90 OF STIMULUS AND EXERTION. SECT. XII. 4. 



IV. Of Stimulus greater than natural. 



i. A quantity of ftimulus greater than natural, 

 producing an increafed exertion of fenforial power, 

 whether that exertion be in the mode of irritation, 

 fenfation, volition, or affociation, diminiflies the 

 general quantity of it. This fact is obfervable in 

 the progrefs of intoxication, as the increafed quan- 

 tity or energy of the irritative motions, owing to 

 the ftimulus of vinous fpirit, introduces much plea- 

 furable fenfation into the fyftem, and much exertion 

 of mufcular or fenfual motions in confequence of this 

 increafed fenfation ; the voluntary motions, and 

 even the aflbciate ones, become much impaired or 

 diminimed ; and delirium and Daggering fucceed. 

 See Seel. XXI. on Drunkennefs. And hence the 

 great proftration of the ftrength of the locomotive 

 mufcles in fome fevers, is owing to the exhauftion 

 of fenforial power by the increafed aftion of the 

 arterial fyftem. 



In like manner a ftimulus greater than natural, 

 applied to a part of the fyftem, increafes the exer- 

 tion of fenforial power in that part, and diminifhes 

 it in fome other part. As in the commencement 

 of fcarlet fever, it is ufual to fee great rednefs and 

 heat on the faces and breafts of children, while at 

 the fame time their feet are colder than natural ; 

 partial heats are obfervable in other fevers with de- 

 bility, and are generally attended with torpor or 

 quiefcence of fome other part of the fyftem. But 

 thefe partial exertions of fenforial power are fome- 

 times attended with increafed partial exertions in 

 other parts of the fyftem, which fympathzie with 

 them, as the flufhing of the face after a full meal. 

 Both thefe therefore are to be afcribed to fympa- 

 thetic aflbciations, explained in Seel, XXXV. and 



not 



