488 THE RESPIRATORY EXCHANGE 



body. Voit and Chauveau maintain that fat may form sugar, which 

 in turn may be stored up as glycogen in the liver and muscles. This 

 process would explain the low respiratory quotient exhibited by 

 hibernating mammals, for it is well known that they possess a large 

 deposit of fat which gradually disappears during the period of 

 torpidity ; moreover, it has been shown by various observers that 

 glycogen accumulates during hibernation. If olein be taken as an 

 example, the partial oxidation may be represented as follows : 



2C 2 H 5 (C 18 H 23 2 ) 3 + 640 2 = 16C H 12 O 6 + 18C0 2 + 8H 2 



2 18 0-281 

 ~ = = 



During the germination of fatty seeds, such as those of the 

 radish, the respiratory quotient is low, for the seeds take up a 

 relatively large amount of oxygen ; the fat undergoes partial 

 oxidation and gives rise to carbohydrates. 



The evidence, therefore, in favour of oxidation taking place 

 in the body without an immediate and corresponding production 

 of carbon dioxide is satisfactory, for it cannot be well maintained 

 that the carbon dioxide is formed but not discharged. It will 

 be shown later that in man and other animals respiratory quotients 

 below the value for the combustion of fat have been observed 

 by Zuntz, Lehmann, and others ; such quotients may persist for 

 hours or even days, if the conditions be favourable. 



The hibernating mammals likewise yield evidence of the pro- 

 duction of carbon dioxide without a corresponding absorption 

 of oxygen ( 8 ). During the autumn the marmot feeds eagerly upon 

 food consisting chiefly of carbohydrates, and rapidly deposits fat 

 in its body as a reserve for consumption during its winter sleep. 

 The respiratory quotient is during this deposition of fat constantly 

 greater than unity, and may be even as high as T39. Such high 

 quotients cannot be explained by a reduction in the absorption 

 of oxygen, for compared with the condition during fasting there 

 is a considerable increase. The probable explanation is that 

 suggested by Hanriot ; during the formation of fat from carbo- 

 hydrates a considerable quantity of carbon dioxide is split off 

 from the carbohydrate molecule. The following equation is given 

 by Hanriot to represent the change : 



13C G H 12 6 = C 55 H 10i O 6 + 23C0 2 + 26H 2 O. 



