548 RELATION OF INTELLIGENCE TO CEREBRUM. 



would behave as lie did, that they never thought of tying 

 him." It were much to be wished, that all human beings 

 would imitate this docile Elephant's self-control. It is some- 

 times manifested, however, even in Infancy ; the painful 

 operation of lancing the gums being often sustained without 

 a cry, from the consciousness of the benefit derived from it. 



718. It has been stated that the relative amount of Intelli- 

 gence in different animals bears a pretty constant proportion 

 to the size and development of the Cerebral hemispheres 

 ( 452). That size alone, however, does not produce the dif- 

 ference, is evident from a number of facts. As we advance 

 from the lower to the higher Vertebrata, we observe an obvious 

 advance in the complexity of the structure of the brain. In 

 proportion to the increase in the number and depth of the 

 convolutions by which its surface is extended ( 456), do we 

 find an increase in the thickness of the layer of grey or 

 vesicular matter ( 61), which seems to be the real centre of 

 all the operations of the organ. The arrangement of the 

 white or tubular tissue ( 60), which forms the interior of 

 the mass, also increases in complexity ; and as we ascend 

 from the lower Mammalia up to Man, we trace a great in- 

 crease in the number of the fibres which establish communi- 

 cations between different parts of the surface. Still there can 

 be no doubt that the size of the Cerebrum, compared with that 

 of the Spinal Cord and of the Sensory Ganglia at its summit, 

 usually affords a tolerably correct measure of the intelligence 

 of the animal ; and that, even in comparing together different 

 Men, we shall find the same rule to hold good, when due 

 allowance has been made for the comparative activity of their 

 general functions, such as is expressed by the word tempera- 

 ment. Thus, two men, having brains of the same size and 

 general conformation, may differ greatly in mental vigour, 

 because the general system of one performs its functions 

 much more actively and energetically than that of the other. 

 For the same reason, a man of small brain, but whose general 

 habit is active, may have a more powerful mind than another 

 whose brain is much larger, yet whose system is inert, his 

 perceptions dull, and his movements languid. But of two 

 men alike in these respects, and having the same general con- 

 figuration of head, it cannot be doubted that the one with the 

 larger brain will surpass the other. It is a striking fact, that 



