HEAT AND FORCE 185 



not represent a sweep of more than 2 F. The body temper- 

 ature may be looked upon as being a fairly constant quantity. 

 It varies scarcely at all with variations of external temperature, 

 so long as the heat- regulating apparatus is in order. An external 

 (dry) temperature of 212 F., or the extremely low temperature 

 of some regions, can be borne with very slight fluctuations in 

 that temperature of the body. The actual limits of internal tem- 

 perature consistent with the preservation of life are given by 

 Flint as 83 and 107 F. These temperatures cannot be long 

 endured. 



The fundamental fact to be kept constantly in mind is that 

 there is a continual production and a continual dissipation of 

 heat, in ways to be indicated presently. These two processes 

 are known as thermo genesis (heat production) and thermolysis 

 (heat loss) respectively. The preservation of the proper balance 

 between heat production and heat dissipation is known as 

 ihermotaxis. 



Supply of Heat and its Relation to Force. It is a matter of 

 common observation that the burning (oxidation) or any sub- 

 stance, as a piece of wood or an article of diet, is accompanied 

 by the evolution of heat. It is also known that heat may be 

 converted into force may be made to do work. The burning 

 of a fat or a sugar produces CO 2 and H 2 O ; the burning of a pro- 

 teid produces CO 2 and H 2 O, and additional substances. The 

 final products, and the amount of heat evolved, are precisely the 

 same whether the oxidation be rapid or slow. Now, the oxida- 

 tion of food is exactly what occurs in the human organism, though 

 that of the proteids is not completely effected; CO 2 and H 2 O are 

 produced from them, and the " additional substances" men- 

 tioned are represented by urea. This process, then, is the source 

 of body heat. To the supply thus furnished may be added a 

 little from reactions between non-energy producing materials in 

 the body, from warm foods and drinks, and from friction in the 

 vessels, joints, etc. 



