Sentence Examples


  • Thus the typical hydroid colony starts from a " founder " polyp, which in the vast majority of cases is fixed, but which may be floating, as in Nemopsis, Pelagohydra, &c. The founder-polyp usually produces by budding polyp-individuals, and these in their turn produce other buds.
  • In this way the hydroid colony becomes composed of two portions of different function, the nutritive " trophosome," composed of non-sexual polyps, and the reproductive " gonosome," composed of sexual medusaindividuals, which never exercise a nutritive function while attached to the colony.
  • The hydroid colony shows many variations in form and architec- ture which depend simply upon differences in the methods in which polyps are budded.
  • Besides the three types of individual above mentioned, there are other appendages of hydroid colonies, of which the individuality is doubtful.
  • Such are the " guard-polyps " (machopolyps) of Plumularidae, which are often regarded as individuals of the nature of dactylozoids, but from a study of the mode of budding in this hydroid family Driesch concluded that the guard-polyps were not true polyp-individuals, although each is enclosed in a small protecting cup of the perisarc, known as a nematophore.

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