A HISTORY OF SCIENCE 



loss of function, there may be a gradual restoration of 

 the lost function, proving that other centres have 

 acquired the capacity to take the place of the one 

 destroyed. There are limits to this capacity for sub- 

 stitution, however, and with this qualification the 

 definiteness of the localization of motor functions in 

 the cerebral cortex has become an accepted part of 

 brain physiology. 



Nor is such localization confined to motor centres. 

 Later experiments, particularly of Ferrier and of Munck, 

 proved that the centres of vision are equally restricted 

 in their location, this time in the posterior lobes of the 

 brain, and that hearing has likewise its local habitation. 

 Indeed, there is every reason to believe that each form 

 of primary sensation is based on impressions which 

 mainly come to a definitely localized goal in the brain. 

 But all this, be it understood, has no reference to the 

 higher forms of intellection. All experiment has proved 

 futile to localize these functions, except indeed to the 

 extent of corroborating the familiar fact of their de- 

 pendence upon the brain, and, somewhat problemat- 

 ically, upon the anterior lobes of the cerebrum in par- 

 ticular. But this is precisely what should be expected, 

 for the clearer insight into the nature of mental proc- 

 esses makes it plain that in the main these alleged 

 "faculties" are not in themselves localized. Thus, 

 for example, the "faculty" of language is associated 

 irrevocably with centres of vision, of hearing, and of 

 muscular activity, to go no further, and only becomes 

 possible through the association of these widely sep- 

 arated centres. The destruction of Broca's centre, as 

 was early discovered, does not altogether deprive a 



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