20, REGULATION OF HEAT. 



set free by the putrefaction of manure in his forcing frames, to bring forth 

 plants in the early spring. There is no kind of decay, or putrefaction, or 

 oxidation of organic matters, however slow it may be, that is not marked 

 by the production of warmth. 



Man, in a state of health, maintains a nearly uniform temperature. 

 Heat of man: Neglecting slight variations, to be hereafter critically exam- 

 its cause. wed, it is 98 degrees. For the most part, it is immaterial 

 in what climate of the earth he may reside, whether in the cold polar re- 

 gions or the hot tropic ; he is so constituted that, either through the pro- 

 visions of his own organization, or by resorting to the adventitious aid of 

 clothing, or to special articles of food, he can maintain himself at about 

 the same degree ; and as all this heat arises from interstitial oxidation 

 continually taking place, it is obvious that within certain limits he has 

 control over it. Thus, in the winter he sometimes resorts to violent mus- 

 cular action in order to increase the rapidity of respiration and the de- 

 struction of muscular tissue ; for the greater the quantity of air intro- 

 duced in a given period of time, the higher the temperature rises, just 

 as when we close the door of a stove, or place a blower on an anthracite 

 fire, an increased draught is occasioned and the quantity of heat is in- 

 creased. To breathe with rapidity and depth is certain to raise the tem- 

 perature. 



On the contrary, in summer, when the heat is oppressive, we instinct- 

 ively abstain from muscular exertion, tranquil and slow respiration goes 

 on, and the temperature is kept down. Again, there are means of occa- 

 sioning an increased liberation of heat by changing the nature of the food 

 and using highly combustible material, such as the various kinds of alco- 

 holic preparations. The chemical constitution of alcohol is such that in 

 the act of burning carbonic acid and water are produced with the libera- 

 tion of so much heat that chemists find it one of the most suitable means 

 of attaining a high temperature. On taking preparations of this substance, 

 such as distilled liquors or wines, the first effect is the production of a 

 genial warmth all over the body, intoxication eventually coming on as a 

 secondary result. 



These remarks are not limited in their application to our own species, 

 the whole animal world furnishes us with commentaries on their truth. 

 Man maintaining a temperature, as has been said, of about 98 degrees, 

 other animals are at other degrees, some being cold-blooded and some hot. 

 The particular point they reach depends, as direct observation shows, on 

 the quantity of oxygen they consume, or, in other words, on their respira- 

 tion. Birds, whose breathing mechanism is by far the most elaborate 

 and extensively developed, have by far the highest temperature. The 

 snake or the tortoise, whose rate of respiration is very slow, and which 

 consume but little oxygen, have a correspondingly low degree of heat. 



