dz, by the hydranths, each with dactylozoid; gz, gastrozoid; b, mouth and tentacles; and, blastostyle; gon, gonophores; secondly, the " coenosarc," or rh, hydrorhiza.
15),the polyps produce buds right and left alternately, so that the hydranths are arranged in a zigzag fashion, forming a " scorpioid cyme," as in Obelia and Sertularia.
Driesch, in which, however, the primitively uniserial arrangement becomes masked later by secondary torsions of the hydranths.
In Tubularia by a process of decapitation the hydranths may separate off and give rise to a separate individual, while the remainder of the body grows a new hydranth.
Club-shaped hydranths with numerous tentacles, generally scattered irregularly, sometimes with a spiral arrangement, or in whorls (" verticillate ").
Trophosome arborescent, with hydranths of Bougainvillea-type; gonosome free medusae or gonophores, the medusae with solid tentacles in tufts (lophonematous).
Trophosome encrusting with hydranths of Bougainvillea-type, polyps differentiated into blastostyles, gastrozoids and dactylozoids; gonosome free medusae or gonophores.
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.
- Portion of the calcareous corallum of Millepora nodosa, showing the cyclical arrangement of the pores occupied by the " persons " or hydranths.
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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