PART II 



THE ANAEROBIC METABOLISM OF 

 INVERTEBRATES 



CHAPTER I 



PARTIAL TRANSITION FROM AEROBIC TO 

 ANAEROBIC METABOLISM 



A partial transition from aerobic to anaerobic metab- 

 olism seems to occur when the oxygen consumption of an 

 organism declines for one reason or another, and the en- 

 ergy requirements do not decrease in the same propor- 

 tion. The most common cause of a diminished rate of oxy- 

 gen consumption in nature is an abnormally low oxygen 

 concentration in the respiratory medium. 



In our survey of anaerobiosis in invertebrates/ numer- 

 ous instances were cited in which the oxygen consump- 

 tion depended on the tension and it was pointed out that 

 this might imply the presence of fermentative processes 

 at low tensions. A more positive stand was avoided in 

 most cases, because the mere fact of a lowered oxygen 

 intake, without other evidence, does not justify more 

 definite conclusions. It is well to remember that many 

 organisms, such as, worms, crustaceans or insects, be- 

 come motionless in surroundings very poor in oxygen. A 

 cessation, or even a mere decrease of muscular movements 

 will diminish the oxygen needs; the rate of oxidation 

 may therefore simply decrease and the animal may be 

 able to satisfy its reduced energy needs without resorting 

 to anaerobic processes. 



Further evidence of a transition to anaerobic metabo- 

 lism will be obtained if the following points can be 



1. Part 1, Ch. III. 



