SUM3IARY 255 



Aitarrobic processes. 



1. Tlie anaerobic processes liberating energy from car- 

 bolij'drates are more varied in invertebrates than in ver- 

 tebrates. Lactic acid fermentation occurs in both groups, 

 but well authenticated cases of fatty acid fermentations 

 and of mixed fermentations (with lactic acid, fatty acids, 

 dibasic acids or even occasionally alcohol as end prod- 

 ucts) are recorded only for invertebrates. In some cases 

 the fatty acids (higher and lower) are the only organic 

 end products, though it is possible that lactic acid is 

 formed as an intermediate substance. 



2. No reaction in which fatty acids are attacked under 

 anaerobic conditions is known to occur in invertebrates ; 

 but glycerol may serve as a substrate for anaerobic me- 

 tabolism. 



3. Little is known on anaerobic protein degradation. 

 Ammonia is the most commonly formed end product. 



4. Carbon dioxide is found in practically all experi- 

 ments with auaerobically kept invertebrates. It may 

 originate directly from the breakdown of organic food 

 material, or it may be set free from inorganic substances 

 under the action of acids. 



5. Combustible gases, especially hydrogen, are formed 

 occasionally during anaerobiosis ; the best-known cases 

 have been reported among parasitic protozoa. 



6. The few available data on anaerobic enzymes in in- 

 vertebrates are too few to allow one to make any general 

 statement as to their action. 



Recovery from anaerobiosis. 



1. Many invertebrates which become paralyzed when 

 deprived of oxygen revive when brought back to aerated 

 surroundings. The time required for the resumption of 

 movement depends on the species and also on the length 

 of the preceding anaerobic period. 



