THE METABOLISM OP THE BODY. 446 



augmenting the heat of the body. Heat is lost by the skin, 

 lungs, urine, and faeces. 



The division of foods into heat-producers and tissue-builders 

 is unjustifiable, as will appear from what has just been stated, 

 as well as from such faxits as the production of fat from proteid 

 food, thus showing that the latter is indirectly a producer of 

 carbonic anhydride, assuming that fat is oxidized into that 

 substance. 



ANIMAL HEAT. 



Though a large part of the heat generated within the body 

 is traceable to oxidations taking place in the tissues, it is better 

 to speak of the heat as being the outcome of all the chemical 

 processes of the organism ; and though heat may be rendered 

 latent in certain organs for a time, in the end it must appear. 

 While all the tissues are heat-producers (thermogenic), the ex- 

 tent to which they are such would depend, we should suppose, 

 upon the degree to which they were the seat of metabolic pro- 

 cesses ; and actual tests establish this fact. Thus, among glands 

 the liver is the greatest heat-producer ; hence the blood from 

 this organ is the warmest of the whole body. The muscles also 

 are especially the thermogenic tissue. 



The temperature of the blood in the hepatic vein is warmer 

 than that in the portal, a clear evidence that the metabolism of 

 this organ has elevated the temperature of the blood flowing 

 through it. 



The temperature of the blood (its own metabolism being 

 slight) is a pretty fair indication of the resultant effect of the 

 production and the loss of heat. 



For obvious reasons, the temperature of different parts of 

 the body of man and other animals varies. 



The statements of observers in regard to the temperature of 

 various animals and of different parts of the body disagree in 

 a way that would be puzzling, were it not known how difficult 

 it is to procure perfectly accurate thermometers, not to mention 

 individual differences. The axillary temperature is in man 

 about 37° C. (&8-6 F.); that of the mouth a little higher, and 

 of the rectum or vagina slightly more elevated. The mean 

 temperature of the blood is placed at 39° C. (102-2 F.). 



Comparative. — The temperature of various groups of animals 

 has been stated to be as follows : Hen and pigeon, 42° (107"6 F.) ; 

 swallow, 44-03° (111-25 F.) ; dolphin, 35-5° (95-9 F.) ; mouse, 41-1° 



