422 NUTRITION. 



in the body endowed with the special function of calorifica- 

 tion, but every part in which the nutritive forces are in 

 operation produces a certain amount of heat; and this is 

 probably true of the blood-corpuscles and other anatomical 

 elements of this class. The production of heat in the body 

 is general, and is one of the necessary consequences of the 

 process of nutrition; but, with nutrition, it is subject to 

 local variations, as is strikingly illustrated in the effects of 

 operations upon the sympathetic system of nerves, and the 

 phenomena of inflammation. 



Relations of Animal Heat to the different Processes of 

 Nutrition. Nutrition involves the appropriation of matters 

 taken into the body, and the production and elimination of 

 effete substances. In its widest signification, this includes 

 the consumption of oxygen and the elimination of carbonic 

 acid ; and, consequently, we may strictly regard respiration 

 as a nutritive act. All of the nutritive processes go on to- 

 gether, and they all involve, in most warm-blooded animals 

 at least, a nearly uniform temperature. During the first 

 periods of embryonic life, the heat derived from the mother 

 is undoubtedly necessary to the development of tissue by a 

 change of substance, analogous to nutrition, and even supe- 

 rior to it in activity. During adult life, animal heat and the 

 nutritive force are coexistent. It now becomes a question 

 to determine whether there be any class of nutritive prin- 

 ciples specially concerned in calorification, or any of the nu- 

 tritive acts, that we have been able to study by themselves, 

 which are exclusively or specially directed to the mainte- 

 nance of the temperature of the body. These questions 

 simply involve a review of considerations with regard to the 

 relations of various of the functions to the production of 

 heat. 



The supply of the waste of tissue being effected by meta- 

 morphosis of alimentary matter a process, the exact nature 

 of which we have not been able to determine it has thus 



