SOURCES OF ENERGY IX AXAEROBIOSTS 191 



brate, fasilitates the development of intestinal protozoa 

 (cf. Mowry and Becker, 1930; Sassuchin, 1931; Hegner 

 and Eskridge, 1937; Armer, 1944). Armer is the first 

 to have attempted to explain this phenomenon on the 

 assumption that the parasites then have access to suit- 

 able mother-substances for an anaerobic carbohydrate 

 metabolism. 



One may expect that starch — or more likely its degra- 

 dation produ3ts — will also favor the development of many 

 metazoan parasites that normally lead a predominantly 

 anaerobic existence. Yon Brand (1933a), showed that 

 the glycogen content of the dog tapeworm. Taenia hyda- 

 tigena, is higher when the host receives a diet high in 

 carbohydrates than if it is kept on a normal diet. Chand- 

 ler (1943a) found that the growth of Hymenolepis dimi- 

 nuta is markedly inhibited if the host (chicken) is kept 

 on a carbohydrate-free diet. 



It should finally be emphasized that soluble starch is 

 quite a good mother-substance for the fermentative 

 metabolism of various protozoa in aerobic conditions {cf. 

 Table 21). 



(c) CELLULOSE. Ingested cellulose is the substrate for 

 anaerobiosis in two groups of protozoa, the intestinal 

 parasites of termites and of the roach Cryptocercus punc- 

 tulatus, and some ciliates which live in the stomach of 

 ruminants. It will be recalled that these organisms 

 thrive only in surroundings that are largely anaerobic. 



It is a well-established fact that many termite protozoa 

 ingest particles of wood ( Cleveland, 1924, 1925a ; Swez}^ 

 1923) and that they digest it by means of a cellulase and 

 cellobiase (Trager, 1932; Cleveland, Hall, Sanders and 

 Collier, 1934; Hungate, 1938, 1943a). 



The question w^hether cellulose plays a role in the nu- 

 trition of rumen ciliates has long been a controversial 

 one. Some investigators (Dogiel, 1925; Margolin, 1930; 

 Usuelli, 1930; Westphal, 1934) doubt that these animals 



