308 FUNCTIONS OF THE NERVOUS SYSTEM. 



stages of the inflammatory process consist. These changes, being accompanied 

 by turgescence of the vessels, and by effusion into the. tissue surrounding 

 them, must occasion a degree of pressure on the enclosed fibres, which de- 

 stroys their conducting power, and thus cuts off the body from connection 

 with the centre of the intellectual operations ; whilst they may at the same 

 time give rise to many irregular and involuntary movements of the muscles, 

 to which the fibres thus affected are distributed. 



282. This view is further supported by the researches of Foville, on the alte- 

 rations of the Brain which are connected with insanity. His observations are 

 deserving of great confidence, both for the sake of his own high character and 

 attainments, and on account of the careful manner in which they were made. 

 *To avoid trusting to his memory for comparison, Foville has been in the habit 

 of examining the brain of a person who died without any disease in this 

 organ, at the same time with that of one who died insane. In acute cases of 

 Insanity, he frequently found the cineritious portion intensely red, but without 

 adhesion to the membranes ; whilst in chronic cases, he found the cortical 

 substance indurated and adherent to the membranes. In nearly all cases of 

 Insanity accompanied with general Paralysis, he has found the white portion 

 of the brain injected and indurated ; and he conceives that the fibres had 

 become adherent to each other. It has been supposed by Calmeil, that the 

 paralysis of the insane is connected with disease of the cineritious substance ; 

 but Foville states that he and his colleagues have made many hundreds of 

 observations on cases, in which there were well-marked alterations of the 

 cortical substance of the brain, without any other manifestations during life 

 than disorder of the intellect. This view is supported by Bouillaud, and by 

 several other eminent pathologists ; as is also the other part of the proposition, 

 that morbid alterations in the medullary portion are connected with dis- 

 order in the transmission of motor impulses to the muscles. 



283. It is important to bear in mind the view to which we are thus con- 

 ducted, in regard to the relative offices of the gray and white matter, when 

 forming our opinions upon the functions of the Cerebrum in general, or of its 

 several parts, from the various data supplied to us by Comparative Anatomy, 

 and by experimental and pathological inquiry. For in regard to the first of 

 these sources it is to be remarked, that the size of the brain does not, con- 

 sidered alone, afford a means of judgment as to its power. The quantity of 

 gray matter on its surface should rather be our guide ; and this we may judge 

 of, not only by the depth of the layer, but by the complexity of the convolu- 

 tions by which the surface is extended. * In no class, save in Mammalia, do 

 we find the surface marked with convolutions; and in general we do not meet 

 with that fissure between the hemispheres which greatly increases the extent 

 of surface. In forming comparisons as to the connection between the size of 

 the Brain, and the intelligence, in different animals, we must not be at all 

 guided by its simple proportional dimensions ; since it is very evident, that it 

 is rather the proportion of the bulk of the brain to that of the whole body, 

 upon which we should found our comparison. But even this is not alto- 

 gether a safe guide; and many Physiologists have endeavoured to com- 

 pare the size of the brain with the aggregate bulk of the nerves proceeding 

 from it. This is a much fairer measure ; but it cannot be taken without great 

 difficulty. For all practical purposes, the comparison of the bulk of the Brain 

 with that of the Spinal Cord will probably answer very well. The following 

 table, the materials of which are drawn from M. Serre's Comparative Anatomy 

 of the Brain, exhibits the three diameters of the Brain of a number of different 

 animals, and the diameter of the Spinal Cord at the second cervical vertebrae. 

 The last three columns present in round numbers, the three diameters of the 

 Brain, reckoning that of the Spinal Cord as 1, for the sake of easy comparison. 



