Title: Comparative zoology, structural and systematic : for use in schools and colleges
Identifier: comparativezool00orto (find matches)
Year: 1883 (1880s)
Authors: Orton, James, 1830-1877; Birge, E. A. (Edward Asahel), 1851-1950
Subjects: Zoology; Anatomy, Comparative; Physiology, Comparative
Publisher: New York : Harper & Bros.
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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THE NERVOUS SYSTEM. 171 the gray surface. The convolutions multiply and deepen as we ascend the scale of size and intelligence, being very complex in the Elephant and Whale, Monkey and Man. As a rule, they are proportioned to the intelligence of the animal; yet the brains of the Dog and Horse are smoother than those of the Sheep and Don- key. Evidently the quality of the gray mat- ter must be taken into account. Save in the bony Fishes, the cere- brum is the largest por- tion of the brain ; in Man it is over eight times heavier than the cerebellum. The cerebellum, or " little brain," lies be- hind the cerebrum, and, like it, presents an ex- ternal gray layer, with a white interior. In Mammals, it is likewise finely convoluted, con- sisting of gray and white laminae, and is divided into two lobes, or hemispheres. In the rest of the Vertebrates, the cere- bellum is nearly or quite smooth; and in the lowest Fish- es it is merely a thin plate of nervous matter. In many Vertebrates, however, it is larger, compared with the cere- brum, than in Man, since in Man the cerebrum is extraor- dinarily developed.
Text Appearing After Image:
Fig. 138. —Brain of the Horse—upper view, one half natural size: a, medulla oblongata; b, lat- eral and middle lobes of cerebellum; c, inter- lobular fissure; dy cerebral hemispheres; e, ol- factory lobes.

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