ANAEROBIC METABOLISM 207 



glycerol and one molecule of pyruvic acid. This same 

 reaction takes place also as the first step in the decom- 

 position of sugar under aerobic conditions, but it is fol- 

 lowed by the oxidative degradation of the glycerol mole- 

 cule to one molecule of pyruvic acid and water. It is 

 clear that this scheme leaves no room for lactic acid and 

 carbon dioxide. But, in fact, small amounts of both 

 these substances were found, and instead of a theoretical 

 R.Q. of zero, a value of 0.062 was obtained. The ap- 

 pearance of lactic acid and carbon dioxide may, how- 

 ever, not be related to the metabolism of the organisms in 

 question, but may have been due to the metabolism of 

 leucocytes which can hardly be eliminated completely 

 when the trypanosomes are isolated prior to the determi- 

 nations. 



The metabolic processes in Trypanosoma lewisi are 

 quite different. Under anaerobic conditions one mole- 

 cule of glucose is broken down into one molecule of 

 succinic acid and probably one molecule of glycol. 

 The latter is further transformed into acetic acid and 

 ethyl alcohoP, a process in which acetaldehyde is 

 probably an intermediary. It should be noted that this 

 anaerobic glucose decomposition proceeds only if the 

 medium contains bicarbonate (Searle and Reiner, 

 1940, 1941). It appears that under anaerobic conditions 

 carbon dioxide is consumed and that the amount con- 

 sumed (from 0.25 to 1.0 mole per mole of glucose) is 

 about equivalent to the amount of succinic acid produced. 

 Instead of carbon dioxide, pyruvic acid may also influ- 

 ence the anaerobic glucose decomposition ; larger amounts 

 of lactic acid are then formed. It is of interest that the 



1. Trypanosoma leicisi is, according to our present knowledge, the 

 only invertebrate forming ethyl alcohol. It is true that Fieri (1895) 

 described the production of alcohol by anaerobically kept clams. There 

 can be no doubt, however, that in that case, alcohol actually origi- 

 nated from the metabolism of bacteria developing in the water in which 

 he kept his experimental animals. 



