THE SKIN, ITS APPENDAGES AND ITS FUNCTION. 45 



needed to eat it. Muscular work is another factor. And 

 finally the whole matter of heat production seems to be 

 under the control of the nervous system. Not much is 

 known on this point except that there is a heat center in 

 the medulla which plays an important part in heat pro- 

 duction and whose influence is seen where the tempera- 

 ture shoots way up in disease just before death. It is 

 now thought that fever is due to a disturbance of this 

 nervous mechanism, though just what the disturbance 

 is is not known. 



Fever is a condition of increased bodily temperature, 

 due to increased production or to decreased loss of heat. 

 As a rule, in all fevers the metabolic changes in the body 

 are increased. Hence the patient becomes emaciated 

 in a long fever. The frequent increase in the amount of 

 urea during fever shows an increase in protein metabo- 

 lism. The temperature in fevers rises as high as 106 

 and in sunstroke sometimes to 110. Except in sun- 

 stroke a higher temperature than 106 generally means 

 death. Subnormal temperature is due to a decrease in 

 the bodily metabolism and so to lessened heat production. 

 As a rule, if the functions are all active, especially that of 

 the sweat glands, a person can be exposed to severe heat 

 without the temperature being affected, though some- 

 times on a hot summer day it may be up half to one 

 degree. The cause of heat-stroke with its high fever is 

 unknown, but probably it is due to some effect on the 

 heat center in the brain. Heat prostration is also due 

 to prolonged exposure to heat, but is generally accom- 

 panied by a subnormal temperature. The effect of cold, 

 as in freezing, is to diminish all the metabolic activities 

 of the body. The temperature can be artificially regu- 

 lated more or less by variations of food, varying amounts 

 of exercise, by drugs, etc. 



Sense of Touch. Before passing on to a discussion of 

 the individual parts, a few words might well be said of the 

 sense of touch, since that is general and resides largely 

 in the skin, whose other functions have just been de- 



