FATS. 



75 



Fig. 15. 



TJRTNIFEROUS TUBULES OF DOG, from COr- 



tical portion of kidney. 



Fig. 16. 



A large part of the fat which is found in the animal body may be 

 accounted for by that which is taken in with the food, since oily matter 

 occurs in both animal and vege- 

 table substances. Fat is, how- 

 ever, formed in the body from 

 other organic substances, inde- 

 pendently of what is intro- 

 duced with the food. This 

 important fact has been defi- 

 nitely ascertained by the ex- 

 periments of MM. Dumas and 

 Milne-Edwards on bees, 1 M. 

 Persoz on geese, 3 and finally 

 by those of M. Boussingault 

 on geese, ducks, and pigs. 3 The 

 observers first ascertained the 

 quantity of fat existing in the 

 whole body at the commence- 

 ment of the experiment. The 

 animals were then subjected to 

 a definite nutritious regimen, 

 in which the quantity of fatty 

 matter was duly ascertained by 

 analysis. The experiments 

 lasted for a period varying, in 

 different instances, from thirty- 

 one days to eight months; 

 after which the animals were 

 killed and all their tissues ex- 

 amined. The result of these 

 investigations showed that con- 

 siderably more fat had been 

 accumulated by the animal 

 during the course of the expe- 

 riment than could be accounted 

 for by that which existed in 

 the food ; and placed it beyond 

 a doubt that oleaginous sub- 

 stances may be, and actually 



are, formed in the interior of the animal body by the decomposition or 

 metamorphosis of other proximate principles. 



There is reason to believe that fat is produced in this way, under the 

 influence of the vital process, from the transformation of starchy and 

 saccharine substances. In the first place, as we have already seen, there 



MUSCULAR FIBRES OF HUMAN UTERUS 

 three weeks after parturition. 



1 Annales de Chira. et de Phys., 3d series, vol. xiv. p. 400. 2 Ibid., p. 408. 



3 Chimie Agricole. Paris, 1854. 



