22 MKTU()D>i OF jyVE^TKiATIOX 



it has been concluded, even hy quite recent investigators, 

 that an animal forms lactic acid when carbon dioxide is 

 liberated. Such a conclusion is in many cases erroneous. 

 The liberation of carbon dioxide from bicarbonate indi- 

 cates only that an acid stronger than carbonic acid has 

 been formed. The misunderstanding arises from the fact 

 that many investigators simply generalize, applying to 

 all tissues what happens in mammalian tissues. It is 

 true that in the latter lactic acid is the only, or at least 

 by far the most important, organic acid formed. In 

 many invertebrates, however, lower or higher fatty acids, 

 dibasic acids and others are formed instead of or in ad- 

 dition to lactic acid during the anaerobic carbohydrate 

 metabolism, A chemical identification is therefore abso- 

 lutely necessary if one washes to make any specific state- 

 ment as to the nature of the acids formed. 



