CONTROL OF BOD'S TEMPERATURE AND FEVER 721 



FEVER 



The clinical application of a knowled the mechanism of heal regu- 



lation in the animal body concerns the causes of fever. In the i 

 familiar form fever is produced by infectious p but it may also 



be owing to various other causes, among which may 1"- mentioned I 

 parenteral injection of foreign protein, excessive destruction of prot 

 substances in the body itself, the action of certain drugs, and lastly. 

 injury to the base of the brain or lesions of the upper levels of the spinal 

 cord. Various types of fever are recognized: when the temperature re- 

 mains constantly above the normal, it is known as continuous fever: 

 when oscillations occur bu1 the temperature never falls to the normal 

 level, it is known as remittent; when it attains the normal level at cer- 

 tain periods during the day, it is known as intermittent. 



Causes of Fever 



During a sudden risi in temperature there is, on the one hand, in- 

 creased heat production in t lie muscles, and on the other, dimin- 

 ished heat loss from the surface of the body. Tht fever is therefore 

 due to an exaggeration of the processes b]i which the body normally re- 

 acts to conditions which tend tolowerthi body temperature. Theincreat 

 muscular activity thus induced often causes visible contractions, familiar 

 as shivering; and the constriction of the cutaneous blood vessels pro- 

 duces t he subjective sensation of chills, and causes the skin to 1 me 



pale and cold to t lie touch. The skin muscles also contract, producing 

 "goose skin." During this Btage, objective demonstration of the cur- 

 tailment of the skin circulation can be secured by observation of the 

 bloodnow through the hands and feel page 283). When the temperature 

 suddenly falls again, the crisis, as it is called, muscles become flac 

 and produce less heat, and the cutaneous blood vessels dilate, as has 

 been shown by measurements of the bloodflow of the hands and ;• 

 At the same time also, the sweal glands are stimulated and marked ; 

 Bpiral ion occurs. 



Concerning tin causi oj continuous fever, it most be assumed that I 



balance between heat production and heat loss has been adjusted at a 

 higher plane than normal. \Y- can m>t explain the fever on th< 

 either thai heat production is permanently increased or that heat 

 is permanently diminished, for in neither of these cases would the tem- 

 perature stand at a permanent level but would steadily rise or fall, ac- 

 cording to which mechanism was disturbed. While this higher 

 plane of fever, the thermogenic nerve'eenters are still capable of re- 

 sponding in the usual way to the influences which cause the body tern- 



