FUNCTIONS OF THE CEREBRUM. 365 



operations, indeed, seem to be of very much the same character as those 

 which we perform in our dreams, different trains of thought commencing as 

 they are suggested, and proceeding according to the usual laws, until some other 

 disturb them. Although it is customary to regard the Dog and the Elephant as 

 the most intelligent among the lower animals, it is not certain that we do so 

 with justice; for it is very possible that we are misled by that peculiar attach- 

 ment to Man, which in them must be termed an instinct, and which enters as 

 a motive into a large proportion of their actions ; and that, if we were more 

 acquainted with the psychical characters of the higher Quadrumana, we should 

 find in them a greater degree of mental capability than we now attribute to 

 them. One thing is certain, that, the higher the degree of intelligence 

 which we find characteristic of a particular race, the greater is the degree of 

 variation which we meet with in the characters of individuals ; thus every one 

 knows that there are stupid Dogs and clever Dogs, ill-tempered Dogs and 

 good-tempered Dogs, as there are stupid Men and clever Men, ill-tempered 

 Men or good-tempered Men. But no one could distinguish between a stupid 

 Bee and a clever Bee, or between a good-tempered Wasp and an ill-tempered 

 Wasp, simply because all their actions are prompted by an unvarying instinct. 

 481. It is important to bear in mind the view to which we have been con- 

 ducted, in regard to the relative offices of the vesicular and fibrous 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, by the comparison of the Cerebra of different individuals of the 

 Human race with each other and with their respective psychical manifestations, 

 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 

 vesicular 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 

 convolutions by which the surface is extended. In no class, save in Mam- 

 malia, 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 con- 

 nection between the size of the Cerebrum, 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 compari- 

 son. But even this is not altogether a safe guide; and many Physiologists 

 have endeavoured to compare 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 Cerebrum with that of the Spinal Cord will 

 probably answer very well. The following table, the materials of which 

 are drawn from M. Serres' Comparative Anatomy of the Brain, exhibits 

 the three diameters of the Cerebrum of a number of different animals, 

 and the diameter of the Spinal Cord at the second cervical vertebra. The 

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

 Cerebrum, reckoning that of the Spinal Cord as 1, for the sake of easy com- 

 parison. 



31* 



