210 FUNCTIONS OF THE NERVOUS SYSTEM. 



to that of Birds ; but its breadth and depth are far less. The largest Cerebra 

 among Fishes are found in the Shark tribe; the superior intelligence of 

 which is well known to those who have had the opportunity of observing 

 their habits ; and it is interesting to remark, that their surface occasionally 

 presents an appearance of rudimentary convolutions. 



285. Comparative Anatomy, then, fully bears out the general doctrine, 

 that the Cerebrum constitutes the organ of Intelligence, as distinguished from 

 those mere Instincts by which many of the lower animals seem to be almost 

 entirely guided. By Intelligence, we do not mean, however, the reasoning 

 faculties only, but the combination of those powers which are of an educable 

 character, and which become the springs of voluntary action in very different 

 proportions in different animals of the same tribe ; as distinguished from 

 those which have an immediate relation to the wants of the corporeal system, 

 and which are automatic and invariable in the several individuals of the same 

 species. Observation of the Human species exhibits the same distinction. 

 When the Brain is fully developed, it offers innumerable diversities of form 

 and size, among various individuals ; and there are as many diversities of cha- 

 racter. It may be doubted if two individuals were ever exactly alike in this 

 respect. That a Brain which is greatly under the average size, is incapable 

 of performing its proper functions, and that the possessor of it must neces- 

 sarily be more or less idiotic, there can be no reasonable doubt. On the other 

 hand, that a large well-developed Brain is found to exist in persons, who 

 have made themselves conspicuous in thfc world by their attainments or their 

 achievements, may be stated as a proposition of equal generality. In these 

 opposite cases, we witness most distinctly the antagonism between the in- 

 stinctive and voluntary powers. Those unfortunate beings, in whom the Brain 

 is but little developed, are guided almost solely by their instinctive tendencies, 

 which frequently manifest themselves with a degree of strength that would 

 not have been supposed to exist : and occasionally new instincts present 

 themselves, of which the Human being is ordinarily regarded as destitute.* 

 On the other hand, those who have obtained most influence over the under- 

 standings of others, have always been themselves persons of strong volitional 

 powers ; in whom the instinctive tendencies have been subordinate to the wih 1 , 

 and who have given their whole energy to the particular object of their pur- 

 suit. It is very different, however, with those who are actuated by what is 

 ordinarily termed genius; and whose influence is rather upon the feelings 

 than upon the understandings, of those around them. Such persons are often 

 very deficient in the power of even comprehending the ordinary affairs of 

 life ; and still more commonly, they show an extreme want of judgment in 

 the management of them, being under the immediate influence of\their pas- 

 sions and emotions, and not having brought these under the control of their 

 intelligent will. The life of a genius, whether his bent be towards poetry, 

 music, painting, or pursuits of a more material character, is seldom one which 

 can be held up for imitation. In such persons, the general, power of the 

 mind being low, the Brain is not usually found of any great size. The mere 

 comparative size of the Brain, however, affords no accurate measure of the 

 amount of mental power ; we not unfrequently meet with men possessing 

 large and well-formed heads, whilst their capacity is not greater than that of 

 others, the dimensions of whose crania have the same general proportion, but 

 are of much less absolute size. Large brains, with deficient activity, are 



* A remarkable instance of this has been recently published. A perfectly idiotic girl, 

 in Paris, having been seduced by some miscreant, was delivered of a child without 

 assistance. It was found that she had gnawed the umbilical cord in two ; in the same 

 manner as is practised by the lower animals. It is scarcely to be supposed that she had 

 any idea of the object of this separation. 



