PLANT RESPIRATION 



I. OXYGEN RESPIRATION 

 I. THE GENERAL CONCEPTION OF OXYGEN RESPIRATION 



The most important vital processes are bound up with an 

 expenditure of energy. Thus most syntheses of organic sub- 

 stances, such as the synthesis of proteins, represent endothermic 

 reactions. In the same way the various types of architectural 

 processes of tissue differentiation require a supply of energy. 

 Accordingly there are found in all organisms specific material 

 transformations, the sole aim of which is to develop free energy. 

 Certain chemical reactions which are attended by the formation 

 of heat serve as energy-producing processes. Such of these 

 processes as proceed in the absence of oxygen are called fermen- 

 tations. They are peculiar to a limited group of microorgan- 

 isms. Vital oxidation processes are more widely distributed, 

 result in a considerable development of energy, and are generally 

 designated as oxygen respiration" or simply respiration. 



Lavoisier has already pointed out that the respiration of 

 animals is to be interpreted as a slow combustion, in which oxy- 

 gen is consumed and carbon dioxide is liberated. The classic 

 investigations of Th. de Saussure^ showed that plant respiration 

 is essentially identical with the respiration of animals, since the 

 absorption of oxygen and the formation of CO2 are likewise 



• de Saussure, Th. Ann. de chim. 24: 135, 227. 1797; Recherches chimiques sur la 

 vegetation. P. 8 and 60. 1804. 



° Kostychev's use of the term "Sauerstoffatmung" rather than "aerobe 

 Atmung" is quite in line with the present tendency to avoid the impHcations 

 involved in the use of the contrasting terms — aerobic and anaerobic respiration. 

 The best criticism of the older usage is to be found in an article by W. M. Clark 

 (Jour. Wash. .\cad. Science 14: 123-138. 1924). The term "oxygen respiration " 

 may seem strange but it has the merit of emphasizing the oxidative features of 

 this phase of respiration. There seems to be no way of avoiding a literal trans- 

 lation of the phrase "anaerobe .\tmung" as "anaerobic respiration." — Ed. 



I 



