COMPOSITION OF ANIMALS AND OF FEEDING STUFFS 65 



body and may be stored up in large quantities, reaching in one 

 instance 48 per cent, or, on the other hand, may be almost lack- 

 ing in the insufficiently fed or fasted animal. 



98. Composition of fat-free body. Since the adipose tissue 

 of the animal body represents substantially a storage of reserve 

 material (93, 94) temporarily set aside from the physiological 

 activities of the organism, a better idea of the composition 

 of the working machinery of the body is obtained by computing 

 its composition fat-free as in Table 18. 



When this is done, it appears that the composition of the fat- 

 free body is much less variable than that of the body as a whole, 

 the chief difference being due to variations in the water content, 

 which in turn depends chiefly upon the age of the animal, as 

 the preceding table shows. So far as can be concluded from 

 these few cases, however, the fat-free bodies of mature cattle 

 would appear to contain three to four per cent less water than 

 those of mature sheep or swine. In the case of geese, the per- 

 centage of water is probably low on account of the relatively 

 small amount in the feathers. 



99. Composition of fat- and ash-free dry matter. In some of 

 the foregoing investigations, viz., in Lawes and Gilbert's, Sox- 

 hlet's and three of Chaniewski's, the total nitrogen was deter- 

 mined and the protein has been calculated by multiplying by 

 the factor 6.25. These experiments permit a computation of 

 the percentage of nitrogen contained in the fat-free dry matter 

 which in the other experiments has been regarded as protein. 

 For example, in the case of Lawes and Gilbert's fat calf the figures 

 are as follows : 



Per cent 



Total dry matter 34.9 



Ash 3.9 



Fat 15.3 19.2 



Fat- and ash-free dry matter . . . 15.7 

 Total nitrogen 2.537 



2 -537 * J 5-7 = 16.16% nitrogen in ash- and fat-free dry 

 matter. 



The results of such a computation for all of the experiments 

 in which the published data permit it are contained in 

 Table 19. 



