Till. CARBON BALANi 549 



Influence of Metabolism. Apart from diet, the respiratory quotii 

 may often be altered by changes in the metabolic habits of the animal. 

 These are mosl conspicuously exhibited in the ■ -. hibernating 



animals. In the autumn months, when the animal is eating voraciously 

 of all kinds of carbohydrate food and depositing large quantil 

 adipose tissue in his body, the respiratory quotient may be ably 



greater than unity, indicating therefore either that relatively m 

 carbon dioxide is 1 > < • i 1 1 <_r discharged or Less oxygen retained As i matter 

 of Pact, it can easily be shown thai it is the former of the causes thai 

 is responsible for the higher quotient, the explanation for the inc 

 production of CO s being that, as the carbohydrate changes inl t, the 

 relative excess of carbon in the former is go1 rid of as CO,, as indici 

 in Equation 5. On the other hand, if the animal is examined while in 

 his winter sleep, it will be found thai the respiratory quotienl is now 

 extremely low, often qo1 more than 0.3 to 0.4, which may be interpr< 

 as indicating either an excessive absorption of oxygen or a markedly 

 decreased excretion of carbon dioxide. As a matter of fad 

 ureal diminution in both the excretion of carbon dioxide and the intake 



of O a , 1 ause the whole metabolic activity of the animal is • tely 



depressed, but this diminution affects the oxygen to a much less deg 

 indicating therefore a relative increase in the oxygen tion. '1 



explanation is thai the oxygen is being used in the chemical process in- 

 volved in the conversion of the fat back into carbohydr 



Whatever may be the relationship between fat and carbohydrate in 

 the nonhibernating animal, there is no doubt thai during hiberna- 

 tion, before the fat stores are burned, fat is converted into something 

 closely related to carbohydrates, the equation for the process being • 

 resented as gn en above No. 4). 



In man and the higher mammalia, the only condition apart from diet 

 which can affect the nature of the combustion process is disease; thus 

 in total diabetes (page 678) the organism loses the power of burning 

 carbohydrate, so thai whatever the diel may be, the respirai 

 is very low, never higher than thai representing combustion of fat and 

 protein. It has been claimed bj certain investigators that in diabi 

 the respiratory quotient may fall considerably below 0.7, indicati 

 in hibernating animals, that fat is being converted into carbohydr 

 The most recent and carefully controlled observations, h< 



this claim, and for the present we must assume that in the bod 

 fat is not converted into enrbohydrat In numei 



diseases investigated b) Du Bois ami others' no qualitative change in 

 the combustion processes in man has been brou jht. 



