lO PLANT RESPIRATION 



consumption.^ In this case the respiratory quotient is very 

 small. 



In other cases, however, materials rich in oxygen, such as 



organic acids, might proceed to a complete combustion, which 



CO 



would bring about an appreciable increase in the value of -^ — 



For example, the respiratory quotient for the complete oxida- 

 tion of oxalic acid is theoretically 4 : 



2COOH— COOH + 02 = 4CO2 + 2H0O. 



CO2 _ 4 _ 



In the case of this oxidation the heat production is really 



CO 



insignificant. In the oxidation of tartaric acid .^ equals 1.6: 



U2 



2COOH— CHOH— CHOH— COOH + 5O.. = 8CO2 + 6H2O. 



CO2 8 



07 = 5 ^ "- ■ 

 Further on the evidence will be brought out that all reserve, 

 nitrogen free substances consumed by respiratory processes 

 are burned by way of the intermediate stage of sugar. By this 

 means the theoretical value of the respiratory quotients of the 

 above materials will naturally not be influenced. It is enlight- 

 ening that in the case of the transformation of a non-carbo- 

 hydrate into sugar exactly the same amount of oxygen is 

 separated or consumed which, with a direct combustion, brings 

 about the ''abnormal'' value of the respiratorv quotient. 



^CO. 



Hence in the respiration of oilv seeds, low values of ^^ would 



be observed," a condition which is connected with the fact that 

 fats change over into sugars.^ If fatty seeds are nourished with 



prepared sugar, ~fV~ reaches the normal value, i, since under 



vJ2 



these conditions a direct combustion of sugar ensues and the 

 respiration of fat is discontinued.^ In the case of the ripening 

 of oily seeds, on the contrary, the quotient is greater than i 



I Kostytschew, S. Physiol.-chem. Untersuch. uber Pflanzenatmung. 1910. Russian. 

 ' Godlewski, E. Jahrb. f. wiss. Bot. 13: 491. 1882. 



-< Liaskowski, N. Chemische Untersuch. uber die Keimung von Kiirbissamen. 1874. 

 Russian. 



* Polowzow, V. Untersuch. iiber die Pflanzenatmung. igoi. Russian. 



