206 



MAlsrUAL OF CATTLE-FEEDIKG. 



practically covers tlie comparatively sliglit increase of urea 

 observed on the working days, and we must consequently 

 assume tliat muscular exertion dues not essentially increase 

 tlie protein consumption in the body. 



Experiments by Pettenkofer &: Voit. — The correct- 

 ness of this conclusion is shown by some subsequent ex- 

 periments by Pettenkofer & Voit * on a man, in which 

 the amount of water drunk was regulated, and the above- 

 mentioned source of uncertainty thus avoided. In these 

 experiments the respiratory products were also determined, 

 and the influence of work upon the non-nitrogenous con- 

 stituents of the body thus ascertained. 



On the work-days the subject of the experiments turned 

 for nine hours,^ with occasional pauses, a heavy wheel pro- 

 vided with a brake, and at xiiglit felt fatigued as after a 

 hard day's work or a long march. With the aid of the 

 respiration apparatus the following numbers, which all refer 

 to a space of twenty-four hours and are mostly the average 

 of two or three concordant experiments, were obtained : 





NitK^en 



of urine. 



Grras. 



Carbonic 

 acid ctx- 

 croted, 

 Grms. 



Watek Excreted. 



Oxygon 



takon up. 



Grms 



Niimbor 





In urmo 

 Grras 



Evaporated. 

 Grms 



of expoi 1- 

 monts. 



Fasting. 



Best 



Work... 



AVEBAGE BiBT. 



Rest 



Work 



12.4 

 12.3 



17.0 

 17.3 



710 

 1,187 

 • 



928 

 1,209 



1,006 

 740 



1,218 

 1,155 



821 



1,777 



931 



1,727 



762 

 1,072 



832 

 981 



2 

 1 ' 



S 



2 



These figures prove most decidedly that the protein con- 

 sumption is no greater during work than during rest, but 



* ZeitBGhxiit L Biologie, TI , 478-500, 



