III. THE CONNECTION OF OXYGEN RESPIRATION 

 WITH ANAEROBIC RESPIRATION 



I. REVIEW OF THE OLDER LITERATURE 



A discussion of the chemical processes in plant respiration 

 must precede an analysis of the aerobic and anaerobic material 

 transformations of respiration. All coherent theories of plant 

 respiration start with the assumption that anaerobic respira- 

 tion constitutes a prehminary step to oxygen respiration. 

 This theory, at present established by numerous facts, has 

 passed through an instructive evolution. 



Pasteur,^ the founder of the science of anaerobic respiration, 

 was satisfied with proof of the fact that an alcohohc fermenta- 

 tion is pecuhar to various lower fungi and seed-plants. He 

 occupied himself with questions of fermentation and dealt with 

 anaerobic respiration only from the standpoint of his theory 

 of fermentation. The normal oxygen respiration did not inter- 

 est him. 



Soon after, however, Pfliiger- proved that in the case of some 

 animals the Hberation of COo continues after oxygen is excluded. 

 Pfliiger characterised this formation of COo as intramolecular 

 respiration. According to Pfliiger's view, intramolecular 

 respiration is not an abnormal or pathological phenomenon. 

 On the contrary it constitutes an essential prehminary step to 

 normal oxygen respiration. According to Pfliiger, the latter 

 consists of two series of reactions. In the first, easily oxidised 

 substances are formed from the reserve respiratory material 

 and CO2 is hberated in the process. According to Pfliiger, all 

 these processes take place without the intervention of atmos- 

 pheric oxygen and so continue in a medium free of oxygen. The 

 second phase of respiration, according to Pfliiger, consists of 



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

 = Pfluger. .\rch. ges. Physiol. 10: 251. 1875- 



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