ANAEROBIC METABOLISM 213 



agree that rather large amounts of carbon dioxide are 

 produced; most of them also maintain that lower fatty 

 acids are the most characteristic constituents of the ex- 

 creta. Weinland was the first to recognize that valeric 

 acid is the predominant one, but he found, in addition, 

 some caproic acid. To these must be added small amounts 

 of formic and butyric acids (Flury), perhaps propionic 

 acid (Toryu), and acetic acid, as well as some unidenti- 

 fied higher acids (Oesterlin). "Which of the isomers of 

 valeric acid occurs is not certain ; it is probably the nor- 

 mal acid (Waechter), although Flury suggested that it 

 might be iso-valeric acid, and Krtiger thought he had 

 identified methyl-ethyl-acetic acid. No intermediate 

 products have so far been isolated and the exact manner 

 of the formation of the valeric acid is therefore not 

 kno^\m. Weinland (1901) proposed the following equa- 

 tion : 



4 CeHisOe— >9 CO2+3 C5H10O2 + 9 H2 



But this equation is hardly satisfactory since no hydro- 

 gen is liberated. Koenigs {cf. Weinland, 1901) proposed 

 the equation: 



13 C6H12O6— 12 C5H10O2 + I8 CO2 + I8 H2O 

 which Weinland rejected because the amount of carbon 

 dioxide actually produced was considerably higher than 

 should be expected. One can, however, assume that the 

 excess carbon dioxide originates from bicarbonate or 

 from the breakdown of proteins. Jost (1928) suggested 

 that the intermediate steps in Koenig's reaction are the 

 formation of lactic, pyruvic, propionic and gamma-hy- 

 droxyvaleric acids. The connection thus suggested be- 

 tween the formation of lactic acid and that of fatty acids 

 deserves consideration since small amounts of lactic acid 

 were found amongst the excreta of Ascaris and Paras- 

 caris (von Brand, 1934a; Toryu, 1936). It has even been 

 demonstrated that if minced material of Parascaris is 

 employed instead of intact animals, the lactic acid form- 



