File:Animal and vegetable physiology, considered with reference to natural theology (1836) (14578091548).jpg

Identifier: animalvegetable01roge (find matches)
Title: Animal and vegetable physiology, considered with reference to natural theology
Year: 1836 (1830s)
Authors: Roget, Peter Mark, 1779-1869
Subjects: Biology Physiology Plant physiology Natural theology
Publisher: Philadelphia, Carey, Lea & Blanchard
Contributing Library: NCSU Libraries
Digitizing Sponsor: NCSU Libraries

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ry part of the ocean.* In some parts of the Greenlandseas they swarm to such an extent that they give a visibletinge to the colour of the waves for hundreds of miles. Thetotal number of these animals dispersed over that space sur-passes the utmost stretch of the imagination. In these si-tuations a cubic foot of water, taken indiscriminately, wasfound by Mr. Scoresby to contain above 100,000 of thesediminutive medusae. Belonging to the tribe of Medusaria is a singular genus, • The luminous property of sea water, or its phosphorescence, as it is some-times called, generally arises from the presence of minute medusec, whichare met with in greatest numbers at the surfiice, being spccifially lighter thanthe surrounding fluid. 144 THE MECHANICAL FUNCTIONS. denominated the Beroe, (Fig. 82 and 83,) which is remark-able for its organs of progressive motion. Its body is eitherglobular, or oblong, and it swims with its aicis in a verticalposition. Eight longitudinal bands or ridges, which^have
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been sometimes compared to ribs, extend down its sides,like those of a melon; and along each of these is attached aset of little membranes, extended horizontally, and support-ed on radiating fibres; so that they bear a pretty exact re-semblance to the fin of a fish. Their action is not unlikethat of the wings of a bird; for they are made to flap up anddown, striking the water vertically, and communicating anascending impulse to the body. This animal is also pro-vided with two very long and slender processes, which comeout from the sides of the body, and from these a great num-ber of still finer filaments, or cilia, proceed: the whole ap-paratus is highly sensitive and irritable, and on the slightesttouch the filaments are thrown into spiral coils, and retractrapidly within the body. They thus act the part of tenta-cula, or delicate organs, both of touch and of prehension.* Itwas observed by Fabricius, that when a Beroe is cut intomany pieces, each piece continues to live, and to swim

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