Sup. I. 8. ic. THEORY OF FEVER. 469 



whole lunar period pafles, before it recovers its due irritability 

 and confequent action. 



In fimilar manner, after a perfon has been coniined in a very 

 warm room for fome hours, the cutaneous capillaries, with their 

 fecretory and abforbent vefTels, become exhaufted of their fen fo- 

 rial power of irritation by the too great violent exertions occa- 

 fioned by the unufual ftimulus of heat ; and in coming into a 

 colder atmofphere an inactivity of the cutaneous veiTels exifts at 

 firft for fome time without accumulation of fenforial power ; as 

 is fhewn by the continuance of the pain of cold and the pale- 

 nefs j but after a time both the pain of cold and paleneis van- 

 ifh, which now indicates an accumulation of the fenforial pow- 

 er of irritation, as lefs degrees of heat ftimuiate the fyftem into 

 due action. 



In the fame manner, after any one has been fome time in the 

 fummer funlhine, on coming into a dark cell he continues much 

 longer before he can clearly diftinguifh objects, than if his eyes 

 had only been previoufly expofed to the light of a clcudy day in 

 winter ; becaufe the fenforial power of irritation, and confequent 

 fenfation, had in the firft cafe been previoufly much expended 

 or exhaufted ; and therefore required a much longer time be- 

 fore it could be produced in the brain, or derived to the cptic 

 nerves, in fuch quantity as to reftore the deficiency, and to caufe 

 an accumulation of it ; whereas in the latter cafe no deficiency 

 had occurred. 



10. Thus the accumulation or deficiency of fenforial power 

 in a torpid organ, which had previoufly been accuftomed to per- 

 petual action, depends on the manner in which it becomes tor- 

 pid 5 that is, whether by great previous ftimulus, or great previ- 

 ous excitement of the power of afibciation ; or by defect of its 

 accuftomed ftimulus, or of its accuftomed excitement of the 

 power of afibciation. lathe former cafe the fenforial power is in 

 an exhaufted ftate, and therefore is not likely to become fo foon 

 accumulated, as after drunkennefs, or expofure to great heat, or 

 to great light ; in the latter a great accumulation of fenforial 

 power occurs, as after expofure to cold, or hunger, or darknefs. 



Hence when the ftomach continues toKpid by previous vio- 

 lent ftimulus, as in the exhibition of digitalis, no accumulation 

 of fenforial power of irritation fupervenes \ and in confequence 

 the motions of the heart and arteries, which are aflbciated with 

 thofe of the ftomach, become weak, and flow, and intermittent, 

 from the defect of the excitement of the fenforial power of afib- 

 ciation. But what follows ? as the actions ci the heart and ar- 

 teries are leiTened by the deficient action of the fenforial power 

 of afibciation, and not by previous increafed excitement of it ; 



a 



