MAKUAL OF OATTLE-PEEBIJSrO. 1C3 



of compounds (p. 18), are capable of performing the func- 

 tions of circulatory proteiii; but cannot serve as a source of 

 organized protein. 



It was known also tbat when these bodies were decom- 

 posed by acids they yielded essentially the same products 

 as the albuminoids, except that the amide tyrosin was al- 

 ways lacking. Escher/ under Hermann's direction, tried 

 the experiment of feeding a dog with gelatin and tyrosin, 

 and found that the two together could sustain life and 

 cause a production of flesh. 



The very probable conjecture has been advanced, that 

 amides in the food may play the same part that gelatin 

 has been shown to do by Voit, viz., take the place of a por- 

 tion of the circulatory protein, thus leaving the latter avail- 

 able for the formation of flesh or for other productive pur- 

 poses, and this view seems to be sustained by the experi- 

 ments about to be described. 



Asparagin a Nutrient. — The only experiments as 

 yet executed with the direct purpose of determining the 

 food-value of amides are those of Weiske, Schrodt, and v. 

 Dangel,t at the Proskau Experiment Station, on aspara- 

 gin. A series of experiments on rabbits and another on 

 liens having shown only that albxmiinoids could not be 

 entirely replaced by asparagin, but giving in other respects 

 indecisive results, a third series was made on two merino- 

 southdown sheep. The plan of the investigation was as 

 follows : The animals were fed at first with a fodder poor 

 in protein (consisting of hay, starch, and sugar) until the 

 excretion of nitrogen in the urine became constant, and the 

 gain of flesh on this ration was determined. Then, in three 

 following periods, the amount of nitrogen in the daily ration 



* Vierteljahrssclirift der natnrf Gres. in Zuriclij XXI,, 30. 

 t Zeitsciinft fiir Biologie, XV , 2GX. 



