Coenosarc sentence example

coenosarc
  • The coenosarc constitutes a system by which the digestive cavity of any one polyp is put into communication with that of any other individual either of the trophosome or gonosome.
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  • In this manner the food absorbed by one individual contributes to the welfare of the whole colony, and the coenosarc has the 6 C FIG.
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  • (From Moseley.) irregular coenosarcal canals, the coenosteum may contain, in its superficial portion, chambers or ampullae, in which the reproductive zoids (medusae or gonophores) are budded from the coenosarc.
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  • (After coralline may be regarded as a form of Moseley.) hydroid colony in which the coenosarc forms a felt-work ramifying in all planes, and in which the chitinous perisarc is replaced by a massive calcareous skeleton.
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  • A typical Siphonophore is a stock or cormus consisting of a number of appendages placed in organic connexion with one another by means of a coenosarc. The coenosarc does not differ in structure from that already described in colonial Hydrozoa.
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  • The coenosarc may consist of a single elongated tube or stolon, forming the stem or axis of the cormus on which, usually, the appendages are arranged in groups termed cormidia; or it may take the form of a compact mass of ramifying, anastomosing tubes, in which case the cormus as a whole has a compact form and cormidia are not distinguishable.
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  • In the Disconectae the coenosarc forms a spongy mass, the " centradenia," which is partly hepatic in function, forming the socalled liver, and partly excretory.
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  • In Velella the pneumatophore becomes of complex structure and sends air-tubes, lined by a chitin and resembling tracheae, down into the compact coenosarc, thus evidently serving a respiratory as well as a hydrostatic function.
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  • In forms with a compact coenosarc such as Velella, Physalia, &c., the separate cormidia cannot be sharply distinguished, and such a condition is described technically as one with " scattered " cormidia.
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  • Thus from the original planula three appendages are, as it were, budded off, while the planula itself mostly gives rise to coenosarc, just as in some hydroids the planula is converted chiefly into hydrorhiza.
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  • The planula develops, on the whole, in a similar manner, but the ectodermal invagination arises, not at the pole of the planula, but on the side of its broader portion, and gives rise, not to a pneumatophore, but to a nectocalyx, the primary swimming bell or protocodon (" Fallschirm ") which is later thrown off and replaced by secondary swimming bells, metacodons, budded from the coenosarc.
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  • Thus a bract may be regarded, with Haeckel, as a modified umbrella of a medusa, a siphon as its manubrium, and a tentacle as representing a medusan tentacle shifted in attachment from the margin to the sub-umbrella; or a siphon may be compared with a polyp, of which the single tentacle has become shifted so as to be attached to the coenosarc and so on.
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  • This sheet of tissue is called the coenosarc. Its lower surface is clothed with a layer of calicoblasts which continue to secrete carbonate of lime, giving rise to a secondary deposit which more or less fills up the spaces between the individual coralla, and is distinguished as coenenchyme.
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  • As the buds develop the canal system becomes much extended, and calcareous tissue is deposited between the network of canals, the confluent edgezones of mother zooid and bud forming a coenosarc. As the process continues a number of calicles are formed, imbedded in a spongy tissue in which the canals ramify, and it is impossible to say where the theca of one corallite ends and that of another begins.
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  • After division the corallites continue to grow upwards, and their zooids may remain united by a bridge of soft tissue or coenosarc. But in some cases, as they grow farther apart, this continuity is broken, each corallite has its own edge-zone, and internal continuity is also broken by the formation of dissepiments within each calicle, all organic connexion between the two zooids being eventually lost.
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  • - Branching or massive aporose corals, the calices projecting above the level of a compact coenenchyme formed from the coenosarc which covers the exterior of the corallum.
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  • 5), the blastostyles gradually lose their nutritive function and the organs connected with it; the mouth and tentacles disappear, and the blastostyle obtains the nutriment necessary for its activity by way of the coenosarc. In the Calyptoblastea, where the polyps are protected by special capsules of the perisarc, the gonothecae enclosing the blastostyles differ from the hydrothecae protecting the hydranths (fig.
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  • The gonads (g) are produced on the manubrium, which has a hollow endodermal axis, termed the spadix (sp.), in open communication with the coenosarc of the polyp-colony and serving for the nutrition of the generative cells.
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  • In the Stylasteridae sessile gonophores are formed, always by budding from the coenosarc. In Distichopora the gonophores have radial canals, but in other genera they are sporosacs with no trace of medusoid structure.
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  • Gonophores, produced either on the gonostyles already mentioned or budded, as in hydrocorallines, from the coenosarc, i.e.
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  • In forms in which, on the other hand, the coenosarc forms an elongated, tubular axis or stem, the appendages are arranged as regularly recurrent cormidia along it, and the cormidia are then said to be " ordinate."
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