Sect. XII. 2. 4. AND EXERTION. S7 



the fyftem by the violent contractions of the fibres, that inflam- 

 mation arifes, which prevents future cold fits by expending a 

 part of the fenforial power in the extenfion of old vefTels or the 

 production of new ones ; and thus preventing the too great ac- 

 cumulation or exertion of it in other parts of the fyftem 5 or 

 which by the great increafe of ftimulus excites into great action 

 the whole glandular fyftem as well as the arterial, and thence a 

 greater quantity of fenforial power is produced in the brain, and 

 thus its exhauftion in any peculiar part of the fyftem ceafes to be 

 effected. 



4. Or thirdly, in confequence of the painful or pleafurabie 

 fenfation above mentioned, defire and averfion are introduced, 

 and inordinate volition fucceeds ; which by its own exertions 

 expends fo much of the fpirit of animation, that the two other 

 fenforial faculties, or irritation and fenfation, act fo much more 

 feebly ; that the paroxyfms of fever, or that libration between 

 the extremes of exertion and inactivity of the arterial fyftem, 

 gradually fubfides. On this account a temporary infanity is a 

 favourable fign in fevers, as I have had fome opportunities of 

 obferving. 



III. Of repeated Stimulus, 



1. When a ftimulus is repeated more frequently than the ex- 

 penditure of fenforial power can be renewed in the acting or- 

 gan, the effect of the ftimulus becomes gradually diminifhed. 

 Thus if two grains of opium be fwallowed by a perfon unufed 

 to fo ftrong a ftimulus, all the vafcular fyftems in the body act 

 with great energy, all the fecretions and the abforption from 

 thofe fecreted fluids are increafed in quantity \ and pleafure or 

 pain are introduced into the fyftem, which adds an additional 

 ftimulus to that already too great. After fome hours the fenfo- 

 rial power becomes diminifhed in quantity, expended by the 

 great activity of the fyftem 5 and thence, when the ftimulus of 

 the opium is withdrawn, the fibres will not obey their ufual de- 

 gree of natural ftimulus, and a confequent torpor or quiefcence 

 fucceeds, as is experienced by drunkards, who on the day after 

 a great excefs of fpirituous potation feel indigeftion, head-ache, 

 and general debility. 



In this fit of torpor or quiefcence of a part or of the whole 

 of the fyftem, an accumulation of the fenforial power in the af- 

 fected fibres is formed, and occafions a fecond paroxyfm of ex- 

 ertion by the application only of the natural ftimulus, and thus 

 a libration of the fenforial exertion between one excefs and the 

 ether continues for two or three days, where the ftimulus was 



Vol. I. I violent; 



