214 ANAEROBIC METABOLISM 



ed and the phosphoric acid liberated suffice to account 

 for the total acidity obtained (Fischer, 1924). 



From this observation Fischer postulates that carbo- 

 hydrate decomposition proceeds along identical lines in 

 the worm and in vertebrates; in other words, he does 

 not believe that fatty acids are a normal end product of 

 invertebrate anaerobic metabolism. But, as von Brand 

 and Jahu (1942) point out, Fischer's observation may 

 merely indicate that the chemical processes are not iden- 

 tical in minced material and in intact animals ; they draw 

 attention to the well-established fact that in yeast and 

 other lower plants different metabolic end products may 

 be found depending upon the conditions under which the 

 experiments are conducted. 



Another criticism against the assumption of fatty acids 

 as end products of anaerobic carbohydrate metabolism 

 was brought forward by Slater (1925). He found, in a 

 saline solution in which ascarids had been kept, bacte- 

 ria which, upon being cultivated in nutritive media, were 

 capable of transforming sugar into volatile fatty acids. 

 He assumed that such bacteria were responsible for the 

 appearance of valeric and other fatty acids in the experi- 

 ments of other authors. Slater, however, did not show 

 that these bacteria develop in large numbers in the non- 

 nutritive saline solutions commonly used in experiments 

 with worms and did not investigate whether the postu- 

 lated single end product, lactic acid, is a good substratum 

 for the biological activity of the bacteria. 



A few years later the same author, in his review on 

 anaerobic life (Slater, 1928), developed more fully the 

 idea that lactic acid is the only end product resulting 

 from an anaerobic carbohydrate breakdown, both in ver- 

 tebrates and in invertebrates. This conviction of his is 

 quite clearly the reason why he rejects the experiments 

 of his predecessors. But good reasons can be adduced to 

 show that the fatty acids are produced by the animals 



