THE CEREBRUM, AND ITS FUNCTIONS. 697 



mining the value to be assigned to the organological system of Gall and 

 Spurzheim and their followers. The Cerebrum of the Oviparous Vertebrata 

 is imt a miniature representative of that of Man, as a whole, but only of his 

 anti'i-ior lobes; as is sufficiently obvious from an examination of its connec- 

 tions with other parts, and from the absence of any other commissural con- 

 nections between its two hemispheres than those which are afforded by the 

 Sensory Ganglia. It is in the Implacental Mammals that we find the first 

 rudiments of the middle lobes of the Cerebrum, and of the proper inter- 

 cerebral commissure, the Corpus Callosum ; and even in the Rodents this is 

 but very imperfectly developed. As we ascend the Mammalian series, we 

 find the Cerebrum becoming more and more elongated posteriorly by the 

 development of the middle lobes, and the intercerebral commissure becomes 

 more complete; but we must ascend as high as the Carnivora, before we 

 find the least vestige of the posterior lobes; and the rudiment which these 

 possess is so rapidly enlarged in the Q t uadrumaua, that in some of that 

 group the posterior lobes are as fully developed in reference to the Cere- 

 brum as a whole, and as completely cover in the Cerebellum as in the Hu- 

 man subject. 1 The attention which has yet been given to this department 

 of inquiry has not hitherto done more than confirm the statement already 

 made with regard to the general correspondence between the development 

 of the Cerebrum and the manifestations of Intelligence; very decided evi- 

 dence of which is furnished by the great enlargement of the Cerebrum, and 

 the corresponding alteration in the form of the Cranium, which present 

 themselves in those races of Dogs most distinguished for their educability, 

 when compared with those whose condition approximates most closely to 

 what was probably their original state of wildness. 



566. This general inference drawn from Comparative Anatomy, is borne 

 out by observation of the Human species. When the Cerebrum is fully 

 developed, it offers innumerable diversities of form and size among various 

 individuals; and there are as many diversities of character. It may be 

 doubted if two individuals were ever exactly alike in this respect. That a 

 Cerebrum which is greatly under the average size is incapable of performing 

 its proper functions, and that the possessor of it must necessarily be more or 

 less idiotic, there can be no reasonable doubt. On the other hand, that a 

 large, well-developed Cerebrum is found to exist in persons who have made 

 themselves conspicuous in the world in virtue of their intellectual achieve- 

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

 cases, we witness most distinctly the antagonism between the Instinctive and 

 Voluntary powers. Those unfortunate beings in whom the Cerebrum 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 



1 It has been asserted by the followers of Gall, that the development of the Cere- 

 brum from behind forwards, as above described, is rather apparent than real: the 

 whole organ being in fact pushed backwards by the excessive development of the 

 anterior lobe. But the anatomical distinction between the anterior and middle lobes 

 is sufficiently obvious externally ; and that of the middle and posterior lobes is also 

 clearly marked out by the development of the posterior cornua of the lateral ventri- 

 cles, and the situation of the hippocampus major. Hence the facts above stated do 

 not admit of any such interpretation; and they are fully borne out by the history of 

 the Embryonic development of the Cerebrum in Man, which precisely follows the 

 above plan. It is not here denied that the anterior lobe of the Human Cerebrum is 

 remarkable for its great extension forwards; but still, the difference between the 

 Cerebrum of Man and that of the lower Mammalia consists much rather in the pro- 

 portional development of the posterior lobes, than in that of the anterior. 



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