598 



A MANUAL OF PHYSTOLOGY 



antipyrin, and the group of antipyretics to which it belongs, is 

 the increase in the heat-loss which they bring about by the 

 dilatation of the bloodvessels of the skin. This effect is also 

 produced through the nervous system. 



Fever is a condition so interesting from a physiological point 

 of view, and of such importance in practical medicine, that it 

 will be well to consider a little more closely the possible ways 

 in which a rise of temperature may occur. It must not be for- 

 gotten that the febrile increase of temperature is always accom- 

 panied by other departures 

 from the normal, and that 

 all the fundamental febrile 

 changes may even, in cer- 

 tain cases, be present with- 

 out elevation, and even 

 with diminution of tem- 

 perature. But here we 

 have only to do with the 

 disturbance of the normal 

 equilibrium between the 

 loss and the production of 

 heat ; and it is evident that 

 any of the five conditions 

 illustrated in the diagram 

 (Fig. 199) may give rise to 

 an increase of temperature. 

 It is not necessary to dis- 

 cuss whether cases of fever 

 can actually be found to 

 illustrate every one of 

 these possibilities. It is 

 probable that not infre- 

 quently diminished loss and 

 FIG. 199. DIAGRAM TO SHOW THE POSSIBLE . 



RELATIONS BETWEEN HEAT-PRODUCTION increased production may 



AND HEAT-LOSS IN FEVER. be both involved ; and it 



ought to be remembered 



that the healthy standard with which the heat-production of a 

 fever patient should be compared is not that of a man doing hard 

 work on a full diet, but that of a healthy person in bed, and on 

 the meagre fare of the sick-room. When this is kept in view, 

 the comparatively low heat-production and respiratory exchange 

 which have sometimes been found in fever cease to excite sur- 

 prise. But in any case, no mere change in the relative propor- 

 tions of heat formed and lost is sufficient to explain the febrile 

 rise of temperature. That an increase in heat-production is not 

 of itself enough to produce fever is proved by the fact that severe 



