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 orunder 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 adegree. 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- 
