1G2 MAKUAL OF CATTLE-EEEBINa 



An experiment on tyrosin showed that a part of tins sub- 

 stance wab converted into urea, but that a considerable por- 

 tion escaped digestion. 



Similar experiments by v. Knieriem* on asparaginic 

 acid and asparagin, gave similar results. They showed 

 that these bodies are converted into urea in the animal 

 body, and gave also a deficit of nitrogen, though a smaller 

 one, amounting to 9 to 10 per cent- of the amide nitrogen 

 fed. Further expeiiments by the same author f on hens, 

 with asparagin, asparaginic add, glycocol, and leucin, gave 

 also the same result, though with a still smaller deficit of 

 nitrogen. In no case, however, was the excretion in ex- 

 cess of the supply in the food. 



Indications of Nutritive Value. — ^AU these results, 

 while highly interesting, leave the question of the nutri- 

 tive value of amides still in doubt. There are many facts, 

 however, which indicate that they may have a certain vahie 

 as food. The very fact that they are decomposed in the 

 body is one. Another is, that they are formed from the 

 albuminoids of the food, to a considerable extent, by the 

 action of the trypsin of the pancreatic juice in digestion. 

 It seems hardly probable that the amides thus formed are 

 to be regarded as waste products. Moreover, we have seen 

 that in the plant these bodies may serve as sources of pro- 

 tein, and while such synthetic processes are particularly 

 characteristic of vegetable life, they are by no means ex- 

 cluded in the animal organism. 



That, under certain circumstances, an amide may have a 

 high n;tritive value, has been sl^ikingU shown by Her- 

 mann. It had been shown by Voit and others that gela- 

 tin and similar bodies, belonging to the gelatigenous group 



* Zeitschrif fc fur Biologie, X., 279. 

 t Ibid , XIII , M, 



