Identifier: royalnaturalhist612lyde (find matches)
Title: The royal natural history
Year: 1893 (1890s)
Authors: Lydekker, Richard, 1849-1915 Sclater, Philip Lutley, 1829-1913 Frostick, W. B., former owner. DSI Brooks, W. T., former owner. DSI
Subjects: Zoology Natural history
Publisher: London and New York : Frederick Warne & Co.
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

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r part is simply surrounded by polyps,and the lower a cylindrical stalk. A stock of this last-named type may lie for twoor three consecutive weeks like a wrinkled turnip at the bottom of an aquarium,with all its activities suspended; no individual polyp appears; no food is taken in,and the circulation of water, necessary for the life of the stock, does not takeplace. After a time, however, the fine pores begin to take in water again, thesurface becomes smoother, and gradually, as the individual polyps appear andstretch out their tentacles, the colouring of the whole stock becomes more vividand more delicate. The stock lengthens and thickens, and the white crowns oftentacles stand out in dazzling contrast to the red of their bodies and of the 51* CCELENTERA TES. common trunk. The foot swells out like an onion and becomes transparent,curves, and sinks into the stand; and the stock, which during its period ofinactivity lay prone on the ground, assumes an erect position. In these sea-pens
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an alcyonarian coral, Alcyonium (nat. size). the parts of the stock may be compared with the parts of a feather, the whole being bilaterally symmetrical, and the single polyps being carried on the leaf-like ral appendages of the stem. The sexual animals, which are provided with all rgans necessary for a polyp, take in the food and reproduce themselves. The other less perfect brethren, called zooids, although more or less resembling these, CORALS. 5i3 have remained at a lower stage of development, are smaller, and have neithertentacles nor reproductive organs. These zooids appear to perform only onefunction, namely, to pump water through the body of the stock. In this importantwork the higher individuals no doubt assist, as indeed in most alcyonid-stocksthey alone must do the work, there being no such specialised pumpin^-polyps. In addition to the small, isolated calcareous particles already mentionedwithin the bodies of the individual polyps, sea-pens have a further support in theform

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