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. 173 them the small cerebral hemispheres, then the large optic lobes (in which originate the nerves of sight), and, last of all, the cerebellum. Not till we reach Man and the Apes do we find the cerebrum so highly developed as to overlap both the olfactory lobes in front and the cerebellum behind. Functions of the Brain.—The cerebrum is the seat of in- telligence and will. It has no direct communication with the outside wrorld, receiving its consciousness of external objects and events through the spinal cord and the nerves of special sense.86 The cerebellum seems to preside over the co-ordination of the muscular movements. When removed, the animal
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Fto. 141.—A, C, tipper and side views of the Brain of a Lizard ,• B, D, upper and side views of the Brain of a Turkey: Olf, olfactory lobes; Hmp, cerebral hemispheres; Pn, pineal gland ; Mb, optic lobes of the middle brain ; Cb, cerebellum; MO, me- dulla oblongata; ii, optic nerves; iv and vi, nerves for the muscles of the eye; Py, pituitary body. desires to execute the mandates of the will, but cannot; its motions are irregular, and it acts as if intoxicated. It is usually largest in animals capable of the most compli- cated movements; being larger in the Ape than in the Lion, in the Lion than in the Ox, in Birds than in Eep- tiles. The cerebellum of the Frog is, however, smaller than that of Fishes (Figs. 139,140). The olfactory and op- tic lobes receive the messages from their respective nerves.

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