HEAT AND LIFE. 131 



modifiers of intensity of combustion in breathing ; but there 

 are such order and harmony, such foresight, one may say, in 

 the organization of the system, that its temperature con- 

 tinues definitively nearly the same in the physiological 

 state. 



The temperature of the human body, at the root of the 

 tongue or under the armpit, is about 37 (cent.) ; this figure 

 expresses the mean found in taking the temperatures of dif- 

 ferent points of the body, for there are certain slight varia- 

 tions in this respect in passing from one organ to another. 

 The skin is the coolest part, and the more so the nearer we 

 come to the extremities. The temperature rises, on the 

 contrary, with increasing depth of penetration into the or- 

 ganism: cavities are much warmer than surfaces. The 

 brain is cooler than the viscera of the trunk, and the cellular 

 tissue cooler than the muscles. Nor does the blood have 

 the same temperature in all parts of the body. The labors 

 of Davy and Becquerel established the fact that the blood 

 is warmer the nearer to the heart examinations are made. 

 Claude Bernard measured, by methods of equal ingenuity 

 and exactness, the temperature of deep vessels and the 

 cavities of the heart. He showed that blood, in passing 

 out from the kidneys, is warmer than when it enters, and 

 the same is true of blood passing through the liver. He 

 ascertained, too, that the vital fluid is chilled in going 

 through the lungs, and consequently the temperature of the 

 left cavities of the heart is lower than that of the right, by 

 an average of two-tenths of a degree. The last fact clearly 

 ^proves that the lungs are not the furnace of animal heat, 

 and that the blood, in the act of revivification, grows cool 

 instead of warm. 



Ancient physiologists supposed that life has the power 

 of producing heat ; they conceived of a kind of calorific force 

 in organized beings. Galen imagined that heat is innate 

 in the heart the chemic-physicians attributed it to fer- 



