186 MICRO-ORGANISMS AND FERMENTATION. 



In a distinct group vegetative propagation takes place only 

 by division through transverse walls. 



In most species the germinating spores grow into budding 

 cells ; in some the spore puts out a germinating thread. 



The Saccharomyces cells in one and the same species occur 

 in different forms. 



In the cells nuclei are present, but they can only be observed, 

 as a rule, after special treatment. 



The cells secrete a gelatinous net-work, which under favour- 

 able conditions may develop freely. 



The greater number of the species induce alcoholic fer- 

 mentation. 



As was remarked above, the names Sacch. cerevisice, ellip- 

 soideus, Pastorianus, etc., are now used in a sense widely 

 different from that originally attached to them by BEESS. 

 HANSEN'S work clearly showed that the distinctive characters 

 of the species cannot, as supposed by EEESS, be foretold by the 

 size and shape of the cells in themselves. A species which 

 under certain conditions may occur in forms, denoted by 

 REESS as Saccharomyces cerevisice, i.e., with large oval cells, may, 

 under other conditions, develop a growth which according to 

 REESS is to be described as Sacch. ellipsoideus, and, conversely, 

 the same species which under certain circumstances are to be 

 described as S. cerevisice or S. ellipsoideus must under other 

 conditions be designated as S. Pastorianus. Thus, shape and 

 size of the cells can only be used as distinctive characters of 

 the species if, in conjunction, it is stated under what particular 

 conditions of cultivation the growth has developed. As, how- 

 ever, under identical conditions of growth there are a large 

 number of species which, according to the shape of the cells, 

 would all have to be described as Sacch. ellipsoideus, Sacch. 

 cerevisice, etc., it follows that REESS'S names, if used in the 

 sense under discussion, would form the names of groups of 



upon a budding-fungus stage. Similar phenomena were previously observed 

 by BAIL, DE BARY, REESS, ZOPF, and others. As BREFELU did not show 

 whether these forms possess the power of endogenous spore-formation charac- 

 teristic of Saccharomycetes, nor whether they are able to display any marked 

 fermentative activity, his assertions that they are equivalent to Saccharo^ 

 mycetes are destitute of foundation. 



