516 BIOLOGY OF THE MICRO-ORGANISMS. 



b. Conditions of Life of the Budding Fungi. 

 1. Chemical Composition of the Budding Fungi. 



- ^ S re & ar ds the budding fungi, very numerous experi- 

 cai compost- ments have been made, which enable us to obtain a 

 fairly accurate idea of their chemical composition and of 

 their tissue change. These experiments have almost 

 entirely been limited to the ordinary yeast of beer, 

 which on account of its value in the preparation of food 

 has always excited special interest. It is seldom that 

 other species of these fungi, such as Mycoderma vini 

 (A. Schultze, in Mayer's Chemistry of Fermentation], 

 have been chosen for investigation. 



Complete analyses of yeast have been published by 

 the following authors : Schlossberger, Mulder and 

 Wagner, Mitscherlich, Pay en, Liebig.* The following 

 was the average result in washed and dried yeast, 

 freed as much as possible from ashes : 



48 per cent. C, 9 12 per cent. N, 6 7 per cent. 

 H, 0*6 per cent. S. 



More recent analyses by Niigelif have led to the 

 following results in the case of yeast used for low 

 fermentation : 



Cellulose and mucous material of cell wall 37 per cent. 



Albuminous materials 45 



Peptone 2 , 



Fat 5 



Extractives (glycerine, leucine, &c.) ... 4 , 



Ashes ... ... ... ... ... ... 7 



. Yeast which has been carrying on fermentation for a 

 considerable time contains, according to Pasteur and 

 others, a markedly less amount of nitrogen (only 5*0 to 

 5*5 per cent.) . Schlossberger and Mulder have attempted 

 to isolate the albuminoid materials, either by treatment 

 with potash lye or with acetic acid ; and they made out 

 that the isolated materials had a composition closely 



* See Mayer, Lehrbuch der Giihrungschemie, 1879, p. 110. Shiitzen- 

 berger, Gdkrungserscheimmgen, p. 58. 



f Sitzunysber. d. bayr, Acad. d. Wiss. 1878, May. 



