at the bar of science. The first endophytic fungus ever observed in the act of penetration was neither Tilletia Caries nor the Potato Blight fungus, but a little Pythium which attacked fresh-water algae. The crucial observation was made by Ferdinand Cohn, in 1854. And by 1858, Julius Kiihn, in Silesia, had seen the collar of the wheat plant penetrated by the Bunt fungus itself, and the copious growth of its mycelium through the soft tissues of the stem.

CHAPTER VI

'VEGETABLE PATHOLOGY'

WHEN the Royal Agricultural Society of England was incorporated in 1840, the coming necessity for the establishment of a branch of agricultural science, to be concerned especially with the diseases of the crops, was clearly foreseen. There were two ways of increasing the produce of the land; the first was to increase the obtainable yield by good cultivation, selection of stocks and herds, drainage, rotation, and the skilled use of manures and fertilizers; the second was to decrease the wastage of produce due to pests and diseases. Both endeavours had equally to be encouraged if the landowners and the farmers were to prosper and the rapidly-increasing population of the country was to be fed. By way of preface to the first number of the Society's Journal, published in January 1840, there was a responsible survey, by Philip Pusey, M.P., of the state of agricultural science in England in 1839. As an example of the national gain which might result from the Society's work for the advance- ment of agriculture, under the banner of 'Science with Practice', he men- tioned that the average yield of wheat in England was then 26 bushels per acre. If this average could be increased by only one bushel per acre, * the gain, with wheat at its then current price, would be ^ 1,200,000 yearly, equivalent to a capital sum of £24,000,000.

'But', he went on, 'we have to look at least as much to the prevention of loss as to increase of profit . . . Little does the sanguine calculator upon paper know of the farmers' real anxieties and frequent disappointments — • of the blights and the rusts and the mildews; the insects and the fungi, which, falling as if in an unseen cloud on his fields, impair, if not destroy, the vegetative power which he has so carefully and expensively endeavoured to nurture. There is no department of agriculture in which minute inquiry is more needed than this: first to examine accurately the various diseases of plants and to note the habits of the animals which prey upon them; then to ascertain if possible the remedies that may be applied; and the followers of kindred sciences may be fairly invited to aid us in the formation of this branch of knowledge, which may be called agricultural pathology.'

1 When the Society celebrated its centenary in 1939, the tcn-year-average yield for wheat in England and Wales was about 32 bushels per acre. A part of this increase was, however, due to the fact that the cultivation of wheat was then in the main restricted to the very best of the former wheat land.

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'VEGETABLE PATHOLOGY*

The words were well spoken, but for many years little was done; no real start was made. And, indeed, it never fell to the Royal Agricultural Society to take the lead in the promotion of this branch of agricultural science. A number of John Curtis's very valuable papers on 'Farm Insects', notably on those affecting the turnip crops, were published in the early issues of the Society's Journal; but the contributions on the diseases of the crops were very few and far between, and they contained little that was new. All the scientific enthusiasm in agriculture was going to the other side of the programme: the increase of the fertility of the soil.

In the early forties, the dodge of obtaining 'super* phosphates by treating bones with sulphuric acid was being exploited, supplies of Peruvian guano and Chilean nitrate began to arrive in quantity, and the famous manurial ex- periments at Rothamsted were started by J. B. Lawes (1841). The so-called Chemical Revolution of Lavoisier and his school, which marked the close of the eighteenth century, had led to an illuminating realization of one of the first principles of soil science — really a consequence of the general principle of conservation of mass. The chemists, and notably Justus von Liebig in Germany, had worked out methods of chemical analysis which revealed the amounts of the several elements which various crops took from the soil, and, when this information was available, it was not unreasonable to conclude that the input of the several elements to the soil-bed had to be equal to the out-take for any particular level of productiveness to be maintained. Also, there was reason to suppose that if the soil was enriched with those elements taken by a particular crop, the level of productiveness in respect to that crop could be raised. There were many ways, besides the application of the new imported nitrates and the manufactured 'super* phosphates by which the input and output budget of the elements necessary for plant growth could be raised and balanced at a higher level. The plentiful work which these problems provided, leading as it did to most gratifying and sometimes spectacular increases, was more attractive than the doctor's job of preventing the wastage caused by blights and mildews. A penny saved was never a penny gained, unless the process of saving the penny happened to be as pleasurable, to the human being concerned, as that of gaining it. To dose crops with magical new fertilizers, and then to weigh the produce and determine the gain, was exceedingly good fun, and if, like John Lawes, you happened to have shares in a company selling the fertilizers, there was a good healthy profit motive behind your researches. But the number of people who found delight in the thankless and unremunerative job of wading through all the multilingual prolixities of the cryptogamic botanists, in

8?

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search of information pointing to the rational principles that were to be followed in treating plant diseases — the number of such persons, on earth, was very, very, small.

The outbreak of the Potato Blight in 1845, the famine in Ireland, the spread of the Oidium over the hops and the vines, and the abnormal severity of all the native blights and mildews, during the late forties, provided the grimmest of reminders that the diseases of the crops were not to be neglected. These pestilences were capable of destroying more produce in a couple of bad seasons than could be gained in a decade by the help of the new fertilizers. Indeed, the use of some of these fertilizers, particularly of the imported nitrates, which were then unbalanced by potash, was a disturbing factor, no doubt having something to do with the increase in the prevalence of disease. Excessive nitrogen caused a lush, soft growth of foliage, on which, as it was discovered later, fungal parasites flourished. The total failure to find any remedy for the Potato Blight pointed to the need for some synthesis of the information scattered in the world's scientific literature about plant diseases, and the extraction from it of guiding principles. Knowledge available of one disease might throw light upon another. Berkeley recognized this when he turned back to the half-forgotten work of Prevost, and adduced observa- tions that had been made on the propagation of the Bunt of the wheat, in support of his hypothesis that the Potato Murrain was of fungal origin. But mere searching of the past and contemporary literature was not enough; Berkeley and John Lindley worked hard enough to collect and sift every scrap of information they could find on the Potato Murrain — their writings in The Gardeners9 Chronicle and the Journal of the Horticultural Society were enduring evidence of that — but for the understanding of such plagues which could sweep over the crops of whole continents and make their way from the New World to the Old, or from the Old World to the New, properly organized and far-flung investigations would have to be set up. The job was too big for even the most industrious of professors of botany, or clerical- fungologists, or doctors of medicine on the Continent, to cope with as a mere side-line. Berkeley was indeed writing as a Father of Plant Pathology, when in September 1845 he said: 'There must be a continued series of observations conducted both by practical and scientific men, embracing every possible point and extending to remote districts, with the power of comparing the different phases the disease exhibits and the varying circumstances in which it appears. This alone can lead to anything satisfactory. The expense doubtless would be considerable, but the utility, whether immediate or more remote, would be fully commensurable with the expenditure/

'VEGETABLE PATHOLOGY'

But after the repeal of the Corn Laws — which no more ruined the English farmers than it lowered the cost of bread, since the cost of bringing foreign grain to England made it as expensive as the home-grown — agri- culture was prospering as well as the manufacturing industries. Everybody who had any capital in England was making money hand over fist. Free Trade and a virtual monopoly of machine manufacture was increasing the wealth of the country at such a rate that very much attention to the Blight on the potatoes or the Smut on the corn was hardly to be expected. There was laissez faire for the merchants and the industrialists. There was laissez faire also for the fungi on the crops, and the typhoid in the Poor Law institu- tions. There was laissez faire for the landowners; and the land-enclosure, which was still going on, had reduced the agricultural labourers to pauperism or driven them to the mills. But the progress of appropriation from the powerless had led to vast technical improvements in the practice of English agriculture in the course of a century: the large farms were well-cultivated, and now with better drainage and increasing scientific manuring, agricultural production, like the promotion of railway companies, was pushing ahead.

The English soil was producing three-quarters of the wheat consumed in the country, and keeping pace with the increasing demand. In 1845 die price of wheat was 50s. 9cl. per quarter, in 1847 6ps. 5d., in 1855, 745. pd. (vide Fig. 25, page 145). New sources of wealth were opening up every year. Over the period from 1850 to 1860 a hundred and ten million pounds worth of gold was found in Australia; the Bessemer process cut the cost of steel- making by one half; the first aniline dye was discovered by W. H. Perkin, and the synthetic dye industry began with his factory at Greenford in Middlesex; India was annexed to the Crown, and the bulk of its spinning and weaving industry was appropriated for Lancashire, along with its produce of raw cotton — indeed it was the Golden Age. The English traders were as free as the Thelemites, and, in their own estimation, twice as virtuous.

The grand moral, or amoral, principle behind all this prosperity was Fais ce que vouldras, Free Competition, or Laissez faire. In 1859 it found its poet, not in Matthew Arnold or Macaulay, but in Charles Darwin, for he gave it a new name, 'the survival of the fittest', and proclaimed that it was operative as a natural law from the beginning unto the end of creation. What more was needed to convince those worthy Victorians of the absolute rectitude of their ways? Before Darwin, it was acknowledged with a reluctant piety that the ways of the Almighty might be superior, in certain moral respects, to those of even the most virtuous of men. The Almighty, for example, had a care for every sparrow that fell to the ground. Now that this nonsense was

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exploded, and it was revealed as God's will, or a law of nature, that some smug cat or wily rodent should at once devour the helpless bird, the exploiter of child labour in the mills, or the Irish landlord busy with evictions, need no longer feel bowed in excess of humility before any superior power. On the contrary, he could feel something of the fallen aureole of the Almighty glowing about his ears.

It was not until the fat period was over, and the leaner years of stringent commercial competition with other nations began, that any organized endeavours were made in England to combat the diseases of the crops. After 1847, it was not until 1873, at the beginning of the Great Depression, that the Royal Agricultural Society of England encouraged any further investigation of the Potato Blight. And it was not until years later still, when English agriculture was faced with ruin, that any effective measures to defend the health of the crops were promoted by Government action. By then the lead had passed to other countries; but in plant pathology, as in so many other branches of applied science — instance the synthetic dye industry — it was an English pioneer who made the start which was followed up elsewhere.

In 1854, the Rev. M. J. Berkeley began his famous work on Vegetable Pathology' in The Gardeners9 Chronicle. The idea that there should be a recognized branch of science concerned with the diseases of plants, and to be called 'Vegetable Pathology', as the study of disease in man was called 'Human Pathology', had been simmering in his mind since the publication of his first paper on the Potato Blight in 1846. As nobody seemed inclined to take up the idea, he at last decided to make a start himself, and his Articles, published in serial form, week by week in The Gardeners9 Chronicle, over a period of nearly three years, were the result. His plan was 'to place before his readers, in a compendious and easily accessible form, all that was well ascertained upon the subject. The papers to comprise everything really valuable, both in theory and practice, which could be at all supposed to come within the scope of an intelligent cultivator'.

He began with forty-three Articles on plants in a state of health, and went on systematically to consider what constituted disease in plants, the causes of disease, the classification of diseases, and, lastly, remedial measures. There was one thing about this scheme for which later workers hardly gave him sufficient credit. It had been objected that over the Potato Blight he paid little attention to the general health of the plants, while 'magnifying the fungus seven-hundred-and-eighty diameters'. In the twentieth century, when men of science had outgrown their first enthusiasm for the germ theory of disease, precisely the same objection was raised: the plant

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'VEGETABLE PATHOLOGY'

pathologists were said to pay too much attention to the parasitic fungi and other pathogens, and too little to the conditions necessary for the growth of healthy plants — to the environmental factors of earth, air, light, warmth and moisture. But Berkeley could hardly be said to have neglected these factors, when he devoted forty-three of the Articles to them, before he even began to consider what was meant by disease! His Articles on the nutrition and general physiology of plants in health, were not perhaps the best part of his work, for those were not his subjects, but in putting them first he laid down a good plan for the new science which he sought to define.

When it came to the classification of the abnormalities which he regarded as diseases of plants, Berkeley at first tried to use the same categories which the physicians were then employing for the diseases of man. Internal or constitutional disorders, functional and organic; external or accidental dis- orders, and so on. The limitations of these several categories were exceed- ingly vague, for no two physicians agreed in what they meant by them, and their attempts at definition constituted, for the most part, a scholastic war of words. It was inevitable that this should be so, while the proximate causes of so many diseases were wholly unknown. Berkeley floundered about with 'constitutional' and 'organic* for some while and then his ruling demon took charge. He was a taxonomist, instinctively given to sorting things into genera and species, to which he could assign Latin, or preferably Greek, names. He probably divided all the venial and mortal sins into genera and species on Sunday mornings, and he managed to divide the 'diseases' of plants, on week-days, into forty-two genera, including: Sterilitas, or unpro- ductiveness; Sphrigosis, or rankness; Betchomania, or multiplication of petals; Senectis, or old age; Exostasis, or warts; Heliosis, or sunstroke; and finally Parasitae, or [effects of] external parasites. On all these subjects Berkeley had something interesting to say; his papers contained a wealth of curious and practical information to delight the gardener; his rhetoric was all very philosophical, and rich as Christmas pudding with choice instances of Betchomania or Sphrigosis, but the best of the articles were those on the Parasitae, the relatively few disorders of plants which could then be attributed to vegetable parasites. These articles were the forerunners of the leaflets and monographs on plant diseases which would be issued by every Department or Ministry of Agriculture in the world, half a century later. He gave brief descriptions, intelligible to the gardener, of the fungi which caused the disorders, lingered over the derivation of their names, mentioned the host plants on which each species had been found, paid attention to the weather conditions which seemed to favour their spread, referred to the principal

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experiments which had been made in checking their ravages, discussed the opinions of his contemporaries about them, and freely added any other facts or conjectures which seemed to him pertinent. He went on writing articles on the Parasitae, long after he had brought his 'Vegetable Pathology* to a close, and these addenda contained some of his most valuable contributions. Again and again he put his finger surely on the fungus which was causing a disease, and only the whole history of plant pathology through the nineteenth century would show the great part he had in it. When he came to conclude his scheme of Vegetable Pathology in 1857, with 'Remedial Measures*, he was perhaps getting a little tired, for the articles under this head were few, and not particularly searching.

The Rev. M. J. Berkeley was one of the great Victorians, and he was above all else a worker. A prodigiously hard worker. He was of commanding presence and robust physique. Educated: Rugby and Cambridge. As perpetual curate of Apethorpe and Wood Norton, he had a very small stipend on which to maintain a large family. He was obliged to take in private pupils. He was active in his parochial work. He was a good classical scholar, and he read all the proof-sheets of Bentham and Hooker's Genera Plantarum as linguistic critic. From 1836 to 1870 he was the universal referee for anybody in England who wanted information about fungi. His herbarium of fungi, ultimately acquired by Kew, contained ten thousand species, and the new species he described were not far short of six thousand. In 1857, as though his labours on 'Vegetable Pathology* had not been enough for him, he published his important Introduction to Cryptogamic Botany, a book of six hundred pages, 'with 127 illustrations on wood, drawn by the author*.

In later generations many a mycologist, chancing to look at the portrait in oils of Miles Joseph Berkeley, massive beside his brass microscope, on a wall of the conference room of the Linnean society in London, would be tempted to exclaim: Ah, there indeed was the Father of British Plant Pathology! But saying this they would be somewhat carried away: there never was any such thing as British Plant Pathology, only Plant Pathology, and that was the child of a thousand minds, of the inquiring genius of many nations. Berkeley happened to christen it and give it a name, but it had earlier Fathers in Mathieu Tillet and Fontana, and Benedict Prevost. True, it was a science born of social need, but as necessity was only the mother of invention, and she was there all the time, it was indeed the Fathers of the science that mattered. Some of these men had a real and often conscious desire to serve humanity, to prevent wastage, hunger and suffering. Some loved the growing corn, and the deep enmauved green of potato fields in

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