THE CEREBRUM, AND ITS FUNCTIONS. 703 



the proefrontal convolution, where it leads downwards and outwards ; that 

 for flexion of the head with rotation towards the side of the stimulus is in a 

 part of the convolution situated still farther towards the front and down- 

 ward, so as to be invisible in a view of the brain taken from above. The 

 centre for the facial muscles is in a region situated on the lateral part of the 

 hemisphere immediately about the supra-Sylviau fissure. 1 The effects of the 

 entire removal of the Cerebral Hemispheres have been already stated ( 

 524). So far as any inferences can be safely drawn from them, these fully 

 bear out the conclusion that the Cerebrum is the organ of Intelligence; 

 since the animals which have suffered this mutilation appear to be constantly 

 plunged in a profound sleep from which no irritation ever seems able to 

 rouse them into full activity, although they give manifestations of conscious- 

 ness. It would be wrong hence to infer, however, as some have done, that 

 such would be the natural condition of an animal without a Cerebrum ; 

 since it is obvious that much of the disturbance of the seusorial powers 

 which is occasioned by this operation, is fairly attributable to the laying 

 open of the cranial cavity, to the disturbance of the normal vascular pres- 

 sure, and to the injury necessarily done to the parts which are left, by their 

 severance from the Cerebrum. Hence the persistence of consciousness after 

 the entire removal of the Cerebrum, which proves that the Cerebrum is 

 not its seat, or at least not its exclusive seat, is a far more important fact 

 than the positive destruction of psychical power which is consequent upon 

 the operation. So far as they can be trusted, however, the results of such 

 mutilations bear out the views already put forth, as to the superadded and 

 non-essential character of the Cerebrum; and justify us in applying to the 

 higher animals the inferences to which we should be led by the contempla- 

 tion of those forms of the nervous system in which no Cerebrum exists. 

 There is nothing, therefore, to oppose the conclusion, that whilst sensations 

 may be felt, and sensori-motor actions excited, independently of the Cere- 

 brum, 2 the presence of this organ is essential to the formation of ideas or 

 notions respecting the objects of sense, and to the performance of those 

 psychical operations for which ideas furnish at once the material and the 

 stimulus to activity. 



568. The information afforded by Pathological phenomena is far from 

 being definite. 3 Many instances are on record in which extensive disease 

 has occurred in one Hemisphere, so as almost entirely to destroy it, without 

 either any obvious injury to the mental powers, or any interruption of the 

 influence of the mind upon the body. But there is no case on record of any 

 such severe lesion of both hemispheres, in which morbid phenomena were 

 not evident during life. It is true that, in Chronic Hydrocephalus, a very 

 remarkable alteration in the condition of the Brain sometimes presents itself 

 which might a priori have been supposed destructive to its power of activity ; 

 the ventricles being so enormously distended with fluid, that the cerebral 

 matter has seemed Tike a thin lamina spread over the interior of the enlarged 

 cranium. But there is no proof that absolute destruction of any part was thus 

 occasioned : and it would seem that the very gradual nature of the change 

 gives to the structure time for accommodating itself to it. This, in fact, is 



1 For other recent researches on this subject see Beaunis, Gazette Medicale de 

 Paris, No. 30, 1872 ; Fournie, Recherches Expe~rimentales, 1873; Criehton Brown, 

 Brit. Med. Juurn., 1875, p. 447. 



2 It is worthy of remark, that M. Flotirens, who in the first instance maintained 

 that sensation is altogether destroyed by the removal of the Cerebrum, has substituted, 

 in the Second Edition of his Researches, the word perception for sensation; appar- 

 ently implying exactly what is maintained above. 



3 For abundant evidence on this point see M. Brown-Sequard, Archives of Scient. 

 and Pract. Med., vol. i, 1873, p. 255. 



