276 



PHYSIOLOGY OF THE FUNGI 



^ ^ 



r^HI 



sterilization 



Cone. 



Cotton wool 



mh: 



Fig. 53. Apparatus for studying the metabolic products of fungi and other micro- 

 organisms. The apparatus consists of five units: A gasholder, P; a train for the puri- 

 fication and sterilization of air or other gases, A-E\ the culture flask, F; a train for the 

 quantitative absorption of carbon dioxide, H-M; an aspirator, Q, for the collection 

 of gaseous products of metabolism other than carbon dioxide. (Redrawn from Birkin- 

 shaw and Raistrick, Trans. Roy. Soc. (London), Ser. B, 220: 14, 1931. Published by 

 permission of the Royal Society.) 



is the supply of oxygen. The relation between fermentation and anaero- 

 bic conditions was recognized by Pasteur, who summarized his extensive 

 investigations on fermentation as "la vie sans air." The essential feature 

 of fermentation is anaerobic dissimilation of carbohydrates. Growth and 

 fermentation are competitive processes, for fungi require oxygen for 

 growth. In practice it is advantageous to carry out fermentations in the 



