82 MANUAL OF PHYSIOLOGY. 



which are mostly oxidizations, to go on. It is, in fact, the element 

 necessary for the slow combustion which takes place in the nutri- 

 ent material after its assimilation. 



Nitrogen also occurs in the blood, but in insignificant quantity. 

 It is absorbed from the atmosphere as the blood passes through 

 the lungs. So far as we know, it has no physiological importance 

 in the body. 



