FUNCTIONS OF ANIMALS. 



From this table, compared with the facts stated in the preced- 

 ing part of this section, it follows, that in a given time a man 

 consumes 50,000 times as much oxygen gas as a tench. Yet the 

 presence of this principle is equally necessary for the existence 

 of both. 



The experiments of M. Nysten on the effect of injecting oxy- 

 gen gas into the veins of living animals, made in 1811, show 

 that blood readily absorbs this gas. It would be an important 

 fact if it could be ascertained whether injections of oxygen gas 

 into the veins of living animals could be so far substituted for 

 respiration as to prolong the life of the animal. It would be 

 difficult, however, to make such an experiment in an unexception- 

 able manner. Were as much oxygen gas as the blood would 

 readily absorb injected into the veins of an animal, and were the 

 animal, together with another in its natural state, plunged into 

 a vessel filled with hydrogen gas, it might perhaps be ascertain- 

 ed whether the former would live longer than the latter. 



An interesting set of experiments, which throws considerable 

 light on respiration, was made by M. Boussingault in 183 P. * A 

 cow giving milk was fed with a quantity of food carefully weighed 

 out for three days, and the quantity of milk, faeces, and urine 

 emitted during that time was also determined. The food per 

 day was, 



Potatoes, . . 32-418 Ibs. avoirdupois. 



Hay (2d crop) . 16-535 



Water, . . 132-282 



It was necessary to determine ho\v much water the food contain- 

 ed. It was found to be as follows : 



Dry. Water. 



The potatoes consisted of, 9-08 Ibs. + 23-368 Ibs. 

 The hay of, . . 14-22 + 2-315 



Water, . . . 23-30 25-683 



132-282 



157-965 



So that the dry portion of the food was 23-3 Ibs., and the water 

 157-965 Ibs. 



The weight*of the milk, urine, and faeces was as follows : 



* Ann. de Chim. et de Phys. Ixxi. 113 and 128. 



