September 9, 1897] 



NATURE 



457 



emanations of diseased states, and that " spontaneous genera- 

 tion" was a hydra not yet destroyed, we obtain some notion of 

 the condition of this subject about i860. 



As with other groups of plants, so with the Fungi, the first 

 studies were those of collecting, naming and classifying, and 

 prior to 1850 the few botanists who concerned themselves with 

 these cryptogams at all were systematists. So far as the larger 

 fungi are concerned, the classification attained a high degree of 

 perfection from the point of view of an orderly arrangement of 

 natural objects, and the student of to day may well look back 

 at the keen observation and terse, vivid descriptions of these 

 older naturalists, which stands in sharp contrast to much of the 

 more slovenly and hurried descriptive work which followed. 



It may be remembered that even now we rely mainly on the 

 descriptions and system of Fries {1821-1849) for our grouping 

 of the forms alone considered as fungi by most people, and 

 indeed we may regard him as having done for fungi what 

 Linnaeus did for flowering plants. 



But, as you are aware, a large proportion of the Fungi are 

 microscopic, and in spite of the conscientious and beautiful work 

 of several earlier observers, among whom Corda stands pre- 

 eminent, the classification and descriptions of the thousands of 

 forms were rapidly bringing the subject into chaos. 



The dawn of a new era in Mycology was preparing, however. 

 A few isolated observers had already begun the study of the 

 development of Fungi, but their work was neglected, till Persoon 

 and Ehrenberg at the beginning of this century again brought 

 the subject into prominence, and then came a series of dis- 

 coveries destined to stimulate work in quite other directions. 



The Tulasnes may be said to have brought the old period to 

 a close, and prepared the way for the new one ; they combined 

 the powers of accurate observation with a marvellous faculty of 

 delineation, and applied the anatomical method to the study of 

 fungi with more success than ever before. Their new departure, 

 however, is more evident in their selection of the parasitic fungi 

 for study, and you all know how indispensable we still find their 

 drawings of the germinating spores of the Smuts and Rusts. It 

 is difficult to say which of their works is the most masterly, but 

 probably the study of the life-history of Claviceps purpurea de- 

 serves first place, though successive memoirs on the Uredinese, 

 Ustilaginea;, Peronosporeae, Tuberacere, and then that magni- 

 ficent work, the " Selecta Fungorum Carpologia," cannot be 

 forgotten. 



In England, Berkeley was the man to link the period previous 

 to i860 with the present epoch. A systematist and observer of 

 high power, and with a rare faculty for appreciating the labours 

 of others, this grand old naturalist did work of unequalled value 

 for the period, and the student who wishes to learn what was 

 the state of mycology about this time will find it nowhere better 

 presented than in Berkeley's works, one of which — his " Intro- 

 duction to Cryptogamic Botany" — is a classic. 



Like all classifications in botany, however, that of the fungi 

 now took two courses : one in the hands of those who collated 

 names and herbarium-specimens, and proposed cut and dried, but 

 necessary and from a certain point of view very complete 

 systems of classification, and those who, generalising from 

 actual cultures and observation of the living plant, proposed 

 outline schemes, the details of which should be filled in by their 

 successors. 



No one who knows the history of botany during this century 

 will deny that it is to the genius of De Bary that we owe the 

 foundation of modern mycology, for it was this young Alsatian 

 who, though profoundly influenced by the work of Von Mohl 

 and Schleiden on the one hand, and of Unger and the Tulasnes 

 on the other, refused to follow either the school of the phyto- 

 tomists — though his laborious " Comparative Anatomy of the 

 Ferns and Phanerogams" shows how well equipped he was to 

 be a leader in that direction — or that of the anatomical mycol- 

 ogists. No doubt the influence of Cohn, Pringsheim, and others 

 of that new army of microscopists who were teaching the neces- 

 sity of continued observation of living organisms under the 

 microscope, can be traced in impelling De Bary to abandon the 

 older methods ; but his own unquestionable originality of 

 thought and method came out very early in his investigations on 

 the Lower Algae and Fungi. If I may compare a branch of 

 science to an arm of the sea, we may look on De Bary's in- 

 fluence as that of a Triton rising to a surface but little disturbed 

 by currents and eddies. The sudden upheaval of his genius set 

 that sea rolling in huge waves, the play of which is not yet 

 exhausted. 



NO. 1454, VOL. 56] 



The birth and flow of the new ideas, expressed in far-reach- 

 ing generalisations and suggestions which are still moving, led 

 to the revolutions in our notions of polymorphism, parasitism, 

 and the real nature of infection and epidemics. His develop- 

 ment of the meaning of sexuality in Fungi, his startling dis- 

 covery of heteroecism, his clear exposition of .symbiosis, and 

 even his cautious and almost wondering whisper of chemotaxis 

 were all fruitful, and although the questions of enzyme-action 

 and fermentation were not made peculiarly his own, he saw the 

 significance of these and many other phenomena now grown so 

 important, and here, as elsewhere, thought clearly and boldly, 

 and criticised fearlessly with full knowledge and justice. 



I do not propose to occupy our time with even a sketch of the 

 history of these and other ideas of this great botanist ; but 

 rather pass to the consideration of a few of the results of 

 some of them in the hands of later workers, in schools now far 

 developed and widely independent of one another, but all 

 deeply indebted to the genial little man whom we so loved and 

 revered. 



The most marked feature noticed in the founding of the new 

 schemes of classification of the Fungi was the influence of the 

 results of pure and continuous cultures introduced by De Bary. 

 The effect on those who followed can best be traced by examining 

 the great systems of subsequent workers, led by Brefeld and Van 

 Tieghem, and the writings of our modern systematists. This 

 task is beyond my present scheme, however, and there is only 

 time to remind you of the fungus floras of Saccardo, Constantin, 

 Massee, and others, in this connection. 



The word " fermentation " usually recalls the ordinary pro- 

 cesses concerned in the brewing of beer and the making of wines 

 and spirits ; but we must not forget that the word connotes all 

 decompositions or alterations in the composition of organic sub- 

 stances induced by the life-activities of Fungi, and that it is a 

 mere accident which brings alcoholic fermentation especially into 

 prominence. 



I ventured some time ago to term alcoholic fermentation the 

 oldest form of microscopic gardening practised by man, and this 

 seems justified by what we know of the very various and very 

 ancient processes in this connection. 



But the making of beers, wines, and spirits, as we understand 

 them, constitutes but a small part of the province of fermenta- 

 tion, and even when we have added cider and perry, ginger- 

 beer, and the various herb and spruce beers to the list, we have 

 by no means exhausted the tale of fermented drinks. Palm-wines 

 of various kinds, toddy, pulque, arrack, kava, and a number of 

 tropical alcoholic fermented liquors have to be included, and the 

 koumiss and kephir of the Caucasus, the curious Russian kwass, 

 the Japanese sake, and allied rice-preparations must be men- 

 tioned, to say nothing of the now almost forgotten birch-beer, 

 mead and metheglin, and various other strange fermented 

 decoctions of our forefathers' time, or confined to out-of-the-way 

 localities. 



In all these cases the same principal facts come out— a sac- 

 charine liquid is exposed to the destructive action of fungi, which 

 decompose it, and we drink the altered or fermented liquor. As 

 is now well known, the principal agents in these fermentations 

 are certain lower forms of fungi called yeasts, and since Leeuwen- 

 hoeck, of Delft, discovered the yeast cells two hundred years ago, 

 and La Tour, Schwann, and Kiitzing (about 1840) recognised 

 them as budding plants, living on the sugar of the liquid, and 

 which must be classed as Fungi, the way was paved for two 

 totally different inquiries concerning yeast. 



One of these was the fruitful one instigated by Pasteur's genius 

 about i860, and concerned the functions of yeast in fermentation. 

 In the hands of Naegeli, Brefeld, and others abroad, and of 

 A. J. and Horace Brown and Morris and others in England, 

 Pasteur's line of research was rapidly developed, and, as we all 

 know, has had a wide influence m stimulating investigation and 

 in suggesting new ideas ; and although the theory of alcoholic 

 fermentation itself has not withstood all the criticism brought 

 against it, and seems destined to receive its severest blow this 

 year by E. Buchner's isolation of the alcoholic enzyme, we must 

 always honour the school which nursed it. 



The divergent line of inquiry turned on the origin and mor- 

 phological nature of yeast. What kind of a fungus is yeast, and 

 how many kinds or species of yeasts are there ? 



Reess, in 1870, showed the first steps on this long path of 

 inquiry, and gave the name Saccharoviyces to the fungus, show- 

 ing that several species or forms existed, some of which develop 

 definite spores. 



