File:Animal and vegetable physiology, considered with reference to natural theology (1836) (14741721986).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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and almost microscopic cells, spread over a flat membra-neous substance, resembling, in the flexibility of its texture,and its mode of subdivision, the leaves of plants. Thesecells are arranged in rows, with great regularity, like thoseof a honey-comb, as is seen in the magnified view of them,Fig. 64. In other tribes the inorganic base of support is internal,constituting a kind of skeleton or axis; the polypous mouthsbeing spread at intervals over the surface of the fleshy lay-er which covers this skeleton. This is the case with theGorgonia, jSntipathes, and the Coral, which exhibit stillcloser resemblances to the branched forms of vegetable stems.The flesh contains granules of calcareous matter, which, in thedried specimens, adhere to the surface of the stems. Fig.G5 is a branch of the Corallium rubum, of w^hich Fig. ^G
Text Appearing After Image:
is a magnified portion, showing the appearance of the poly-pes in their expanded and contracted states. The way inwhich the polypes are embedded in the flesh is seen in Fig.67, which represents a section of the Gorgonia Briareus,In many cases the polypes arc lodged in cup-like depres- 126 THE MECHANICAL FUNCTIONS. * sions in the surface of the calcareous axis, which affords themsome degree of protection. In Madrepores these depres-sions are crossed by radiating plates, adapted to the formand number of the tentacula. In Millej)ores the cells arecloser and more minute, and exhibit none of these star-likeradiations. In some species the plates have more of a pa-rallel arrangement; and in others they form a net-work. The material of which this axis, to which the polypes areattached, is composed, is of various kinds. Sometimes it ishorny, flexible, and elastic, corresponding in its nature toanimal membrane: at other times it is hard and calcareous,being composed principally of carbonate of

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