Sect. XII. 2. 1. AND EXERTION. $3 



and the quantity of fenforial power, or fpirit of animation, re- 

 dding in the contracting fibres. Where both thefe quantities 

 are vxz2.t,J}nngth is produced, when that word is applied to the 

 motions of animal bodies. Where either of them is deficient, 

 nveaknefs is produced, as applied to the motions of animal bodies. 



Now as the fenforial power, or fpirit of animation, is perpet- 

 ually exhaufted by the expenditure of it in fibrous contractions, 

 and is perpetually renewed by the fecretion or production of it 

 in the brain and fpinal marrow, the quantity of animal ftrength 

 muft be in a perpetual ftate of fluctuation on this account ; and 

 if to this be added the unceafmg variation of all the four kinds 

 of ftimulus above defcribed, which produce the exertions of the 

 fenforial powers, the ceafelefs viciflitude of animal ftrength be- 

 comes eafily comprehended. 



If the quantity of fenforial power remains the fame, and the 

 quantity of ftimulus be leflened, a weaknefs of the fibrous con- 

 tractions enfues, which may be denominated debility from defecl 

 of ftimulus* If the quantity of ftimulus remains the fame, and 

 the quantity of fenforial power be leffened, another kind of 

 weaknefs enfues, which may be termed debility from defecl of fen- 

 forial power ; the former of thefe is called by Dr. Brown, in 

 his Elements of Medicine, direct debility, and the latter indi- 

 rect debility. The coincidence of fome parts of this work with 

 correfpondent deductions in the Brunonian Elementa Medi- 

 cinal, a work (with fome exceptions) of great genius, muft be 

 confidered as confirmations of the truth of the theory, as they 

 were probably arrived at by different trains of reafoning; 



Thus in thofe who have been expofed to cold and hunper 

 there is a deficiency of ftimulus. While in nervous fever there 

 is a deficiency of fenforial power. And in habitual drunkards, 

 in a morning before their ufual potation, there is a deficiency 

 both of ftimulus and of fenforial power. While, on the other 

 hand, in the beginning of intoxication there is an excefs of ftim- 

 ulus ; in the hot-ach, after the hands have been immerfed in 

 fnow there is a redundancy of fenforial power ; and in inflam- 

 matory difeafes with arterial ftrength, there is an excefs of both. 



Hence if the fenforial power be leflened, while the quantity 

 of ftimulus remains the fame, as in nervous fever, the frequen- 

 cy of repetition of the arterial contractions may continue, but 

 their force in refpect to removing obitacles, as m promoting the 

 circulation of the blood, or the velocity of each contraction, 

 will be diminiihed, that is, the animal ftrength will be leflened. 

 And fecondly, if the quantity of fenforial power b^leflened, and 

 the ftimulus be increafed to a certain degree, as in giving opium 



a in 



