MANUAL OF CATTLE-FEEDIFG, Oa 



stance, but tlie differences observed by tliem were far 

 smaller than those oljtained by mocst other obbervers. 



Bidder and Schmidt * appear to have been the iirst to 

 express the opinion that nitrogen leaver the body only in 

 the visible excretions ; but their experiments were too few 

 in number to prove the point, and shortly af terw ard Bis- 

 choff t pnblished the results of nnmerons experiments on 

 dogs, in which he observed a considerable deficit, a vei ag- 

 ing 30 per cent. Iloppe-Seyler also foinid a deficit t»f 15 

 per cent, in an experiment in which a dog was fed for 

 seven days exclusively on meat. 



Voit's Experiments, — Karl Voit, in Munich, was the 

 first to furnish decisive proof that the urine and dung arc 

 the sole channels by which nitrogen leaves the body, aiid 

 that the nitrogen of the urine is an accurate measure of 

 the amount of nitrogenous matters decomposed in the body. 



He showed, in his " Physlologiseh-Ghemische Uht^muck- 

 ungen^^^ published in 1857, that the large deficit of nitrogen 

 observed previously was due to faulty methods of experi- 

 ment, and found in his own experiments either an equal- 

 ity between the nitrogen of food and excrements or dif- 

 ferences which were explained veiy simply by the gain or 

 loss of flesh by the animal under experiment. 



Since that time a vast number of similar experiments, 

 chiefly on dogs, have been made in the Physiological Insti- 

 tute at Munich by Voit, in conjunction with BischofE and 

 later with v. Pettenkofer, which have fully confirmed the 

 results of the earlier ones and have been of the greatest 

 service in elucidatina* the laws of the formation of flesh in 

 the animal body. The following are a few of the results : \. 



* **Die VerdauTingsfeafte u. der Sfcoffwechsel,%1852. 

 f '' Der Harnstoff als Mass des Stoffwechselb," 1853, 

 J Wolff: "Ernalirung Landw. Nutztlxierej" p. 249. 



