144 CIRCULATING FLUIDS: 



the other hand a certain degree of animal heat is indispensably 

 requisite for those chemical processes which are the necessary 

 consequences of the proper organic development of the cells of 

 all tissues, and of their catalytic influence on the nutrient fluid, 

 the plasma of the blood. The animal heat is therefore to be 

 regarded as the product of those vital functions, for the due 

 exercise of which it is essentially requisite. The organism is 

 thus protected against the innumerable disturbing forces under 

 which it would otherwise succumb, in consequence of the vary- 

 ing temperature of the external world. The development of heat, 

 therefore, decreases with the diminution of the vital powers, with 

 the retarded circulation of the blood, with checked nutrition, 

 and with imperfect metamorphosis, while all the phenomena of 

 inanition, perfect destruction of power, and finally an asphyxiated 

 condition, are the consequences. 



As this cellular action, which is collectively exhibited in the 

 metamorphosis of the animal organism, may be regarded as 

 purely chemical, so the heat that is engendered thereby may be 

 considered as a consequence of these chemical processes, and 

 therefore all those functions of the organism which are necessary 

 for the preservation of life, contribute directly or indirectly to 

 the production of animal heat, which must be regarded as de- 

 veloped at every point at which metamorphosis is occurring, and 

 therefore not merely in the lungs, but in the whole peripheral 

 system. The absorption of oxygen, and its combination with 

 the carbon of animal matter, not only in the lungs, but in the 

 whole body, must, on that account, be regarded as the prin- 

 cipal source of heat. In addition to the oxygen required 

 for the formation of the carbonic acid, a certain amount is ab- 

 sorbed, which probably enters into combination with hydrogen, 

 or with binary or ternary radicals of carbon and hydrogen, of 

 carbon and nitrogen, or of carbon, hydrogen, and nitrogen, and 

 in this manner, doubtless, contributes somewhat to the general 

 production of heat. 



The theory of animal heat aff'ords a simple explanation of many 

 well-known phenomena, as, for instance, of the slight inde- 

 pendent warmth of the foetus, when removed from the uterus 

 (as shown by Autenrieth and Schidtz),^ and of those young 



' Experimenta circa caloreni foetus et sanguinem. Tub. 1799. 



