II. ANAEROBIC RESPIRATION 

 I. THE GENERAL CONCEPTION OF ANAEROBIC RESPIRATION 



Since we consider oxygen respiration of plants as a slow 

 combustion of sugars and other organic substances, the ques- 

 tion arises, how can such combustion of sugar take place in 

 living cells at low temperatures? We know that sugar solu- 

 tions themselves show no alteration after standing a year at 

 room temperature under sterile conditions, and sugar especially 

 is not at all oxidised with complete access to air. The sugar 

 content of the solution remains constant by the year. Various 

 facts described below, among which the process of so-called 

 anaerobic respiration really occupies first place, furnish the kev 

 to the solution of this most highly interesting and important 

 puzzle. This noteworthy vital phenomenon must now be 

 described exhaustively. 



In the course of his epoch-making studies of fermentation. 

 L. Pasteur made the notable observation that various plants 

 and parts of plants hberate CO2 even in an oxygen free atmos- 

 phere. At the same time ethyl alcohol is formed in the tissues. 

 The formation of alcohol by seed-plants was estabhshed beyond 

 question by Pasteur^ himself as well as by his students, Lechar- 

 tier and Bellamy.- This discovery was not accidental. It is 

 rather a consequence of Pasteur's theory of fermentation, which 

 Pasteur first expressed in relation to yeast and supported by 

 ingenious experiments. This theory says: "Fermentation is 

 life without oxygen." According to Pasteur's view, the 

 energy requirement of yeast plants is satisfied by ordinary 

 oxygen respiration with complete access to oxygen. When 

 oxygen is excluded alcoholic fermentation commences as the 

 substitute source of energy. Continued life and even increase 



1 Pasteur, L. Compt. rend. 75: 784. 1872; Etudes sur la biere. 1876. 



2 Lechartier et Bellamy. Compt. rend. 6g : 356, 466. 1869; 75: 1203. 1872; 79: 1006. 

 1874- 



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