EFFECT OF SENSORY STIMULI.--No doubt if we could examine the brain of a
person who has grown up in an environment rich in stimuli to the eye,
where nature, earth, and sky have presented a changing panorama of color
and form to attract the eye; where all the sounds of nature, from the
chirp of the insect to the roar of the waves and the murmur of the
breeze, and from the softest tones of the voice to the mightiest sweep
of the great orchestra, have challenged the ear; where many and varied
odors and perfumes have assailed the nostrils; where a great range of
tastes have tempted the palate; where many varieties of touch and
temperature sensations have been experienced--no doubt if we could
examine such a brain we should find the sensory areas of the cortex
excelling in thickness because its cells were well developed and full
sized from the currents which had been pouring into them from the
outside world. On the other hand, if we could examine a cortex which had
lacked any one of these stimuli, we should find some area in it
undeveloped because of this deficiency. Its owner therefore possesses
but the fraction of a brain, and would in a corresponding degree find
his mind incomplete.
