FUNCTIONS OF THE CEREBRUM. 369 



laud and Longet, it was the opinion of the observers, that sensibility was 

 retained, after the complete removal of the Cerebrum ; although the animals 

 appeared unable to attach any ideas to their sensations.* The results of par- 

 tial mutilations are usually, in the first instance, a general disturbance of the 

 Cerebral functions; which subsequently, however, more or less subsides, leav- 

 ing but little apparent affection of the animal functions, except muscular weak- 

 ness. The whole of one Hemisphere has been removed in this way, without 

 any evident consequence, save a temporary feebleness of the limbs on the 

 opposite side of the body, and what was supposed to be a deficiency of sight 

 through the opposite eye. The former was speedily recovered from, and the 

 animal performed all its movements as well as before ; the latter, however, 

 was permanent, but the pupil remained active. When the upper part, only, 

 of both Cerebral Hemispheres was removed by Hertwig, the animal was re- 

 duced, for fifteen days, to nearly the same condition with the one from which 

 they had been altogether withdrawn ; but afterwards, sensibility evidently re- 

 turned, and the muscular power did not appear to be much diminished. 



486. The information afforded by Pathological phenomena is equally far 

 from being definite. Many instances are on record, in which extensive dis- 

 ease 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 severe lesion of both hemispheres, in which morbid phenomena were not 

 evident during life. It is true, that in Chronic Hyclrocephalus, a very remark- 

 able 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 like a thin lamina, spread over the interior of the enlarged cra- 

 nium. 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 

 to be noticed in all diseases of the Encephalon. A sudden lesion, so trifling 

 as to escape observation, unless this be very carefully conducted, will occasion 

 very severe symptoms ; whilst a chronic disease may gradually extend itself, 

 without any external manifestation. It will usually be found that sudden 

 paralysis, of which the seat is in the Brain, results from some slight effusion 

 of blood in the substance or neighbourhood of the Corpora Striata ; whilst, 

 if it follow disorder of the Brain of long standing, a much greater amount of 

 lesion will usually present itself. In either case, the paralysis occurs in the 

 opposite side of the body, as we should expect from the decussation of the 

 pyramids ; but it may occur either in the same, or on the opposite side of the 

 face, the cause of which is not very apparent. If convulsions accompany 

 the paralysis, we may infer that the Corpora Quadrigemina, or the parts below, 

 are involved in the injury ; and in this case it is usually found, that the con- 

 vulsions are on the paralyzed side of the body, the effect of the lesion, both 

 of the Cerebrum and of the Corpora Quadrigemina, being propagated to the 

 opposite side, by the decussation of the Pyramids. Where, as not unfre- 

 quently happens, there is paralysis of one side, accompanying convulsions on 

 the other, it is commonly the result of a lesion affecting the base of the Brain 

 and Medulla Oblongata, on the side on which the convulsions take place ; 

 here the effect of the lesion has to cross from the Brain, whilst its influence 



It is worthy of remark, also, that M. Flourens, 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 : apparently implying ex- 

 actly what is maintained above. See 435. 



