118 TRUE NATURE OF THE 



remain 108 cubic inches of nitrogen, which occupy 

 the space of 3 Ibs. of water. Now whatever may be 

 the actual amount of the nitrogen thus swallowed, 

 it is certain that the whole of it is given out again 

 by the mouth, nose, and skin ; and when w r e consider 

 the very large quantity of nitrogen found in the in- 

 testines of executed criminals by Magendie, as well 

 as the entire absence of oxygen in these organs (26), 

 we must assume that air, and consequently nitrogen, 

 enters the stomach by resorption through the skin, 

 and is afterwards exhaled by the lungs. 



When animals are made to respire in gases con- 

 taining no nitrogen, more of that gas is exhaled, 

 because in this case the nitrogen within the body 

 acts towards the external space as if the latter were 

 a vacuum. (See Graham, " On the Diffusion of 

 Gases.") 



The differences in the amount of expired nitrogen 

 in different classes of animals are thus easily ex- 

 plained ; the herbivora swallow with the saliva more 

 air than the carnivora ; they expire more nitrogen 

 than the latter, less when fasting than immediately 

 after taking food. 



13. In the same way as muscular fibre, when 

 separated from the body, communicates the state of 

 decomposition existing in its elements to the per- 

 oxide of hydrogen, so a certain product, arising by 

 means of the vital process, and in consequence of the 

 transposition of the elements of parts of the sto- 

 mach and of the other digestive organs, while its own 



