in the cavity at the base of the skull, and the posterior lobe is
supported by the tentorium, by which it is separated from the cerebellum
beneath. One of the most prominent characteristics of the cerebrum is
its many and varied _convolutions_ These do not correspond in all
brains, nor even on the opposite sides of the same brain, yet there are
certain features of similarity in all; accordingly, anatomists enumerate
four _orders of convolutions_. The first order begins at the _substantia
perforata_ and passes upward and around the corpus callosum toward the
posterior margin of that body, thence descends to the base of the brain,
and terminates near its origin. The second order originates from the
first, and subdivides into two convolutions, one of which composes the
exterior margin and superior part of the corresponding hemisphere, while
the other forms the circumference of the _fissure of Sylvius_. The third
order, from six to eight in number, is found in the interior portion of
the brain, and inosculates between the first and second orders. The
fourth is found on the outer surface of the hemisphere, in the space
between the sub-orders of the second clasp. A peculiar fact relating to
these convolutions is observed by all anatomists: mental development is
always accompanied by an increasing dissimilarity between their
proportional size.

The cerebral hemispheres may be injured or lacerated without any pain to
the patient. The effect seems to be one of stupefaction without
sensation or volition. A well-developed brain is a very good indication
of intelligence and mental activity. That the cerebrum is the seat of
the reasoning powers, and all the higher intellectual functions, is
proved by three facts. (1.) If this portion of the brain is removed, it
is followed by the loss of intelligence. (2.) If the human cerebrum is
injured, there is an impairment of the intellectual powers. (3.) In the
animal kingdom, as a rule, intelligence corresponds to the size of the