Mrs. ——­, about 30 years of age, was seized with great pain about the middle of the right parietal bone, which had continued a whole day before I saw her, and was so violent as to threaten to occasion convulsions.  Not being able to detect a decaying tooth, or a tender one, by examination with my eye, or by striking them with a tea-spoon, and fearing bad consequences from her tendency to convulsion, I advised her to extract the last tooth of the under-jaw on the affected side; which was done without any good effect.  She was then directed to lose blood, and to take a brisk cathartic; and after that had operated, about 60 drops of laudanum were given her, with large doses of bark; by which the pain was removed.  In about a fortnight she took a cathartic medicine by ill advice, and the pain returned with greater violence in the same place; and, before I could arrive, as she lived 30 miles from me, she suffered a paralytic stroke; which affected her limbs and her face on one side, 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 same part of the other parietal bone.  On examining her mouth I found the second molaris of the under-jaw on the side before affected was now decayed, and concluded, that this tooth had occasioned the stroke of the palsy by the pain and consequent exertion it had caused.  On this account I earnestly entreated her to allow the sound molaris of the same jaw opposite to the decayed one to be extracted; which was forthwith done, and the pain of her head immediately ceased, to the astonishment of her attendants.

In the cases above related of the pain existing in a part distant from the seat of the disease, the pain is owing to defect of the usual motions of the painful part.  This appears from the coldness, paleness, and emptiness of the affected vessels, or of the extremities of the body in general, and from there being no tendency to inflammation.  The increased action of the primary part of these associated motions, as of the hepatic termination of the bile-duct; from the stimulus of a gall-stone, or of the interior termination of the urethra from the stimulus of a stone in the bladder, or lastly, of a decaying tooth in hemicrania, deprives the secondary part of these associated motions, namely, the exterior terminations of the bile-duct or urethra, or the pained membranes of the head in hemicrania, of their natural share of sensorial power:  and hence the secondary parts of these sensitive trains of association become pained from the deficiency of their usual motions, which is accompanied with deficiency of secretions and of heat.  See Sect.  IV. 5.  XII. 5. 3.  XXXIV. 1.