SICT. XII. 2. OF STIMULUS AND EXERTION. 79 



rary weaknefs of the affefted fibres is induced, till 

 an accumulation of fenibrial power gradually fuc- 

 ceeds, and counterbalances the deficiency of ftimu- 

 lus, and then the bath ceafes to feel cold, and the 

 room ceafes to appear dark ; becaufe the fibres of 

 the fubcutaneous vefiels, or of the organs, of fenfe, 

 act with their ufual energy. 



A fet of mufcular fibres may thus be ftimulated 

 into violent exertion, that is, they may act fre- 

 quently, and with their whole fenforial power, but 

 may ne vert helefs not aft ftrongly ; becaufe the quan- 

 tity of their fenforial power was originally fmall, 

 or was previoufly exhaufted. Hence a ftimulus 

 may be great, and the irritation in confequence act 

 with its full force, as in the hot paroxyfms of ner- 

 vous fever ; but >f the fenforial power, termed irri- 

 tation, be fmall in quantity, the force of the fibrous 

 contractions, and the times of their continuance in 

 their contracted ftate, will be proportionally fmall. 

 In the fame manner in the hot paroxyfm of- 

 putrid fevers, which are (hewn in Se<5t. XXXI-II. to 

 be inflammatory fevers with arterial debility, the 

 fenforial power termed fen fat ion is exerted with 

 great activity, yet the fibrous contractions, which 

 produce the circulation of the blood, are perform- 

 ed without ftrength, becaufe the quantity of fenfo- 

 rial power then refiding in that part of the fyftem is 

 fmall. 



Thus in irritative fever with arterial ftrength, 

 that is, with excefs of fpirit of ani mation, the quan- 

 tity of exertion during the hot part of the paroxyfrn 

 is to be eftirnated from the quantity of ftimulus, 

 and the quantity of fenforial power. While in fen- 

 fitive (or inflammatory) fever with arterial ftrength, 

 that is, with excefs of fpirit of animation, the 

 violent and forcible actions of the vafcular fyftem 

 during the hot part of the paroxyfm are induced by 

 the exertions of two fenibrial powers, which are 



excited 



