$IQ DISEASES OF ASSOCIATION. SECT, XXXV. 2. 



and emptinefs of the affe&ed veffels, or of the ex- 

 tremities of the body in general, and from there 

 being no tendency to jcn flam mar ion-. The increafed 

 action of the primary part of thefe aiTociated mo- 

 tions, as of the hepatic termination of the bik-du& 

 from the ftimulus of a gall-ftone, or of the interior 

 termination of die urethra from the ftimulos of a 

 flone in the bladder, or laftlv, of a decaying tooth 

 in hemicrania, deprives the fecondary part of thefe 

 affociated motions, namely, the exterior terminati- 

 ons of the bile-duel or urethra, or the pained mern- 

 fcranes of the head in hemicrania, of their narural 

 fhare of fenforial power : and hence the fecondary 

 parts of thefe fenfttive trains of aiTociation become 

 pained from the deficiency of their ufaal motions, 

 which is accompanied with deficiency of fecretions 

 and of heat. See Sett. IV. 5. XII 5. 3. XXXIV. u 



Why does the pain of the primary part of the 

 affociation ceafe, when that of the fecondary part 

 commences ? This is a queftion of intricacy, but' 

 perhaps not inexplicable. The pain of the primary 

 part of thefe affociated trains of motion was owing 

 to too great fUmutus, as of the flone at the neck of 

 the bladder, and was consequently caufed by too- 

 great a&ion of the pained part. This greater ac- 

 tion than natural of the primary part of thefe affo- 

 eiated motions, by employing or expending the fen- 

 forial power of irritation belonging to the whole 

 affociated train of motions, occafioned torpor, and 

 confequent pain in the fecondary part of the affoci- 

 ated train ; which was poffeffed of greater feniibility 

 than the primary part of it. Now the great pain 

 of the fecondary part of the train, as foon as it 

 commences, employs or expends the fenforial pow- 

 er of fenfation belonging to the whole affociated 

 train of motions ; and in confequence the motions 

 of the primary part, though increafed by the ftimu- 

 lus 



