Gonophores sentence example

gonophores
  • In some cases both free medusae and gonophores may be produced from the same hydroid colony.
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  • This is the case in Syncoryne mirabilis (Allman [1], p. 278) and in Campanularia volubilis; in the latter, free medusae are produced in summer, gonophores in winter (Duplessis [14]).
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  • The next step is illustrated by the female gonophores of Cladocoryne, where the radial and ring-canals F G H Modified from Weismann, Entstehung der Sexualzellen bei den Hydromedusen.
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  • The hydroid Dicoryne 'is re- ' markable for the possession of gonophores, which are ciliate and become detached and swim away by means of their cilia.
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  • It has been maintained that the gonads of Hydra represent sporosacs or gonophores greatly reduced, with the last traces of medusoid structure completely obliterated.
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  • Huxley, the sporosac is the starting-point of an evolution leading up through the various types of gonophores to the free medusa as the culminating point of a phyletic series.
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  • When sessile gonophores are produced, they may show all stages of degeneration.
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  • Other hydroids are Garveia, Bimeria, Eudendrium and Heterocordyle, with gonophores, and Dicoryne with peculiar sporosacs.
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  • Trophosome encrusting with hydranths of Bougainvillea-type, polyps differentiated into blastostyles, gastrozoids and dactylozoids; gonosome free medusae or gonophores.
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  • Corymorphidae (including the medusa-family Hybocodonidae).--, Trophosome solitary polyps, with two whorls of tentacles; gonosome, free medusae or gonophores.
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  • Coryne, a common British longed into a brood pouch conhydroid, produces gonophores; taining embryos.
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  • Trophosome polyps forming branching colonies of which the stem and main branches are thick and composed of a network of anastomosing coenosarcal tubes covered by a common ectoderm and supported by a thick chitinous perisarc; hydranths similar to those of Coryne; gonosome, sessile gonophores.
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  • The blastostyles, gonophores and gonothecae furnish a series of variations which can best be considered as so many stages of evolution.
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  • Gonostyles, appendages which produce by budding medusae or gonophores, like the blastostyles of a hydroid colony.
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  • The most usual condition, however, is that in which sessile medusoid gonophores or sporosacs are produced.
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  • The rhodalome of some Rhodalidae, consisting of siphon, tentacle and one or more gonophores.
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  • The athorome of Physophora, &c., consisting of siphon, tentacle, one or more palpons with palpacles, and one or more gonophores.
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  • M, Medusoid gonophores.
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  • If fertile they become free medusae or sessile gonophores.
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  • The gonophores of different hydroids differ greatly in structure from one another, and form a series showing degeneration of the medusa-individual, which is gradually stripped, as it were, of its characteristic features of medusan organization and finally reduced to the simplest structure.
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  • Allman, however, regarded this type of gonad as equivalent to a sporosac, and considered the medusa bearing them as a non-sexual organism, a " blastocheme " as he termed it, producing by budding medusoid gonophores.
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  • If it is assumed that all these genera bore gonophores ancestrally, then medusa of similar type must have been evolved quite inde pendently in a great number of cases.
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  • Hence it may be concluded that the gonophores are degenerate medusae, and not that the medusae are highly elaborated gonophores, as the organ-theory requires.
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  • Thus many subdivisions are diagnosed by setting free medusae in one case, or producing gonophores in another, although it is very obvious, as pointed out above, that a genus producing medusae may be far more closely allied to one producing gonophores than to another producing medusae, or vice versa, and that in some cases the production of medusae or gonophores varies with the season or the sex.
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  • Here belong the deep-sea genera Monocaulus and Branchiocerianthus, including the largest hydroid polyps known, both genera producing sessile gonophores.
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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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