170 AEROBIC FERMENTATIONS 



The situation may become confusing when animals that 

 show the phenomenon of aerobic fermentations are par- 

 tially deprived of oxygen. The excretion of non-oxidized 

 end products will then become accentuated. This hap- 

 pens, for example, in Ascari^ (Kriiger, 1936). It is then, 

 however, not possible to tell w^hat portion of the end 

 products is due to processes induced by local oxygen de- 

 ficiencies of certain cells or tissues and what portion to 

 aerobic fermentations since in this worm the end prod- 

 ucts of both processes are identical. In animals like the 

 trypanosomes in which the end products of the two proc- 

 esses are at least partially different, a distinction would 

 probably be possible even at low oxygen tensions. But, 

 so far, experiments have been carried out with these 

 animals only under fully aerobic conditions and under 

 complete lack of oxygen, not with intermediate, low oxy- 

 gen tensions. 



