348 DISEASES SECT. XXXV. 2. r, 



with greaf-er violence in the fame place ; and, before I could ar- 

 rive, as fhe lived 30 miles from me, (he fuffered a paralytic 

 ftroke ; which affefted her limbs and her face on one fide, and 

 relieved the pain of her head. 



About a year afterwards I was again called to her on account 

 of a pain, as violent as before, exactly on the fame part of the 

 other parietal bone. On examining her mouth I found the fecond 

 molaris of the under jaw on the fide before affe&ed was now- 

 decayed, and concluded that this tooth had occafioned the ftroke 

 of the palfy by the pain and confequent exertion it had caufed. 

 On this account I earneftly entreated her to allow the found mo- 

 laris of the fame jaw oppofite to the decayed one to be extraft- 

 ed ; which was forthwith done, and the pain of her head im- 

 mediately ceafed, to the aftonifhment of her attendants. 



In the cafes above related of the pain exifting in a part dif- 

 tant from the feat of the difeafe, the pain is owing to defel of 

 the ufual motions of the painful part. This appears from the 

 coldnefs, palenefs, and emptinefs of the affetted veffels, or of 

 the extremities of the body in general, and from there being no 

 tendency to inflammation. The increafed aUon of the prima- 

 ry part of thefe aflbciated motions, as of the hepatic termination 

 of the bile-duft from the ftimulus of a gall-ftone, or of the inte- 

 rior termination of the urethra from the ftimulus of a ftone in 

 the bladder, or laftly, of a decaying tooth in hemicrania, de- 

 prives the fecondary part of thefe aflbciated motions, namely, 

 the exterior terminations of the bile-dudl or urethra, or the pain- 

 ed membranes of the head in hemicrania, of their natural fhare 

 of fenforial power : and hence the fecondary parts of thefe fen- 

 fitive trains of affbciation become pained from the deficiency of 

 their ufual motions, which is accompanied with deficiency of 

 fecretions and of heat. See Sett IV. 5. XII. 5. 3. XXXIV. i. 



Why does the pain of the primary part of the aflbciation 

 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 aflbciated trains of motion was ow- 

 ing to too great ftimulus, as of the ftone at the neck of the blad- 

 der, and was confequently caufed by too great adlion *of the 

 pained part. This greater aftion than natural of the primary 

 part of thefe aflbciated motions, by employing or expending the 

 fenforial power of irritation belonging to the whole aflbciated 

 train of motions, occafioned torpor, and confequent pain in 

 the fecondary part of the aflbciated train j which was poflefled 

 of greater fenfibility 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 power of fenfation belonging 



to 



