Formation of Fat in the Animal Body. 25 



not experience any change in the organism. All doubt may 

 be removed by the simplest experiments; it may be shown that 

 the excrements of the cow contain as much of the substances 

 soluble in aether as has been consumed in the food. The ex- 

 crements of a cow which was fed upon potatoes and grass were 

 dried and exhausted by aether; a green solution was obtained, 

 somewhat darker in colour than that given by hay, which upon 

 concentration owed its consistency to a white crystalline waxy 

 substance, which was surrounded by a dark green mother 

 liquor. Upon further evaporation it gave out an unpleasant 

 smell, and left when dried at 100° C, 3*119 per cent, of the 

 weight of the excrements of fat and similar substances. 



As M. Boussingault has found that the dried solid ex- 

 crements {Annal. de C/iim. et de Phys. t. lxxi. p. 322) amount 

 to four-tenths of the weight of the dried fodder, it is evident 

 that these excrements contain very nearly the same quantity 

 of fatty substances as the food consumed. 



1\ kilogr. of hay contain (at 1*56 per cent.) 116 gram, 

 of fat. The 15 kilogr. of potatoes contain further 10 gram, 

 of fat. In the whole, therefore, 126 gram, of fat. 



The solid daily excrements weigh 4000 gram. ; they contain 

 (at 3*119 per cent.) 124*76 gram, of fat. A cow which pro- 

 duces in six days 3116 gram, of butter, consumes in its food 

 during the same period 756 gram, of substances soluble in 

 aether, and gives off in her excrements 747*56 gram, of sub- 

 stances of the same nature and properties ; it must therefore 

 follow, that in the production of 6£ lbs. of butter in the milk, 

 these ingredients of the food can have no share. 



I consider I have now demonstrated that the fat which 

 accumulates in the bodies of animals during the fattening 

 process, and that the butter daily produced in the milk, do 

 not originate from the wax or chlorophyll of the food, but 

 from the other ingredients of it. I think I should be giving 

 myself unnecessary trouble to look after facts to correct 

 M. Dumas's peculiar opinion, because upon further consi- 

 deration it is of a nature to correct itself. 



It is similar to the idea of M. Payen, that the oil of po- 

 tato spirit (fusel oil) is ready formed and contained in po- 

 tatoes. But since it has been found that the last syrup 

 arising from the preparation of beet-root sugar produces in 

 the distillation of brandy a considerable quantity of fusel oil, 

 no one will doubt its formation during the process of fer- 

 mentation. 



The opinion of M. Dumas is a necessary consequence of 

 the exclusive hypothesis, that animals produce in their or- 

 ganism no substances serving as food (note quoted above), 



