e 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.

Why does the pain of the primary part of the association cease, when that
of the secondary part commences? This is a question of intricacy, but
perhaps not inexplicable. The pain of the primary part of these associated
trains of motion was owing to too great stimulus, as of the stone at the
neck of the bladder, and was consequently caused by too great action of the
pained part. This greater action than natural of the primary part of these
associated motions, by employing or expending the sensorial power of
irritation belonging to the whole associated train of motions, occasioned
torpor, and consequent pain in the secondary part of the associated train;
which was possessed of greater sensibility than the primary