ANIMAL HEAT. 521 



ran its course ; and might not this supply, to a certain extent, the abnormal waste of 

 tissue ? 



Equalization of the Animal Temperature. A study of the phenomena of calorification 

 in the human subject has shown that, under all conditions of climate, the general heat of 

 the body is equalized. 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 desira- 

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

 must certainly be regarded as a physiological necessity. Clothing protects from excessive 

 heat as well as from cold. Thin, porous articles moderate the heat of the sun, equalize 

 evaporation, and afford great protection in hot climates. In excessive cold, clothing is 

 of the greatest importance in preventing the escape of heat from the body. When the 

 body is not exposed to currents of air, the garments are useful chiefly as non-conductors, 

 imprisoning many layers of air, which are warmed by contact with the person. It is 

 farther very important to protect the body from the wind, which increases so greatly the 

 loss of heat by evaporation. 



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

 cutaneous transpiration is increased, and the temperature is kept at the proper standard. 

 We have already considered this question in treating of the action of the skin, and we have 

 noted facts showing that men can work when exposed to a heat much higher than that 

 of the body itself. The amount of vapor that is lost under these conditions is sometimes 

 enormous, amounting to from two to four pounds in an hour. We have ourselves often 

 noted a loss of between two and three pounds after exposure for less than an hour in a 

 steam-bath of from 110 to 116; and a much greater elevation of temperature, in dry 

 nir, can be tolerated with impunity. We have alluded to some of the observations upon 

 t : :e temperatures that could be borne without bad results, in connection with the ques- 

 tion of variations in the heat of the body. In the experiments of Delaroche and Berger, 

 the temperature was considerably under 200. Tillet recorded an instance of a young 

 girl who remained in an oven for ten minutes without inconvenience, at a temperature 

 of 130 Reaumur, or 324-5 Fahr. Dr. Blagden, in his noted experiments in a heated 

 room, made in connection with Drs. Banks, Solander, Fordyce, and others, .found, in one 

 series of observations, that a temperature of 211 could be easily borne; and, at another 

 time, the heat was raised to 260. Chabert, who exhibited in this country and in Eu- 

 rope under the name of the " fire-king," is said to have entered ovens at from 400 to 

 600. Under these extraordinary external conditions, the body is protected from the 

 radiated heat by clothing, the air is perfectly dry, and the animal temperature is kept 

 down by excessive 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 the Turkish or Russian baths, when the general temperature is 

 somewhat raised and the surface is bathed in perspiration, a cold plunge, which checks 

 the action of the skin almost immediately, is not injurious and is decidedly agreeable. 

 This presents a striking contrast to the effects of sudden cold upon a system heated and 

 exhausted by long-continued exertion. In the latter instance, when the perspiration is 

 suddenly checked, serious disorders of nutrition, inflammations, etc., are very liable to 

 occur. The explanation of this, as far as we can present any, seems to be the following: 

 When the skin acts to keep down the temperature of the body in simple exposure to 

 external heat, there is no modification in nutrition, and the tendency to an elevation of 

 the animal temperature comes from causes entirely external. It is a practical observa- 

 tion that no bad effects are produced, under these circumstances, by suddenly changing 

 the external conditions ; but, when the animal temperature is raised by a modification 

 of the internal nutritive processes, as in prolonged muscular effort, these changes should 

 not be suddenly arrested ; and a suppression of the compensative action of the skin is 

 apt to produce disturbances in nutrition, very often resulting in inflammations. 



