ANAEROBIC METABOLISM 217 



ever, had calculated, by comparing the heat of combus- 

 tion of entire worms with that of the glycogen content 

 of fresh and of starving animals, that carbohydrate fer- 

 mentations furnish only about 80 per cent of the total 

 energy. Von Brand and Jahn {I.e.) remark that at the 

 present state of our knowledge any calculation of the 

 energj^ yield would be only approximate ; their tentative 

 estimate lies between 6 and 12 per cent. 



Among cestodes, the mixed fermentations of only one 

 species, Moniezia expansu, have been studied in some de- 

 tail (von Brand, 1929, 1933a; Alt and Tischer, 1931). This 

 worm produces daily, during its anaerobic metabolism, 

 0.44 g. carbon dioxide, 0.20 g. higher fatty acids, 0.16 g. 

 lactic acid and 0.04 g. succinic acid. These acids ac- 

 count for 79 per cent of the total acidity of the saline 

 medium determined by titration. The non-identified 

 fraction may well consist of oxalic acid, which, according 

 to Loeper and Tonnet (1931), accumulates within the 

 body of an unspecified (human?) Taenia species, reach- 

 ing 0.138 per cent of the weight of the animal during a 

 24-hour experimental period. 



Arthropods. Only one case of mixed carbohy- 

 drate fermentation has been described in arthropods. Von 

 Kemnitz (1916) observed that, under anaerobic condi- 

 tions, 100 g. of larval material of GasteropMlus intesii- 

 nalis form 0.060 g. fat from glycogen, and liberate 0.276 

 g. carbon dioxide in 24 hours {cf. also Weinland, 1915). 

 Since in the same period 0.723 g. glycogen are consumed, 

 it is quite obvious that other substances must also have 

 been formed. One of these is lactic acid, the formation 

 of which has been proved definitely by Dinulescu (1932) 

 and Blanchard and Dinulescu (1932) ; but the amounts 

 found by these authors are hardly large enough to ex- 

 plain the discrepancy between the loss of glycogen and 

 the sum of the end products identified. Von Brand ( 1934) 

 points out that the only question studied so far is how 



