CHAPTER IV 



METABOLISM 



(i) Fasting metabolism. 



ALTHOUGH an animal is entirely deprived 

 JTx. of food, it continues to live for some time. 

 During the period of starvation most of the organs 

 of the body, as well as the fatty tissue, decrease in 

 weight. In the excreta — faeces, urine, and pro- 

 ducts of respiration — there are, nevertheless, the 

 same substances found as when food was being 

 taken. 



An examination of the excreta shows that by 

 complete withdrawal of food the body loses pro- 

 tein (flesh) as well as nitrogen-free substances 

 (principally fat), and mineral compounds. For 

 example, a rabbit which weighed 2341 gr. (about 

 5 lbs.) was found, after starving for eighteen days, to 

 weigh only 1388 gr., a loss of 953, which is 407% 

 of the original body weight. From the excreta of 

 this animal it was calculated that the following 

 quantities of body protein and body fat had been 

 destroyed — 



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