Faculty of Speech and Speech-Centers
hemispheres. But no speech-area exists in the brain of ape, and it occurs virtually in only one hemisphere of the brain of man. The other hemisphere of the human brain remains as barren as both hemispheres of the ape’s brain. The faculty of speech therefore did not originate in anatomy. Since it exists, its origin must have been phsyiological.
In all right-handed persons, then, it is the left hemisphere of the brain that holds the speech-centers. Words are uttered by means of the left convolution of Broca; they are seen by means of the left angular gyrus; they are heard by means of the left superior temporal convolution. Where they are felt, by the right-handed blind deaf-mute, is not known precisely; but that this center also lies in the left hemisphere there is no doubt.
The bald fact that the left cerebral hemisphere has held the speech-centers of the majority of mankind through its long history would indicate that the left brain differed in some innate respect from its twin, the right.
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