4 1 9 PISE ASES CLASS IV. 2. 3. 



ORDO II. 



Decreafed AJJbc'mte Motions. 

 GENUS II. 



Catenated with Senjitive Motions. 



IN this genus the fenforial power of aflbciation is exerted with 

 Jefs energy, and thence the actions produced 'by it are lefs than 

 natural ; and pain is produced in confequence, according to the 

 fifth law of animal caufation, Sect. IV. This pain is generally 

 attended with coldnefs of the affected part, and is feldom fuc- 

 ceeded by inflammation of it. This decreafed action of the 

 ifecondary link of the aflbciated motions, belonging to this ge- 

 nus, is owing to the previous exhauftion of fenlbrial power either 

 in the increafed actions of the primary link of the aflbciated mo- 

 tions, or by the pain which attends them ; both which are fre- 

 quently the confequence of the ftimulus of fomething external 

 to the affected fibres. 



As pain is produced either by exrefs or defect of the natural 

 exertions of the fibres, it is not, confidered feparately, a criteri- 

 on of the prefence of either. In the aflbciations belonging to 

 this genus the fenfation of pain or pleafure produces or attends 

 the primary link of the affociated motions, and very often gives 

 name to the difeafe. 



When great pain exifts without caufing any fibrous motions, 

 I conjecture that it contributes to exhauft or expend the gen- 

 eral quantity of fenforial power ; becaufe people are fatigued 

 by enduring pain, till at length they fleep. Which is contrary 

 to what I had perhaps erroneoufly fuppofed in Sect. XXXV. 

 2. 3. If it caufes fibrous motions, it then takes the name of 

 fenfation, according to the definition of fenfation in Sect. II. 2. 

 9. ; and increafed fibrous action or inflammation is the confe- 

 quence. This circumftance of the general exhauftion of fenfo- 

 rial power by the exiftence of pain will afiift in explaining ma- 

 ny of the dileafes of this genus. 



Many of the canals of the body, as the urethra, the bile-duct, 

 the throat, have the motions of their two extremities affociated 

 by having been accuftomed to feel pleafurable or painful fenfa- 

 tions at the fame time or in fucceffion. This is termed fenfi- 

 tive aflbciation, though thofe painful or pleafurable fenfations 

 do not caufe the motions, but only attend them ; and are thus 

 perhaps, ftrictly fpeaking, only catenated with them. 



SPECIES. 



