836 REPORT— 1897. 



In all these cases the same principal f'acts come out — a saccharine 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 1860, 

 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 in 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 morphological 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 Saccharomyces to the fungus, showing that several species or forms existed, 

 some of which develop definite spores. 



In 1883, Hansen, of Copenhagen, taking advantage of the strict methods of 

 culture introduced and improved by De Bary, Brefeld, Klebs, and other botanists, 

 had shown that by cultivating yeast on solid media from a single spore it was 

 possible to obtain constant types of pure yeasts, each with its own peculiar 

 properties. 



One consequence of Hansen's labours was that it now became possible for 

 every brewer to work with a yeast of uniform type instead of with haphazard 

 mixtures, in which serious disease forms might predominate and injure the beer. 

 Another consequence soon appeared in Hansen's accurate diagnosis of the specific 

 or varietal characters of each form of yeast, and among other things he showed 

 that a true yeast may have a mycelial stage of development. The question of the 

 nucleus of the yeast-cell, on which Mr. Wager will enhghten us, has also occupied 

 much attention, as have also the details of spore formation. 



Meanwhile, a question of very general theoretical interest had arisen. 



Reess, Zopf, and Brefeld had shown that many higher fungi can assume a 

 yeast-like stage of development if submerged in fiuids. Various species of Mticor, 

 ^Ustilago, Exoascus, and as we now know, numerous Ascomycetes and Basidio- 

 mycetes as well, can form budding cells, and it was natural to conclude that 

 -probably the yeasts of alcoholic fermentation are merely reduced forms of these 

 higher fungi, which have become habituated to the budding condition — a con- 

 ■clusion apparently supported by Hansen's own discovery that a true ISaccharornyces 

 can develop a feeble but unmistakable mycelium. 



With many ups and downs this question has been debated, but as yet we do 

 not know that the yeasts of alcoholic fermentations can be developed from higher 

 fungi. 



During the last two years it appeared as if the question would be settled. 

 Takamine stated that the Aspergillus used by the Japanese in brewing sak6 from 

 rice develops yeast-hke cells which ferment the sugar derived from the rice. 

 Jiihler and Jorgensen then extended these researches and claimed to have found 

 yeast-cells on other forms of fungi on the surface of fruits, and to have 

 established that they develop endogenous spores — an indispensable character in 

 the modern definition of the genus Saccharomyces — and cause alcoholic fermen- 

 tation. 



Klocker and Schionning have this last year published the results of their very 

 ingenious and thorough experimental inquiry into this question, and find, partly 

 by pure cultures of the separate forms, and partly by means of excellently devised 



