File:The common frog (1874) (14595842199).jpg

Identifier: commonfrog00miva (find matches)
Title: The common frog
Year: 1874 (1870s)
Authors: Mivart, St. George Jackson, 1827-1900
Subjects: Rana temporaria Rana temporaria -- anatomy & histology
Publisher: London, Macmillan and co.
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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)■ 3. This third segment retains a great relative mag-nitude compared with that of man. (Fig. 74, d) 4. The fourth segment, however, consisting of theoptic lobes, attains a still further relative development,though consisting only of two bodies instead of four,but these contain a cavity not found in the corporaquadrigemina of the human brain. (Fig. 74, g.) 5. The fifth segment, the cerebellum, is very small,and smaller than the same part in animals both higherand lower in the scale ; indeed, in the frog class, thisorgan may be said to be at its minimum. When cutit exhibits no trace of an arbor vitcE. (Fig. 74, h) VIII.) THE COMMON FROG. 121 This fact has a special interest as bearing on allegedfunctions of this portion of the brain. It has been asserted by some that the cerebellumministers to the sexual functions ; by others that thispart co-ordinates and directs locomotive movements ;and quite lately, that it is related to movements ofthe eyes. 3
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Fig. 74.—Brain of Bull Frog in various views. 1, Dorsal view. 2, Lateral view.3, Transverse horizontal section showing the cavities of the olfactory cerebraland optic lobes. 4, Longitudinal section a little to the left of the median line.5, Longitudinal section in median line. The corpus striatum, c, is here exposedto view and also a body, g, within the optic lobes. 5, Longitudinal section inmedian line. In all five figures :—i, Olfactory nerve; 2, optic nerve: 4, auditorynerve ; a, olfactory lobe ; b, cerebral lobe ; c, corpus striatum; d, optic thalamus ;e, pineal gland; /, pituitary body ; g, optic lobes; /-;, cerebellum; i, medullaoblongata. The first tv^^o of these hypotheses seem to be com-pletely overthrown by our frog. In the first matterthere is anything but a deficiency of energy andactivity ; and as to the second, many reptiles are lessactive and continuous than the frog in their loco-motive efforts. As to the third hypothesis, it shouldbe remembered that the eyes of th

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