AEROBIC FERMENTATIONS 167 



anaerobic conditions by fermentations alone. He as- 

 sumed, therefore, that the origin of the carbon dioxide 

 must, under either condition, be sought in fermentations, 

 i.e., no carbon dioxide production would be connected 

 with the aerobic processes; these latter would have a 

 respiratory quotient of zero. He sees no reason why 

 parasitic worms kept under aerobic conditions should 

 have higher energy requirements than those kept under 

 anaerobic conditions, and he concludes that the aerobic 

 processes, in these cases, produce no energy. This would, 

 of course, imply that aerobic oxidations in helminths are 

 fundamentally different from those met with in nor- 

 mally aerobic animals; they would resemble rather the 

 processes occurring in the latter during recovery from 

 lack of oxygen. 



More recent investigations, however, have shown that 

 the amount of carbon dioxide excreted by aerobically 

 kept ascarids is greater than that produced under an- 

 aerobic conditions (von Brand, 1934a; Kriiger, 1936 and 

 1937), a fact already observed by Weinland (1901). Fur- 

 ther information is necessary before it can be stated 

 definitely whether this holds true also for trematodes 

 and cestodes. In Ascaris it was shown that the excre- 

 tion of organic acids is more pronounced under com- 

 plete lack of oxygen or under low oxygen tensions than if 

 much oxygen is available (von Brand, 1934a; Krtiger, 

 1936). It has also been definitely established that one 

 of the end products of the aerobic processes is carbon 

 dioxide, and the respiratory quotient was found to be 

 almost unity, instead of zero, as postulated by Harnisch. 

 One is, therefore, forced to conclude that some energy 

 is released by the aerobic processes. 



For what purposes this energy is used is another ques- 

 tion. Harnisch (1937a) still believes that it plays no part 

 in the normal energy supply of these worms, a view some- 

 what similar to that of Kriiger (1937) who thinks that 



