THE INFLUENCE OF CHEMISTRY. 99 



during the process of digestion, without any material change 

 in its general character ; he simply ascribed to the animal 

 organism the power to convert, not only substances like 

 starch and sugar, but also nitrogenous compounds, into neu- 

 tral animal fats. 



Practical observations as well as scientific considerations 

 furnished the arguments for his views. The large accumu- 

 lation of fat noticed in well-fed cattle, sheep," pigs, and fowls 

 €ould hardly be ascri])ed to the amount of fat found in the 

 food consumed. Men living largely on a diet rich in starch 

 and in sugar, as a rule, are more apt to accumulate fat than 

 those living mainly on meat. On the other hand, the pecu- 

 liar action of the saliva on starch, changing it into sugar, and 

 of certain nitroo-cnous substances on the latter, changino- the 

 sugar into acids found in natural fats, besides the well- 

 known degeneration of muscles and flesh parts of the animal 

 body, into fat, rendered it quite probable that similar agen- 

 oies operating in the animal system could produce the ani- 

 mal fats from non-nitrogenous, as well as from nitrogenous, 

 constituents of the vegetable food consumed. 



These teachings of Liebig were at first received with much 

 opposition, yet they aie to-day still held worthy of the most 

 serious consideration. The subsequent careful investigations 

 of Dumas, Persoz, Bousinirtiult, Lawes and Gilbert, and oth- 

 ers, confirm the insufficiency of the fats contained in the food 

 consumed, to account for the exceptionally large accumula- 

 tion of fat in many successful and economical cases of stock 

 fattening. 



The same experimenters recognize also the beneficial in- 

 fluence of a liberal supply of nitrogenous food wherever an 

 alteration of starch or sugar into fats has to be assumed to 

 explain an exceptional accumulation of that substance in the 

 animal system. One of the best authorities in practical 

 stock feeding of to-day (J. Kiihn) states without reserve, in 

 his late advice to farmers, that wherever the fodder contains 

 a liberal supply of starch or of sugar, they may be considered 

 an ofi'set for a deficieni-}" in fat. 



The real weakness in Li('l)ig's views regarding the origin 

 of fats in animals consists more in the fact that we arc not yet 

 able to give a satisfactory explanation regarding the precise 



