. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 32 POLYPIFERA. free, and change their position by means of their vibratile cilia. When the polypes are expanded, the sea-water has a free passage through the stomach to the gemmules, which receive new vigour from its influence, and they advance towards the open posterior part of the stomach, become entangled in its aper- ture, pass through the stomach, and escape through the mouth. They then move about, by means of their cilia, in search of a place where to fix and develope themselves. The stony branches of the Coral are
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 32 POLYPIFERA. free, and change their position by means of their vibratile cilia. When the polypes are expanded, the sea-water has a free passage through the stomach to the gemmules, which receive new vigour from its influence, and they advance towards the open posterior part of the stomach, become entangled in its aper- ture, pass through the stomach, and escape through the mouth. They then move about, by means of their cilia, in search of a place where to fix and develope themselves. The stony branches of the Coral are suffi- ciently short and strong to resist the violence of the sea, which otherwise would break so fragile a substance, but in the Gorgoniae and Antipathes the ramifications are so long and slender, that they would inevitably be broken by the movements of the surrounding water, were it not that the nature of their central axis is materially modified. Tins part of their structure is therefore very considerably modified in its texture, and being composed of flexible materials is enabled to bend beneath the passing current and rise again uninjured, while in the Isis Hippnris (Jig. 37) a similar result is ob- tained by combining the horny and calcareous Fig. Isis Hippurls. matter in alternate joints. In these latter polyparies, however, although their central axes are principally composed of corneous substance disposed in concentric layers, the living cortex itself is full of granules of a cal- careous nature mixed with colouring matter that varies in different genera, and as this cortex dries in a thick layer upon the central stem when the Gorgonia is removed out of the water, the varieties of colour exhibited bv these zoophytes is conspicuous even in our cabinets. Cavolini* prosecuted for two successive years, 1784-and 1785, his researches on the structure of Gorgonia vcrrucosa (Lam.), * Abhandlung ueber Pflauzen-tbiere, p. 48. and found the anatomy of the polypes dis- pers
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