58 Synopsis of the Bacteria and Yeast Fungi. 



surround themselves each with a membrane, and so pro- 

 duce the spores, which can bud like the vegetative cells. 



To the Yeast Fungi (in the narrower sense) belongs the 

 capacity of decomposing the sugar of a fluid into alcohol 

 and carbonic acid, i.e. of exciting alcoholic fermentation. 



The carbonic acid comes off in rapid streams of bubbles, 

 while the alcohol, as well as certain subordinate constituents 

 of sugar, remains behind. 



The fermentation proceeds most energetically with re- 

 stricted access of air ; but, if the air is excluded for a long 

 time, the yeast cells perish. 



The same is true of the Saccharomycetes, especially in 

 a botanical aspect, as of the Schizomycetes. Just as in 

 the latter case, so also in this, it is necessary to impose 

 a limit upon the accepted species, and only those founded 

 by trustworthy investigators can be considered. Of course 

 there remain even then many doubtful points for the ma- 

 jority of the now accepted species of Saccharomycetes may 

 be only various forms of one and the same species, which 

 have become differentiated by changed conditions of growth. 



XVII. SACCHAROMYCES, Meyen (in Wiegmann's 

 Archiv, iv. vol. ii. p. 100). 



Unicellular Fungi, with vegetative increase by budding, 

 and reproduction by spores, which, for the most part, arise 

 by subdivision of the contents of the mother-cell. 



A. SPECIES NOT PRODUCING A MYCELIUM. 



80. S. cerevisiae, Meyen (I.e.}. 

 Torula cerevisice, Turpin. 

 Cryptococcus fermentum, Kiitzing. 

 Cryptococcus cerevisia, Kiitzing. 



