gS PLANT RESPIRATION 



lower organisms. The mode of operation of the zymase isolated 

 from seed-plants and aerobic molds is just Uke that of zymase 

 from yeast. In both cases oxygen has no effect on the process 

 of formation of alcohol. These results show that the absence 

 of alcohol in living aerobic plants under normal conditions can- 

 not be attributed to a restraint of the enzymes of fermentation 

 but to the further use of the products of fermentation. All 

 theories which dispute the genetic connection between anaerobic 

 and normal respiration must furnish a satisfactory explanation 

 for the absence of the formation of ethyl alcohol when air is 

 admitted, and indeed for the fact that the action of zymase in 

 seed-plants and aerobic fungi is not checked by oxygen. 



Carboxylase, an enzyme which separates CO2 from a-ketonic 

 acids and is admitted to be a constituent part of the complex of 

 enzymes of fermentation which is included in the term zymase 

 was found in seed-plants by Zaleski.^ In Hke manner hexose- 

 phosphatase, an enzyme which esterifies sugar with phosphoric 

 acid and likewise probably participates in alcoholic fermenta- 

 tion, was found to be present.^ 



It is very worthy of note that Meyerhof^ found that the 

 alcoholic fermentation of yeast is strongly stimulated by an 

 aqueous extract of animal muscle or of germinating plants. 

 Conversely, yeast extracts increase the normal respiration of 

 plants as Kostychev^ has pointed out before. 



Meyerhof alludes to the necessity of the same "coenzymes" 

 for the normal respiration of animal tissue as for yeast fermenta- 

 tion. Hexose phosphate particularly is said to be just as indis- 

 pensable for the enzymatic oxygen respiration as for the enzymatic 

 alcohohc fermentation. Although the idea of coenzymes is 

 very indefinite,'' these results of Meyerhof by agreeable inter- 

 pretation favor the assumption that there is a genetic connection 

 between fermentation and respiration. 



» Zaleski, W. und E. Marx. Biochem. Z. 47: 184. 1912; Zaleski, W. Ibid. 48: 175. 

 1913: Ber. d. bot. Ges. 32: 457. iQM; Bodnar, J. Biochem. Z. 73: 193. 1916. 



2 Nemec, A. und F. Duchon. Biochem. Z. 119: 73- 1921. 



3 Meyerhof, O. Arch. ges. Physiol. 170: 367. 428. 1918; Z. f. physiol. Chem. loi : 165. 

 1918; 102: I. 1918. 



< Kostytschew, S. Biochem. Z. 15: 164. 1908; 23: 137- 1909; Kostytschew, S. und 

 A. Scheloumow. Jahrb. f. wiss. Bot. 50: 157. 191 1; Ber. d. bot. Ges. 31 : 422, 432. 1913. 



5 Cf. also Abderhalden, E. und H. Schaumann. Fermentforschung. 2 : 120. 1918; 3 : 44- 

 1919. 



