CHAPTER III 



THE ORIGIN OF ANAEROBIOSIS IN 

 INVERTEBRATES 



The idea that, in jihylogenetic development, the anaero- 

 bic type of life preceded the aerobic has been expressed 

 repeatedly (Piitter, 1905; Snyder, 1911; Clark, 1924; 

 Kollath, 1935; Koschtojanz, 1935a; Szent-Gyorgy, 1939), 

 but it seems not to have received much attention from 

 biologists and physiologists. Those who discussed it 

 were, in general, not inclined to accept it. Krogh (1916), 

 for example, who is a recognized authority on respira- 

 tion, designated the view that the anaerobic metabolism 

 is more primitive than the aerobic as a '' singular propo- 

 sition" although he conceded that it "probably con- 

 tains an element of truth, in so far as the initial stage in 

 the breakdown of the foodstuffs is probably not oxida- 

 tive." Jordan (1934) rejects the idea because the elim- 

 ination of the end products of the anaerobic metabolism 

 seems to require special mechanisms ; and from this stand- 

 point the anaerobic metabolism cannot be more primi- 

 tive than the aerobic. 



Snyder {I.e.), the most ardent proponent of the phylo- 

 genetic precedence of anaerobiosis, formulates the chief 

 evidence as follows : 



"1. What appear to be the simplest forms of life are 

 anaerobic still and the majority of lower organisms, both 

 plant and animal, can . live under anaerobic conditions 

 more or less continuously. 



"2. The fundamental chemical processes of the cell 

 in all organisms, even the highest, are anaerobic, phe- 

 nomena of oxidation being of secondary or ulterior im- 

 portance. 



"3. The relations of anaerobic and aerobic life are 

 genetic and we have clear evidence of the gradual evo- 

 lution of the latter from the former, an increasing need 



