198 ANATOMY FOR NUESES. [CHAP. XVII. 



packs ; how we recognize the first signs of restored function 

 the moist, warm sweat in the palm of the hand as a pretty 

 sure sign that the fever is " broken." If a very high tempera- 

 ture persists for any length of time, the metabolism of the 

 tissues goes on at such a rapid rate that the capital of the body 

 is soon exhausted. Every organ works with feverish activity, 

 the heart and lungs increase their action, the pulse and respira- 

 tion become more and more hurried, and consequently more and 

 more feeble, until finally, unless relief is obtained, the patient 

 dies of exhaustion. 



In exposure to variations of external temperature, the skin is 

 also the chief agent in regulating the heat of the body. Expos- 

 ure to cold causes the blood-vessels in the skin to contract, the 

 cold acting as a stimulus to the vaso-motor nerves, which con- 

 trol the calibre of the cutaneous blood-vessels. As a result, 

 less blood is sent to the surface to be cooled, and the average 

 blood-temperature is maintained. On the other hand, exposure 

 to warmth causes the cutaneous blood-vessels to dilate, and 

 more blood is sent to the surface to be cooled. Briefly, when 

 the external temperature is high, the cutaneous blood-vessels 

 dilate, and the sweat is also usually poured out upon the sur- 

 face of the skin ; when the external temperature is low, the cuta- 

 neous blood-vessels contract, and the skin usually remains dry. 



By clothing we can aid the functions of the skin and the 

 maintenance of heat ; though, of course, clothes are not in them- 

 selves sources of heat. The object of clothing is, in winter, to 

 prevent conduction, radiation, and evaporation of heat from the 

 skin, and, in summer, to promote it. Of the materials used for 

 clothes, linen is a good conductor ; calico or muslin not quite so 

 good, while wool, silk, and fur are all bad conductors. 



Subnormal temperature. In some maladies the temperature 

 falls distinctly below the normal. This is no doubt chiefly due 

 to diminished metabolism. In cases of starvation, the fall of 

 temperature is very marked, especially during the last days of 

 life. The diminished activity of the tissues first affects the 

 central nervous system ; the patient becomes languid and 

 drowsy, and finally unconscious ; the heart beats more and 

 more feebly, the breath comes more and more slowly, and the 

 sleep of unconsciousness passes insensibly into the sleep of 

 death. 



