382 FAT METABOLISM. OBESITY 



to the reality of assimilation of foreign fats. However, it is 

 not well known even at present to what degree the body 

 changes this acquired fat, and, as it were, impresses upon it 

 the stamp of its own individuality. We know, it is true, that 

 the fats of different genera of animals present nearly con- 

 stant characteristics. As far as the fat which is formed 

 within the body (probably from carbohydrates) is con- 

 cerned, there is nothing remarkable in this. But in case of 

 the fat which is acquired directly from the food, this would 

 demand a constancy in the food which certainly does not 

 always obtain (providing the fat does not undergo secondary 

 changes). Gr. Eosenfeld found, as a matter of fact, that a 

 dog which had been stuffed with mutton suet continued a 

 month after interrupting the fat diet to show a pure mutton 

 fat in his tissues ; and he was of the opinion that a panther, 

 for instance, if he would devour nothing but sheep would 

 necessarily put on sheep fat. He found, too, that gold fish 

 and carp when fed mutton suet deposit this form of fat; 

 and comparison of the fats of various marine forms with the 

 fats of their customary foods showed a widespread similar- 

 ity between them. The same seems to be true, too, for 

 vegetarian animals, although in these, besides the fats con- 

 tained in the food, there is also that which is formed in the 

 economy from carbohydrates. "Thus we find," says 

 G-. Eosenfeld, 9 "that the herbivorous animals have a firm 

 fat, poor in oleic acid, while the graminivora have a soft fat. 

 The fat of the food shows almost precisely the same char- 

 acteristics ; green food has a firm fat, seeds contain a soft 

 oil. If a horse becomes fat from feeding on oats, his fat will 

 be fluid; if he has been fattened on hay, his fat is much 

 firmer. The similarity of the tallow from the ox, sheep, roe 

 and hart is referable to the similarity of food, i.e., grasses." 

 Transformation of Fat in the Body\. Be these discov- 

 eries as illuminating as they may, we have, however, no sub- 

 stantial reason for doubting the ability of the body to adapt 



1. c.,p. 676. 



