94 PLANT RESPIRATION 



only if the stimulated objects respire alternately" under aerobic 

 and anaerobic conditions. If the experimental material is 

 left without oxygen, wound stimulation has no effect on the 

 anaerobic respiration. 



It must be pointed out at once that the genetic connection 

 of anaerobic with normal respiration is not fully proven by 

 the facts just given. A direct proof could only be supplied if 

 it were possible to demonstrate which products of the anaerobic 

 metabolism are oxidised in the presence of oxygen and how this 

 oxidation takes place. Nevertheless the theory is and remains 

 a fruitful working hypothesis, the full meaning of which will 

 be demonstrated in the next section. On this account it has 

 usually been favorably received, particularly in its modern 

 form (as the oxidation of the intermediate products of fermen- 

 tation), especially since it has turned out that the ''intermediate 

 products of fermentation" actually exist. Alcoholic fermen- 

 tation has proved to be a complicated process. 



Only Maquenne and Boysen-Jensen have recently raised 

 objections to the general validity of the theory of connection. 

 Maquenne and Demoussy^ have found that foliage leaves are 

 quickly ruined in an atmosphere entirely free of oxygen. The 

 writers perceive in this a contradiction to the theory of 

 connection which appears to the author of these lines to be 

 hardly correct. If the respiratory processes be considered from 

 the energy standpoint it is evident that the heat released by 

 anaerobic respiration is very insignificant in comparison with 

 that of the oxidative processes, even if the latter take place to 

 only a limited extent. Just on this account plants go to ruin 

 when oxygen is excluded. If the anaerobic respiration be con- 

 sidered as a preparatory act, the importance of which consists 

 in the production of easily oxidised intermediate products of 

 alcoholic fermentation, it appears to be quite natural that this 

 intermediate stage of normal respiration of itself is not allied 

 with a development of energy. Moreover, the modern view 



' Maquenne, L. et E. Demoussy. Compt. rend. 173: 373. 1921. 



« By the word "alternately" {abwechselnd) Kostychev apparently means to 

 emphasize the progressive nature of the whole process of respiration. It refers 

 to the fate of a single molecule of respiratory material and does not suggest that 

 the tissue must be placed under first anaerobic and then aerobic conditions. — Ed. 



