EQUALIZATION OF THE ANIMAL TEMPERATURE 407 



a diminution of the supply of fats, carbohydrates and- water in the food 

 prevents, to a certain extent, the new formation of fat. In excessive 

 muscular work, the production of water is increased and the circula- 

 tion becomes more active. The volume of blood then circulating in the 

 skin and passing through the lungs in a given time is relatively increased, 

 and there is an increased discharge of water from these surfaces. The 

 same condition that produces an increased quantity of water in the 

 body and has a tendency to exaggerate the process of calorification 

 seems to produce also an increased evaporation from the surface, which 

 serves to equalize the animal temperature. 



Equalization of the Animal Temperattire. There is always more 

 or less loss of heat by evaporation from the general surface ; and when 

 the surrounding atmosphere is very cold it becomes desirable to reduce 

 this loss to the minimum. This is done by appropriate clothing, which 

 certainly must be regarded as a physiological necessity. Clothing pro- 

 tects from excessive heat as well as from cold. Thin porous coverings 

 moderate the heat of the sun, equalize evaporation and afford great 

 protection in hot climates. In excessive cold, clothing moderates the 

 loss of heat from the surface. When the body is not exposed to 

 currents of air, garments are useful chiefly as non-conductors, impris- 

 oning many layers of air, which are warmed by contact with the 

 person. It is also important to protect the body from the wind, which 

 greatly increases the loss of heat by evaporation. 



When from any cause there is a tendency to undue elevation of the 

 body-heat, cutaneous transpiration is increased and the temperature is 

 kept at the proper standard. This has already been considered in treat- 

 ing of the action of the skin, and facts were noted showing that men 

 can work when exposed to a heat much higher than that of the body 

 itself. The quantity of vapor that is lost under these conditions is some- 

 times very large. Tillet recorded an instance of a young girl who 

 remained in an oven for ten minutes without inconvenience, at a tem- 

 perature of 324.5 Fahr. (162.5 C.). Blagden, in his noted experiments 

 in a heated room, made in connection with Banks, Solander, Fordyce 

 and others, found in one series of observations that a temperature of 

 211 Fahr. (99.5 C.) could be easily borne; and at another time the 

 heat was raised to 260 Fahr. (126.5 C.). Under these external condi- 

 tions, the body is protected from the radiated heat by clothing, the air is 

 perfectly dry, and the animal temperature is kept down by increased 

 evaporation from the surface. 



It is a curious fact that after exposure of the body to an intense dry 

 heat or to a heated vapor, as in Turkish or Russian- baths, when the 

 general temperature is somewhat raised and the surface is bathed in 



