File:The physiology of the Invertebrata (1892) (14785130955).jpg

Identifier: cu31924003398538 (find matches)
Title: The physiology of the Invertebrata
Year: 1892 (1890s)
Authors: Griffiths, A. B. (Arthur Bower), 1859-
Subjects: Invertebrates
Publisher: New York, D. Appleton and Company
Contributing Library: Cornell University Library
Digitizing Sponsor: MSN

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OLOGY OF THE INVERTEBRATA. In some Crustacea, suckas the shore-crab (Carcinusmmnas), there is a large cere-bral ganglion which givesoff nerves to the eyes andantennae; while the ventralchain of ganglia (of otherforms) is fused into onemass (Pig. 64). Prom thismass radiate the nerve-cords.The nerve-cords connectingthe cerebral ganglion withthe nervous mass form theoesophageal ring or collar.There is in Carcinus a degreeof concentration of the gan-glionic cells, greater, in somerespects, than in the Verte-brates themselves. The nervous system ofAsta^us fiuviatilis (Fig. 65,and see also Fig. 13) con-sists of thirteen gangliajoined together by means ofcommissures. These gangliaare divided as follows: onecerebral, one sub-oesopha-geal, five thoracic, and sixabdominal ganglia. Thecerebral ganglion or braingives oflF nerves to the eyes;to the auditory organs; to the antennae; to the cara-pace in front of the cer-vical suture; to the greenglands; to the visceral nervous system; and to the sub-
Text Appearing After Image:
FlG. 65. Nervous System of Astacus.a = brain. !> = optic nerve, c = collar. d = sub-cesophageal ganglion,e = visceral nerve. / = posterio-lateral nerve. g = hepatic nerve. The stomach is turned on one side to show its nerves. PHYSIOLOGY OF THE INVERTEBRATA. 331 oesophageal ganglion. The latter nerves form the oesophagealcollar. The sub-oesophageal ganglion supplies the somites, fromthe fourth to the ninth, and their appendages, and gives offalso delicate nerves to the oesophagus. The five anterior ab-dominal ganglia supply the muscles and the appendages withnerves; while the sixth and last abdominal gangUon sendsnervous branches 1;o the telson (tail). The sixth abdominalganglion also sends out 4wo nerves, which unite into onecommon trunk, and from which nerve-fibres are given off to the intestine. The genital organs are supplied with nervesfrom the third, fourth, and fifth thoracic ganglia. The size of the ganglia is in direct ratio with thedevelopment of the segments and their appe

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