Page:Principles of Psychology (1890) v1.djvu/81

 less differentiated the functions of the several brain-parts seem to be. It may be that the region in question still represents in ourselves something like this primitive condition, and that the surrounding parts, in adapting themselves more and more to specialized and narrow functions, have left it as a sort of through which they send currents and converse. That it should be connected with musculo-cutaneous feeling is, however, no reason why the motor zone proper should not be so connected too. And the cases of paralysis from the motor zone with no accompanying anaesthesia may be explicable without denying all sensory function to that region. For, as my colleague Dr. James Putnam informs me, sensibility is always harder to kill than motility, even where we know for a certainty that the lesion affects tracts that are both sensory and motor. Persons whose hand is paralyzed in its movements from compression of arm-nerves during sleep, still feel with their fingers; and they may still feel in their feet when their legs are paralyzed by bruising of the spinal cord. In a simi- lar way, the motor cortex might be sensitive as well as motor, and yet by this greater subtlety (or whatever the peculiarity may be) in the sensory currents, the sensibility might survive an amount of injury there by which the motility was destroyed. Nothnagel considers that there are grounds for supposing the muscular sense to be exclusively connected with the parietal lobe and not with the motor zone." Disease of this lobe gives pure ataxy without palsy, and of the motor zone pure palsy without loss of muscular sense." He fails, however, to convince more competent critics than the present writer, so I conclude with them that as yet we have no decisive grounds for locating muscular and cutaneous feeling apart. Much still remains to be learned about the relations between musculo-cutaneous sensibility and the cortex, but one thing is certain: that neither the occipital, the forward frontal, nor the temporal lobes seem to have anything essential to do with it in man.