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CHAP. IV. Animal Heat. 



1. ANIMAL heat is distinguished from every other 

 example of heat by the circumstance, that it is maintained only 

 during the living state. 



2. The term animal heat is perhaps not altogether unob- 

 jectionable: because we find that the living structures possess an 

 elevation of temperature, where the characteristics of animal life, 

 namely, sense and voluntary motion, are wanting; while, on the 

 other hand, the generation of this heat does not proceed after the 

 extinction of the organic life. The term vital heat would perhaps 

 be therefore more correct; but as this is a matter of very little 

 consequence, I shall not affect peculiarity by insisting upon the 

 distinction. 



3. Animal heat being produced only so long as life continues, 

 and the chymical and mechanical agents in the structure, shewing 

 of themselves no disposition or ability to produce it ; we must infer, 

 from these facts, that that principle of life, we may according to 

 the last paragraph recur to our old phrase, and say, that organic 

 spirit hitherto spoken of, is in some way or other concerned in the 

 process of generating animal heat; and that heat so far acknow- 

 ledges a dependence upon this spirit. 



4. The formation of animal heat results either from the 

 function of some particular organ or organs; or the process is a 

 diffused one, as universal in the structures as the existence of the 

 spirit itself: the settlement of this point is one of importance. 



5. Now that heat is not produced especially or exclusively in 

 any one place, and from thence diffused all over the body, ap- 

 pears to be satisfactorily proved by the following circumstances: 

 1st, the medium of such diffusion must be either by the continuity 

 of the solid structures, either single or mixed, or by the circula- 

 tion of the blood. In either case, supposing, in illustration of the 

 first, that the central organs of the nerves are the source of Jieat, 

 and their branches the medium of its diffusion; or, in illustration 

 of the second case, that the lungs are the* source of heat, which is 

 in them imparted to the blood, and by it to the textures; I say, in, 

 either case, the temperature of the place, or source, where heat is 

 generated, should be considerably higher than in the places of its 

 remotest distribution. Thus, supposing heat to be generated only 

 in the lungs, these organs bear perhaps in regard to the whole. 



