SUP. I., r. 2. THEORY OF FEVER. 459 



different from that which occurs in sleep; as in that the move- 

 ments of the arterial system are increased in energy though not 

 in frequency. Next, the motions of the alimentary canal be- 

 come performed with less energy, or cease altogether; and a 

 total want of appetite to solid food occurs, or sickness or a diarr- 

 hoea occasioned by the indigested aliment. Then the absorbent 

 vessels cease to act with their due energy; whence thirst, and 

 pale urine, though in small quantities. Fourthly, the secerning 

 vessels become affected by the general diminution of sensorial 

 power; whence all the secreted fluids are produced in less 

 quantity. And lastly, the sanguiferous canals feel the general 

 torpor; the pulsations of the heart and arteries become feeble, 

 and consequently quick; and the capillaries of the skin become 

 inactive, acquire less blood from the arteries, and are conse- 

 quently paler and shrunk. 



In this last circumstance of the torpor of the sanguiferous sys- 

 tem consists inirritative fever; as all the others are rather acci- 

 dental or concomitant symptoms, and not essential ones; as fewer 

 or more of them may be present, or may exist with a greater or 

 less degree of inactivity. 



2. Now as the capillaries of the skin are exposed to greater 

 varieties of heat and cold, than the heart and arteries, they are 

 supposed to be more mobile, that is, more susceptible of torpor 

 or exertion, or to inflammation, by external stimuli or influences, 

 than the other parts of the sanguiferous system; and as the skin 

 is more sensible to the presence of heat, than the internal parts 

 of the body, the commencement of the cold paroxysms of lever 

 generally either first exists in, or is first perceived by the cold- 

 ness and paleness of the skin; and the commencement of the hot 

 fits by the heat and redness of it. 



3. The accumulation of sensorial power occurs in these or- 

 gans soonest, and in greatest quantity, during their quiescence, 

 which were most perpetually in action during health; hence 

 those parts of the system soonest recover from torpor in inter- 

 mittent fever, and soonest fall into the contrary extreme of in- 

 creased activity; as the sanguiferous system of the heart and ar- 

 teries and capillaries. But of these the capillaries seem first to 

 acquire a renovation of their action, as the heat of the skin be- 

 comes first renewed, as well as increased beyond its natural 

 quantity, and this in some parts sooner than in others; which 

 quantity of heat is however not to be estimated simply by the 

 rise of the mercury in the thermometer, but also by the quantity 

 carried away into the atmosphere, or diffused amongst other 

 bodies in a given time; as more heat passes through water, 

 which boils vehemently, than when it boils gently, though the 



