418 MANUAL OF PHYSIOLOGY 



the food last eaten continues, and the waste materials are elimi- 

 nated in proportionately large quantity. When the influence of 

 the food taken prior to the commencement of starvation has 

 ceased, the daily amount of materials eliminated remains nearly 

 constant, and the body weight diminishes slowly until the ani- 

 mal's death. 



Adult animals commonly live until they have lost about half 

 of their normal body weight. Young animals die when they have 

 lost about 20 per cent, of their weight. 



Roughly speaking, we may take the body of a man to be made 

 up of the following proportions of the more important textures: 



Muscles, 50 per cent. 



Skin and fat,. 25 " 



Viscera, 12 " 



Skeleton, . , 13 " 



Seeing that the muscle tissue contributes such a large propor- 

 tion to the body weight, we cannot be surprised that in starvation 

 the greatest absolute loss occurs in this tissue ; except in the case of 

 excessively fat animals. Next comes adipose tissue, which almost 

 entirely disappears, the absolute loss from it varying in proportion 

 to the fatness of the animal at the beginning of the investigation. 

 The spleen and liver lose more than half their weight, and the 

 amount of blood is greatly reduced. The smallness of the loss 

 that occurs in the great nervous centres is very striking. They 

 seem to feed on the other tissues. 



The following table gives the approximate percentage of loss 

 which takes place in each individual tissue during starvation : 



Fat, 97.0 per cent. 



Muscle, 30.2 



Liver, 56.6 



Spleen, 63.1 



Blood, 17.6 



Nerve centres, 0. 



With regard to the portals by which the various materials make 

 their escape, it has been found that practically all the nitro- 

 gen passes off with the urine, and about nine-tenths of the carbon 

 escapes by the lungs as CO 2 , the remaining one- tenth passing off 



