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Show 268 PHYSIOGNOMY OF I>LANTS. In Ehrenberg's Classification (Abhandlungen der Akad der Wiss. zu Berlin aus dcm, .J. 1832, s. 393-432), Coral-animals (often improperly called, in English works, Coral-insects) are divided into two great classes: the single-mouthed Anthozoa, which are either free or capable of detaching themselves, being the animal-corals, Zoocorallia j and those in which the attachment is permanent and plantlike, being the Phyto-corals. To the first order, the Zoocorallia, belong the Hydras or Arm-polypi of Trembley, the Actinire decked with beautiful colors, and the mushroom-corals j to the second order or Phyto-corals belong the Madrepores, the Astrreids, and the Ocellinre. The Polypi of the second order are those which, by the cellular wave-defying ramparts which they construct, are the principal subject of the present note. These ramparts consist of an aggregate of coral-trunks, which, however, do not instantly lose their common vitality as does a forest-tree when cut down. Every coral-trunk is a whole which has arisen by a formation of buds taking place according to certain laws, the parts of which the whole consists forming a number of organically distinct individuals. In the group of Phyto-corals these individuals cannot detach themselves at pleasure, but remain united with each other by thin plates of carbonate of lime. It is not, therefore, by any means the case that each trunk of coral has a central point of common vitality or life. (See Ehrenberg's Memoir, above referred to, s. 419.) The propagation of coral-animals takes place, in the one order, by eggs or by spontaneous division j and in the other order, by the formation of buds. It is the latter mode of propagation which, in the development of individuals, is the most rich in variety of form. Coral-reefs (according to the definition of Dioscorides, sea-plants, a forest of stone-trees, Lithodendra) are of three kinds j- coast-reefs, called by the English "shore or fringing reefs,'' which are immediately connected with the coasts of continents or islands, as almost all the coral banks of the Red Sea seen during an eighteen months' examination by Ehrenberg and Hemprich j-" barrier-reefs," 11 encircling- reefs,'' as the great Australian barrier-reef on the north-east coast of New Holland, extending from Sandy Cape to the dreaded Torres Strait j and as the encircling-reefs surrounding the islands of Vanikoro (between the Santa Cruz group and the New Hebrides) |
