238 A Manual of Veterinary Physiology. 



It is necessary to remember that the amount of heat 

 yielded by a body in a calorimeter may be much greater 

 than the quantity of heat which the same substance will 

 yield when oxidized in the body ; particularly is this the 

 case with albumin, which in the system is never fully 

 oxidized, as so much of it — one- third — passes off as urea. 

 The albumin in the above table has been corrected for this 

 loss. 



Loss of Heat. — The chief seat of heat production is the 

 muscles ; heat is also produced in the liver and other 

 glands. Of the total amount produced, some is lost by 

 radiation and evaporation from the skin, and in other ways. 



The amounts may be expressed as follows : 



Warming solids and liquids 2 per cent. ) 7 . ) 



air of lungs -5 „ ] ' per cent - \ 15 per cent. 

 Evaporation from lungs, say 8 or 1) per cent. ) 



» ? kin I - - - 85 



Radiation from skin ( 



Conduction (ordinarily) - - - - „ 



100 per cent. 



The bulk of the loss is due to evaporation by the skin, 

 and the heating of the inspired air, food, water and 

 feces, and only a small and varying proportion is due to 

 radiation. 



The amount of heat lost by the skin is therefore con- 

 siderable. The object of this loss is to regulate the body 

 temperature. When animals are varnished, so as to prevent 

 evaporation, the heat of the body does not accumulate as 

 we might expect; on the other hand, a fall in temperature 

 occurs and death shortly follows, the explanation being 

 that the varnish has proved such a good conductor of heat, 

 that more is passing away from the animal than under 

 normal circumstances. If this rapid conduction of heat 

 be prevented by rolling the animal up in wool, death does 

 not follow. 



The hairy covering on animals prevents loss of heat by 

 conduction, hair being a bad conductor. When, however, 

 hair is wet, as in sweating horses, it becomes a conductor of 



