All this accords with the evidence upon which our whole localization theory is based. This evidence tends to show: (1) that the different forms of mental functioning are not absolutely dependent upon definitely circumscribed and permanently fixed portions of the cerebral hemispheres; and (2) that by mental development a relative independence of the particular areas originally connected with the different forms of mental functioning may be attained. From the physiological point of view the cerebral substance appears as plastic and educable to a degree until recently unsuspected. And any dislocation or interruption of the proper connections becomes more dangerous than even a considerable loss of the brain-substance. From another point of view the same conclusion was reached in a paper entitled "A Suggestive Case of Nerve-Anastomosis," which I read before the Psychological Association at its meeting in 1904. I take this opportunity to call attention to the fact that Dr. Gushing by a purposeful division of the facial nerve and its anastomosis with the spino-facial, has more recently succeeded in restoring to the patient a considerable degree of normal emotional control of the expressive muscles of the face. I leave to expert physiologists to conjecture what new adjustments in their related forms of functioning this required from the cerebral hemispheres.
Third, these cases of cerebral surgery without anesthesia would seem further to confirm what has for some time been held to be true —namely, that slow abnormal developments, even when they finally involve much more serious destruction of the cerebral areas, and interruptions of the normal connections, are tolerated much more easily than sudden and rapid lesions or other abnormalities. Nor does it appear wholly out of place to say that while this education of the cerebral hemispheres to unwonted functions requires time, the emotions and will of the conscious agent are factors of the greatest importance in securing the results of this education.
Finally, there is one thought which I bring forward, not as a matter of argument, much less of proof; but, the rather, as a personal impression amounting almost to a conviction. In stating this impression I will take the liberty to employ the language of an "old-fashioned" but by no means altogether discredited psychology. Here is an intelligent human soul; he remains perfectly conscious, free from pain, and taking a lively interest in a surgical operation which explores, incises, pulls about, and otherwise manipulates, and finally drags two large abnormal growths out from, what is known to be the most important part, for the life of conscious sensation and voluntary motion, of his own brain. From the anatomical and physiological
