SUP. I. 7. 2. THEORY OF FEVER. 459 



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

 ments of the arterial fyftem are increafed in energy though not 

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

 come performed with lefs energy, or ceafe altogether ; and a 

 total want of appetite to folid food occurs, or ficknefs or a diar- 

 rhoea occafioned by the indigefted aliment. Then the abforbent 

 veflels ceafe to adt with their due energy ; whence thirft, and 

 pale urine, though in fmall quantities. Fourthly, the fecerning 

 veflels become affected by the general diminution of f-nforial 

 power ; whence all the fecreted fluids are produced in lefs 

 quantity. And laftly, the fanguiferous canals feel the general 

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

 and confequently quick ; and the capillaries of the (kin become 

 inactive, acquire lefs blood from the arteries, and are confe- 

 quently paler and flirunk. 



In this laft circumftance of the torpor of the fanguiferous 

 fyftem confifts inirritative fever ; as all the others are rather ac- 

 cidental or concomitant fymptoms, and not eflential ones ; as 

 fewer or more of them may be prefent, or may exift with a 

 greater or lefs degree of inactivity. 



2. Now as the capillaries of the fkin are expofed to greater 

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

 fuppofed to be more mobile, that is, more fufceptible of torpor 

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

 than the other parts of the fanguiferous fyftem ; and as the fldn. 

 is more fenfible to the prefence of heat, than the internal parts 

 of the body, the commencement of the cold paroxyfms of fever 

 generally either firft exifts in, or is firft perceived by, the cold- 

 nefs and palenefs of the fkin j and the commencement: of the hot 

 fits by the heat and rednefs of it. 



3. The accumulation of fenforial power occurs in thefe or- 

 gans fooneft, and in greateft quantity, during their quiefcence, 

 which were mofl perpetually in action during health ; hence 

 thofe parts of the fyftem fooneft recover from torpor in inter- 

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

 creafed activity ; as the fanguiferous fyftem of the heart and ar- 

 teries and capillaries. But of thefe the capillaries feem firft to 

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

 comes firft renewed, as well as increafed beyond its natural 

 quantity, and this in fome parts fooner than in others ; whicli 

 quantity of heat is however not to be eftimatcd fimply by the 

 rife of the mercury in the thermometer, but alfo by the quanti- 

 ty carried away into the atmofphere, or diffufed amongft other 

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

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



rife 



