192 SOURCES OF ENERGY IN ANAER0BI08IS 



digest cellulose; others (Braune, 1914; Schulze, 1924, 

 1927 ; Trier, 1926 ; Weineck, 1934) maintain that they do. 

 The truth seems to be that different species behave dif- 

 ferently. Hungate (1942, 1943) demonstrated conclu- 

 sively that all Diplodinium species utilize cellulose; 

 while Entodinium, Isotricha, Dasytricha and Biitschlia do 

 not. Tests designed to prove the presence of a cellulase 

 were positive in the case of Diplodinium maggii. 



(d) VARIOUS POLYSACCHARIDES AND SUGAR-ALCOHOLS. 



Dextrin and inulin are used by some protozoa in their 

 aerobic fermentative reactions in the presence of oxygen 

 (Table 21) and seem to represent, at least in some cases, 

 valuable mother-substances for these processes. Sugar- 

 abohols have been little studied and seem to be used for 

 fermentations by only a few protozoa (Table 21). It would 

 be of great interest to investigate whether snails kept in 

 the absence of air are capable of metabolizing galactogen. 

 Young eggs of Helix would be an especially suitable ma- 

 terial, since they store large amounts of this polysaccha- 

 ride and no glycogen (May, 1932). 



2. FATS 



The evidence that invertebrates are capable of utilizing 

 fat under anaerobic conditions is rather meager. 



Brault and Loeper (1904b) described a decrease in the 

 number of microscopically visible fat globules in the 

 oocysts of Eimeria stiedae in their normal habitat (en- 

 larged bile ducts of rabbits) which is very poor in oxygen. 

 The observations of these authors, however, do not carry 

 much weight because of the unreliability of staining 

 methods. It is a well-known fact that the disappearance 

 of morphologically demonstrable fat globules does not 

 necessarily indicate that some of the fat has actually 

 been used up. The same criticism applies to Dyrdow- 

 ska's (1931) statement that considerable amounts of 

 lipids which can be demonstrated with the help of dyes 



