CHAPTER IX 



ANIMAL HEAT 



WARM-BLOODED and cold-blodded animals are respectively 

 designated as homoiothermous and poikilothermous. The former 

 have a body temperature that varies very little from a certain 

 normal which is characteristic for the species, while the tem- 

 perature of the latter varies directly with the medium in which 

 they live, although usually from a fraction to several degrees 

 higher. Man is warm blooded the normal temperature being 

 about 98.5 F. (36.87 C.). The temperature is not invariable, 

 and in the internal organs may be as high as 100 F. under 

 normal conditions. In the rectum the temperature is about 

 1 F. higher than in the mouth or armpit. The warmest blood 

 in the body is that coming from the liver during digestion, 

 and the coolest is that coming from exposed parts, such as the 

 tips of the ears and the nose. In health the temperature 

 varies slightly with the external temperature, age, exercise, 

 sex, constitution, etc. The temperature of a newborn child 

 is about 37.86 C. In the adult there is a diurnal variation of 

 1 to 1.5 F.; being lowest in the morning and highest late in 

 the afternoon. This corresponds to the usual temperature 

 ranges in fever. In ordinary pathological conditions the 

 temperature does not remain long at a point below 95 F. 

 nor above 105 F. without fatal results. Under conditions 

 of prolonged exposure to cold and the algid stage of cholera, 

 recovery has occurred after a bodily temperature as low as 

 75 F. On the other hand, in some cases of extreme fever, 

 as from sunstroke, recovery has been noted after a tempera- 

 ture of 110 to 112 F. 



It has been proved that the source of animal heat is the 

 potential energy of the foods. The latter is converted into 

 heat either directly as the result of chemical decompositions, 

 or indirectly through muscular movements, friction, etc. 

 About 90 per cent, is formed directly. The heat liberated by 



