218 1 A 1 1' /^'o liic 1/ !■: T. 1 />' J J I .s'.i/ 



much lactic acid and fat accumulate within the body of 

 the larvae; the possibility that some of the end products 

 of anaerobic metabolism, perhaps lactic acid, may be ex- 

 creted would also deserve attention. 



2. FATS 



We will consider here only fats proper since nothing 

 whatever is known as to whether lipoids like cholesterol, 

 phosphatids, etc., are capable of furnishing energy un- 

 der anoxic conditions. It may be noticed, in connection 

 with this problem, that in a number of parasites which 

 live in nearly anaerobic habitats, large amounts of un- 

 saponifiable ether-soluble materials have been found (c/., 

 for Goussia gadi: Panzer, 1911 and 1913; for Ascaris: 

 Flury, 1912; Faure-Fremiet, 1913; Schulz and Becker, 

 1933; for Fasciola: von Brand, 1928; for Moniezia: von 

 Brand, 1933a; for MacracanthorhyncJius: von Brand, 

 1939). 



A fat, as this term is used here, is a compound of 

 fatty acids and glycerol. A fatty acid has only two oxy- 

 gen atoms in its molecule and these two atoms are al- 

 ready combined with the end-carbon. Shifting processes 

 similar to those mentioned above for carbohydrates are 

 consequently not possible. A fatty acid molecule might, 

 however, split into a hydrocarbon and carbon dioxide. A 

 somewhat similar mechanism is assumed by Weinland 

 (1906) to occur in minced material from pupae of Calli- 

 phora vomitoria. He found that the disappearance of fat 

 under anaerobic conditions was accompanied by the pro- 

 duction of carbon dioxide and hydrogen. These gases 

 appeared in the proportion of 2 to 1. Weinland is of the 

 opinion that they originated, at least in large part, from 

 a decomposition of the carboxyl group of the fatty acid 

 molecule, according to the formula : 



C15H31COOH— C15H31+CO2+H 

 But such a reaction would leave one unsaturated link- 

 age on the last carbon atom of the radical ; one would have 



