t preserves a uniform exterior, the interior often undergoes
remarkable changes. Convolutions that are frequently called into
action become better supplied with arterial blood, expand and grow,
while the adjacent portion of the inner plate of the skull becomes
absorbed, and presents a remarkable indentation. Convolutions that are
seldom in action shrink in size, and the adjacent bone grows in upon
them. Thus the skull becomes thinner at the site of every active
organ, and thicker over every convolution that is inactive. The
translucency or opacity of the different parts of the skull, when a
light is placed in its interior, generally indicates the active and
inactive organs. Hence, many skulls of fine exterior reveal, upon
interior examination, a degenerate character. Criminal heads generally
present remarkable opacity and thickness in the region of the moral
organs, with distinct digital impressions from the convolutions of the
lower organs.

Thus all craniological observations are liable to inaccuracy, even as
regards development, and much more in regard to functional power. The
activity, power and predominance of an organ may be essentially
changed, without making any perceptible impression upon the interior
of the skull, for an indefinite period. Changes in excitement and
circulation, that revolutionize the character, may leave but a slight
impression upon the interior, and none upon the exterior of the
cranium. The external configuration of the skull is therefore not a
true criterion of character when the influences of education, society,
food, drink and disease have greatly changed the natural bias,
although reliable in a strictly normal condition of brain and cranium.

Organs which easily expand laterally by encroachment upon their
neighbors, which is a common effect of local excitement, must be slow
to make any impression upon the superjacent bone of the cranium.
Cranioscopy, moreover, is incompetent to indicate the development of
small regions or portions of a convolution; it gives but a rude survey
of development. Being thus incapable of minuteness, accuracy and
certainty, it cannot be considered a proper and sufficient basis for
cerebral science. In the hands of Gall and Spurzheim, it had already
very nearly attained its limits as regards the subdivision of organs,
and the progress of their followers in discovery has been unimportant
or fallacious.

To what, then, can we resort, when the failures of Patholo