oon recognize that the intelligence of an
animal is, in a general manner, proportional to the relative size of
this organ as compared with the sensory ganglia. We are also struck with
the fact that the cerebrum does not send forth to other portions any
independent fibres of its own, nor does it receive any from them, its
only means of communication being through the parts that have been
described--that is to say, through the sensory and automatic apparatus.
[Sidenote: Its relations to the instinctive and automatic portions.] The
cerebrum is therefore a mechanism of a higher order, and its
relationship with the thalami optici and corpora striata indicate the
conditions of its functions. It can only receive impressions which have
come through them, and only act upon the body through their intermedium.
[Sidenote: Its secondary and tertiary lobes.] Moreover, as we ascend the
animal scale, we find that these cerebral parts not only increase in
size, but likewise, in their turn, give rise to offshoots; secondary
lobes emerging posteriorly on the primary ones, and, in due season,
tertiary lobes posteriorly on the secondary. To these, in human anatomy,
the designations of anterior, middle, and posterior lobes have been
respectively given. In proportion, as this development has proceeded,
the intellectual qualities have become more varied and more profound.

[Sidenote: Action of the spinal cord alone.] The relation of the
cerebrum to the cranio-spinal axis is manifested by the circumstance
that the latter can act without the former. In sleep the cerebrum is, as
it were, torpid, but respiration, deglutition, and other reflex actions
go on. If we touch the palm of a sleeping infant our finger is instantly
grasped. [Sidenote: Conjoint action of the brain and cord.] But, though
the axis can work without the cerebrum, the cerebrum can not work
without the axis. Illustrations of these truths may be experimentally
obtained. An animal from which the cerebrum has been purposely removed
may be observed to perform actions automatic and instinctive, but never
intelligent; and that there is no difference between animals and man in
this respect is demonstrated by the numerous instances recorded in the
works of medicine and surgery of injuries by accident or disease to the
human nervous system, the effects corresponding to those artificially
produced in experiments on animals. This important observation,
moreover, shows that we may with correct