Sect. XII. OF STIMULUS, Sec. 43 



SECT. XII. 



OF STIMULUS, SENSORIAL EXERTION, AND FIBROUS CONTRAC- 

 TION. 



I. Of fibrous contraction. I. Two particles of a fibre cannot 

 approach without the intervention offomething, as in magnetifm, 

 electricity >, elaflicity. Spirit of life is not electric ether. Galvams 

 experiments. 2. Contraction of a fibre. 3. Relaxation fuc- 

 ceeds. 4. Succeffive contractions , with intervals. Quick pnlfe 

 ■ from debility , from paucity of blood. Weak contractions perform- 

 ed in lefs time, and with fhorter intervals. 5. Lafil filia- 

 tion of the fibres continues after contraclion. 6. Contraclion 

 greater them ufual induces pleafure or pain. 7. Mobility of the 

 fibres uniform. Quantity oj fenforial power fiutluates. Confii- 

 tutes excitability. IL Of fenforial exertion. 1. Animal motion 

 includes ftimulus, fenforial power, and contractile fibres. The fen- 

 forial faculties act feparately or conjointly. Stimulus of four kinds. 

 Strength and weaknefs defined. Senforial power perpetually ex- 

 haufied and renewed. Weaknefs from defecl offiimulus. From 

 defect of fenforial power, the direct and indirect debility of Dr. 

 Brown. Why we become warm in Buxton bath after a time, and 

 fee well after a time in a darkifh room. Fibres may act violently, 

 or with their whole force, and yet feebly. Great exertion in in- 

 flammation explained. Great mufcular force of fome infane peo- 

 ple. 1. Qccafional accumulation of fenforial power in mufcles fub~ 

 Ject to confiant flimulus . In animals jleeping in winter. In eggs, 

 feeds 9 fcirrhous tumours, tendons, bones. 3. Great exertion in- 

 troduces pleafure or pain. Inflammation. Libration of the fyf- 

 iem between torpor and activity. Fever-fits. 4. Defire and a- 

 verfion introduced. Excefs of volition cures fevers. III. Of re- 

 peated ftimulus. I. A flimulus repeated too frequently lofes ef- 

 fect. As opium, wine, grief. Hence old age. Opium and aloes 

 infmalldofes. 2. A flimulus not repeated too frequently does not 

 lofe effect. Perpetual movement of the vital organs. 3. Afilim- 

 ttlus repeated at uniform times produces greater effect. Irrita- 

 tion combined with ajfeiation. 4. A flimulus repeated frequent- 

 ly and uniformly may be withdrawn, and the action of the organ 

 will continue. Hence the bark cures agues ^ and Jlrengthens weak 

 confiitutions. 5 . Defecl offiimulus repeated at certain intervals 

 canjes fever-fits. 6 Stimulus long applied ceafes to acl a fecond 

 time. 7. If a flimulus excites fenfation in an organ not ufua'ly 

 excited into fejifation, inflammation is produced. IV. Of ftimu- 

 lus greater than natural. I. A flimulus greater than natural 



dimimlhes 



