ALCOHOLIC FERMENTS. 223 



10-30 C.; optimum, 28 C. Film-formation at 4-31 C.; very 

 slow and weak. " Eesting " cells very abundant in the 

 film. 



Type 7 possesses oval cells, often approximating to a 

 spherical shape ; " gigantic cells " regularly occur, and rich 

 formation of chains of small oval cells at the end of fermenta- 

 tion. The young colonies on gelatine are irregular, sinuous 

 and fringed. This variety does not readily develop spores. 

 Spore-formation at 13-30 C. ; optimum, 25-26 C. Film- 

 formation at 4-28 C.; begins sooner than in the other varieties. 

 Few " resting cells " in the film. 



A series of ellipsoidal wine-yeast species were characterised 

 morphologically and biologically by ADERHOLD. KAYSER also 

 described a considerable number of wine-yeasts from different 

 countries, as well as the various species occurring in cider- 

 fermentation. 



By way of examples illustrative of the considerable differ- 

 ences which may occur among high-fermentation culture-yeasts, 

 may be mentioned the following nine species of JEnglish high- 

 fermentation yeast, which were prepared in a state of absolute 

 purity in the author's laboratory, and described by him in 

 conjunction with J. CH. HOLM : 



The two morphological and biological stages the alcoholic 

 fermentation and the film- or mould-stage were pictured and 

 described from growths developed in the following manner : 



The alcoholic fermentation stage from growths which had 

 first been kept for a considerable length of time in a 10 per 

 cent, saccharose solution, then cultivated during several 

 generations in brewery- wort, and finally developed in the same 

 liquid in Pasteur flasks for 24 hours at a temperature of 

 25 C. 



The development of the films and their appearance to the 

 naked eye were studied by means of growths in brewery-wort 

 in Erlenmayer flasks at the room temperature (about 20C.). 



The cell-forms of the films were observed by means of 

 growths in Pasteur flasks at 20 C. after five months' culture. 



The condition of the deposited yeast was estimated by 

 growths in Pasteur flasks at the room-temperature. 



The fermentation experiments were conducted at room- 



