544 THE HUMAN BODY 



Fever. The condition of fever or pyrexia, as an abnormally 

 high temperature is named, could conceivably be brought about 

 by increased heat production, decreased heat loss, or both; or by 

 a greater increase of production than of loss. Direct experiments 

 on animals prove that there is always increased production of 

 heat, in febrile diseases. This is shown by the fact that the animal 

 uses more oxygen and gives off more carbon dioxid in a given time 

 than when in health. It also usually gives off more heat, but not 

 enough to compensate for the increase of oxidative processes going 

 on in its body, and so its temperature rises. The regulating mech- 

 anism which in health keeps heat production and heat dissipa- 

 tion proportionate is out of gear. The increased heat production 

 during fever is usually attributed to stimulation of the oxidative 

 processes of the Body by toxins in the blood, but the mechanism 

 of their action is not known. It has been suggested that fever is 

 a protective reaction in that it raises the body temperature above 

 that which is most favorable to the growth of the invading or- 

 ganisms, while at the same time favoring the development of the 

 resisting mechanism of the Body itself. 



Clothing. While the majority of other warm-blooded animals 

 have coats of their own, formed of hairs or feathers, over most of 

 man's Body his hairy coating is merely rudimentary and has lost 

 nearly all physiological importance as a protection from cold; ex- 

 cept in tropical regions he has to protect himself by artificial gar- 

 ments, which his esthetic sense has led him to utilize also for pur- 

 poses of adornment. Here, however, we must confine ourselves 

 to clothes from a physiological point of view. In civilized societies 

 every one is required to cover most of his Body with something, 

 and the question is what is the best covering; the answer will vary, 

 of course, with the climatic conditions of the country dwelt in. 

 In warm countries, clothing, in general terms, should allow free 

 radiation or conduction of heat from the surface; in cold it should 

 do the reverse; and in temperate climates, with varying temper- 

 atures, it should vary with the season. If the surface of the 

 Body be exposed so that currents of air can freely traverse it 

 much more heat will be carried off (under those usual conditions 

 in which the air is cooler than the skin) than if a stationary layer 

 of air be maintained in contact with the surface. As every one 

 knows, a " draught" cools much faster than air of the same tern- 



