THE BRAIN. 509 
reached, the brain of the primates, and especially of man, has 
its surface enormously increased, owing to its numerous fis- 
sures and convolutions, which, in fact, arise from the growth 
of the organ being out of proportion to that of the bony case 
in which it is contained; and since those cells which go to 
Fic. 359.—Brain and spinal cord of frog (Bastian). A, olfactory lobes; B, cerebral lobes ; 
R, pineal body ; C, D, optic lobes; #, cerebellum; H, spinal cord. The cerebellum is 
notably small. 
make up the gray matter and are devoted to the highest func- ° 
tions, are disposed over the surface, the importance of the fact 
in accounting for the superior intelligence of the primates, 
and especially of man, becomes apparent. Depth of fissuring 
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 
Fie. 360. 
Fic. 360.—Brain of the pike, viewed from above (Huxley). A, the olfactory nerves or lobes, 
and beneath them the optic nerves ; B, the cerebral hemispheres ; C, the optic lobes; D, 
the cerebellum.” : . 
Fia. 861.—The brain of edible frog (Rana esculenta). 1x4. (After Huxley.) L.ol, the 
rhinencephalon, or olfactory lobes. with J, the olfactory nerves ; Hc, the cerebral hemi- 
spheres : F'h.o, the thalamencephalon with the pineal gland, Pn ; L. op, optic lobes ; C, 
cerebellum ; S.rh, the fourth ventricle; Afo, medulla oblongata. 
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 
