Faculty of Speech and Speech-Centers
The proof that there are material changes in the cell-groups of gray matter which have been educated in language is shown, as we have seen, by the study of injuries to the brains of polyglots who successively acquired several tongues. When the speech-area which governs the mastery of the mother-tongue is injured, the areas cultivated for the other languages may perform their functions without appreciable embarrassment. This proves that there are definite and distinct regions in the nervous substance which have been modified: one for the requirements of one language, and one for those of another. Whether these modifications are wrought in strata or in superficial contiguous zones would be difficult to say. This however is sure: That which is subject to material interference must have some material basis.
So we see that the human brain, in regard to language with which we are now concerned, is capable of a vast increase of function not only, but also of the acquirement
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