MAliTirAL OF OATTLE-FEEDING. 



formerly believed tliat, inversely, the foi-mcr was deter- 

 niined by the latter. If, by an increased supply of food 

 or by violent muscular exertion, this splitting up of the 

 niaterials of the body is increased and facilitated, then, 

 secondarily, more oxygen will be taken up, in order that 

 the resulting products may be oxidized. 



Storing xip of Oxygen. — ^We liave hitherto, for con- 

 venience, spoken as if the oxygen taken up by the blood 

 united at once in the capillaries with the products of tis- 

 sue chan«:e. 



Numerous experiments by Pcttenkofer and Voit,* at 

 Munich, and by Ilenneberg,t at the Weende Experiment 

 Station, have, however, shown that the animal body has 

 the power of storing up within itself a considemble amount 

 of oxygen, and that some time may elapse after oxygen is 

 taken up into the blood before it is excreted in combina- 

 tion with carbon and hydrogen, Tlie following experi- 

 ment by Pettenkofer and Voit, upon a healthy man on an 

 average diet, will serve to illustrate the point. The ex- 

 periment was divided hito two parts, the time from 6 a.m. 

 to 6 P.M. being designated as day and from 6 p.m. to 6 

 A.M. as niffht. 



If from the amount of carbon, hydrogen, oxygen, and 

 nitrogen, contained in the food eaten, we subtract* tlie 

 amounts excreted in organic combination in the solid and 

 liquid excrements, and also the amounts laid up in the 

 body in the form of fat, etc., the remainders will show 

 how much of each element must have been burned to car- 

 bonic acid and water in the body. This known, we can 

 ^-iy cdcdate fte amo™. of oxygen nece.a^' fa tl.e 

 process, and compare it with the amotint actually taken up 



* Zeit. f. Biologte, II., 552. 



f Neue Beifcriige, etc., 1871, p. 315. 



