THE CHEMICAL PROCESSES IN PLANT RESPIRATION 1 27 



effect of yeast extracts and fermented solutions to an increase 

 in the activity of respiratory enzymes by means of specific 

 coenzymes, or assumes, with Kostychev, the presence of easily 

 oxidised substances in fermented sugar solutions is not different 

 in principle. In both cases there is a connection between 

 fermentation and respiration. The following result could also • 

 be used in favor of the latter interpretation. It was shown^ 

 that fermented solutions hberate considerable amounts of CO2 

 in the presence of a ferrous salt and H2O2, whereas the system, 

 ferrous salt plus HoOo, is unable to oxidise plant protein as far 

 as the formation of CO2. The assumption is certainly not pre- 

 cluded that the coenzymes existing in fermented solutions raise 

 not only the oxidation potential of peroxidase but also that of 

 the ferrous ion. 



From the preceding exposition it is evident that various 

 experimental results support the theory of connection of 

 alcoholic fermentation with sugar respiration. This connection 

 may be schematically represented as follows, after Kostychev. ^ 



Fermentable Sugars 

 Intermediates of Alcoholic Fermentation 



/ I 



Fermentation Products Respiration Products 

 (CO2 and CH3— CH2OH) (CO2 and HoO) 



Palladin- has proposed an interesting theory to explain the 

 oxidation of the intermediates of fermentation. This theory 

 represents a combination of those of Bach-Engler and Wieland. 

 According to Palladin, the so-called respiratory chromogens 

 play a very important role in the respiratory process. Palladin 



' Kostytschew, S. loc. cit. 



2 Palladin, W. Ber. d. bot. Ges. 26a: 125. 378, 389. 1908; 27: loi. 1909; 29: 472. 

 1911130:104. I9I2;Z. f. physiol. Chem. 55: 207. 1908; Rev. g6n. de bot. 23 : 225. 1911; 

 Z. f. Garungsphysiol. i: 91. 1912; Palladin, W. und S. Lwow. Ibid. 2: 326. 1913; 

 PaUadin, W. und Z. Tolstoi. Mitt. d. Akad. d. Wiss. Petersburg 1913: 93- 



