REPAIR AND WASTE 29? 



These latter are not by any means of a definite form, and 

 but for vital direction they might form very anomalous 

 combinations. 



ANIMAL HEAT 



The term "animal heat" we, in common with other 

 writers, use here merely to express the heat of the body, 

 without attempting to distinguish one animal from 

 another. Its generation in the system is of vast im- 

 portance to health, over which it exercises a most control- 

 ling influence. It is proper, therefore, that we consider 

 the subject somewhat at length here. 



The generation of animal heat has been referred to in 

 a previous chapter, where the agency of oxygen in the 

 metamorphosis or change of materials composing the tis- 

 sues of the organs was discussed. It may here be said 

 that in the course of all these changes modifications are 

 constantly taking place in the relative condition of caloric, 

 whether sensible or latent in its state. Oxygen has never 

 been known to combine with any other element without af- 

 fecting, to some degree, the temperature of the substances 

 concerned. In the animal body, it is true, oxidation 

 never goes on so rapidly as in conflagrations in the open 

 air; yet, as may be seen in the process of respiration alone, 

 a great amount of oxygen is taken into the system, but it 

 is breathed out again with the expired air, not, however, 

 in the same form in which it was taken in: it is simply 

 being mechanically received and combined with nitrogen, 

 and given off chemically united with carbon in the form of 

 carbon dioxid. While it is known that such a combination 

 of oxygen and carbon cannot take place, either in or out 

 of the body, without causing the evolution of a large 

 amount of heat, it is by no means difficult to believe that 

 what is called animal heat has its source in this phenome- 

 non. It may be well to suggest that the union that occurs 



