CHAP, vi.] THE BRAIN. 631 



on to the 'visual area of* the cerebral convolutions. Munk has 

 moreover been led, for reasons which we cannot enter into here, to 

 believe that removal of part of this area (the circumferential part) 

 leads to what may be called 'absolute blindness,' i.e. the inability 

 to gain conscious sensations of the images falling on the retina, 

 whereas removal of another part (the central part) leads to what may 

 be called 'psychical blindness/ i.e. the inability to form an intelligent 

 comprehension of the visual impressions received. The latter, he 

 maintains, may eventually be recovered from by processes which 

 may be crudely spoken of as the deposition of new visual experiences 

 in the visual area. We cannot discuss these results in detail here, 

 but we may add that Munk has similarly been led from his experi- 

 ments to conclude that the rest of the cerebral surface may be 

 parcelled out into auditory, olfactory, tactile, &c. areas, in fact that 

 all the sensory impulses which stream upon the living body are 

 projected as sensations on to the cerebral convolutions in definite 

 order, being there elaborated into perceptions and experiences, this 

 reception and elaboration being the special work of the cerebral 

 cortex. And one author (Schiff) has from the first maintained 

 that the cortical 'motor' areas associated with movements in 

 particular regions of the body, have to do with the tactile 

 sensations arising in those regions, and that the movements 

 arising from stimulation of the areas are tactile reflex actions 

 started in the cortex of the brain instead of in the periphery 

 of the body. 



On the other hand another observer (Goltz) maintains that the 

 whole of the posterior lobes may be removed without affecting 

 vision any more directly than does the removal of the anterior or 

 middle lobes. In fact this author in his latest, as in his earlier 

 researches, insists most strongly that he can no more obtain distinct 

 evidence of localization in reference to vision or other sensations 

 than in reference to movements. When in a dog the lesions are 

 slight the recovery from imperfections of vision, of the other senses, 

 and of general sensibility which follow immediately on the opera- 

 tion, may be complete. When a larger portion of brain is removed, 

 whatever be the region of the hemisphere acted on, certain 

 peculiar imperfections of sight and other sensations, corresponding 

 to the psychical blindness spoken of just now as observed by Munk, 

 become striking, and may remain permanent. In the case of 

 vision the salient character of this imperfection is that though the 

 animal evidently can see, and uses his sight successfully in avoiding 

 obstacles and guiding his movements, yet what he sees does not 

 produce its usual effect on him; he obviously fails to recognize 

 many things, and has become indifferent to scenes which formerly 

 affected him strongly. Thus a dog from which portions of the 

 cerebral hemispheres have been removed, fails to recognize his 

 food by sight; when he is threatened with the whip, he is not 

 cowed; when the hand is held out for his paw he makes no 



