THE BEAIN. 489 



lizard's brain; the lower, that of the bird (after Huxley and Carus). Letters as in 

 the preceding figure, except L. i, lamina ierfnincUis, or anterior wall of the third 

 venfricle; /. M, foramen of Monro; a, anterior commissure; T/i. E, thalamen- 

 cephalon; «, soft commissure; », posterior commissurej in), indicates the exact 

 point of exit of the fourth pair from that part of the brain which answers to the 

 value of VieuBsens. 



and especially of man, becomes apparent. Depth of Qssuring 

 is, however, of more importance than multiplicity of furrows ; 

 and it may be observed that intelligence is not always in pro- 

 portion to the extent to which the cerebral surface is broken 

 up into fissures and convolutions. The depth of the gray mat- 

 ter is also very variable, and seems to bear an important rela- 

 tion to psychic development. Man's brain, then, is character- 

 ized by its great size and complexity ; while those parts treated 

 elsewhere, concerned in co-ordination, vision, etc., are well 

 developed, the cerebrum, especially its convolutions as distin- 

 guished from its basal ganglia, is, out of all proportion, greater 

 than in any other animal. 



The gray matter of the brains of the higher vertebrates is 

 distributed as masses of ganglionic cells internally, and as a 

 fairly uniform layer over its surface. The brain of man weighs 

 about three pounds on the average, that of the male being 

 a few ounces (four to six) heavier than that of the female. 



Fig. 346. Pre. 347. Fio.'348. 



Fig. 346.— Brain of pigeonYafter Ferrier). 4, cerebral hemispheres; B, optic lobe; C, 



cerebellum, the lateral lobes of which are very small. 

 Fig. 347.— Brain and spinal cord of chick at sixteen days old; optic lobes, ft, are still 



in contact (after Owen and Anderson). 

 Fig. 348.— Brain and part of spinal cord of chick twenty days old, showing optic lobes 



widely separated and cerebellum, c, largely developed. 



The individual and race differences, though considerable, are 

 not comparable in degree to those that distinguish man from 

 even the highest apes, the brain of the latter weighing not 

 more than about one third as much as that of the human sub- 

 ject. While it has been shown that individual men and women, 

 having brains of average or even sub-medium weight, may reach 



