This is a question which has engaged the attention of experimentalists during the past twelve years. The only positive result arrived at so far has been that in certain animals a circumscribed area at the base of the præfrontal gyrus may be found, which by electric stimulation will cause a closure of the glottis by complete symmetrical adduction of both vocal cords. This effect is obtainable irrespective of the focus stimulated, whether right or left, and regardless of previous extirpation of the opposite corresponding focus. This, then, is a condition wholly different from that which pertains in the cortical centres for facial and other movements, and, as proved by Semon and Horsley, when both centres are extirpated, or even when both cerebral hemispheres are removed, there never ensues any vocal cord paralysis. In animals thus treated the glottis aperture is not at all changed in shape, and the laryngeal functions appear to be fully maintained. The so-called phonation centre cannot thus rank with other motor cortical centres. One investigator, Masini, is said to have discovered a cortex centre which on irritation caused adduction of the opposite vocal cord only—but his result has not been verified by prior observers (Krause, Horsley, Semon, and others) or by later experimenters who have worked to obtain his results (Onodi, Klemperer). The absence of clinical evidence of vocal cord paralysis due to cortical lesion corresponds, too, with the failure artificially to induce unilateral focal action. Klemperer has recently (Archiv. f. Laryng., B. ii., H. 3) corroborated and extended the earlier researches of Krause, Semon, and Horsley. He has not only extirpated the centres to find that the operation had no effect whatever on the mobility of the vocal cords, but even after induced infection of the centres by the injection of typhus bacilli cultures (evoking thus an acute septic irritation) he has found that there was no implication of function whatever. Quite recently, at the last annual meeting of the British Medical Association, Risien Russell contributed a paper in which he demonstrates the actual existence of centres for ab- and adduction of the cords, though he, too, had not been able to produce isolated movements of the opposite vocal cord by stimulation of the corresponding areas in the opposite hemisphere.
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