cerebrum. For instance, a sensory impulse may be carried inward to
the cells of the spinal cord and upward to the cerebellum without any
resulting consciousness. When, however, the stimulus reaches a higher
centre in the cortex of the brain, the mind becomes conscious, or
interprets the impression, and any resulting action will be controlled
by consciousness, through impulses given to the motor nerves. It is for
this reason that the cortex is called the seat of consciousness, and
that mind is said to reside in the brain.

=Localization of Function.=--In addition, however, to placing the seat
of consciousness in the cortex of the brain, psychologists also claim
that different parts of the cortex are involved in different types of
conscious activity. Sensations of sight, for instance, involve certain
centres in the cortex, sensations of sound other centres, the movements
of the organs of speech still other centres. Some go so far as to claim
that each one of the higher intellectual processes, as memory,
imagination, judgment, reasoning, love, anger, etc., involves neural
activity in its own special section of the cortex. There seems no good
evidence, however, to support this view. The fact seems rather that in
all these higher processes, quite numerous centres of the cortex may be
involved. The following figure indicates the main conclusions of the
psychologists in reference to the localization of certain important
functions in distinct areas of the cortex.

[Illustration: REFLEX ACTS]

=Nature of Reflex Action.=--While a lower nerve centre is not a seat for
purposeful consciousness, these centres may, in addition to serving as
transmission points for cortical messages, perform a special function
by immediately receiving sensory impressions and transmitting motor
impulses. A person, for instance, whose mind is occupied with a problem,
may move a limb to relieve a cramp, wink the eye, etc., without any
conscious control of the action. In such a case the sensory impression
was reported to a lower sensory centre, directly carried to a lower
motor centre, and the motor impulse given to perform the movement. In
the same way, after one has acquired the habit of walking, although it
usually requires conscious effort to initiate the movements, yet the
person may continue walking in an almost unconscious manner, his mind
being fully occupied with other matters. Here, also, the complex actions
involved in walking are controlled a