Antheridium sentence example

antheridium
  • The sexual reproduction shows all transitions between forms which are normally sexual, like the Peronosporaceae, to forms in which no antheridium is developed and the oospheres develop parthenogenetically.
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  • The contents of the antheridium are not set free, but that organ penetrates the oogonium by means of a narrow outgrowth, the fertilizing tube, and a male nucleus then passes over into the single oosphere, which at first multinucleate becomes uninucleate before fertilization.
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  • In Cystopus Bliti the oosphere contains numerous nuclei, and all the male nuclei from the antheridium pass into it, the male and female nuclei then fusing in pairs.
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  • Young tube (a) of the antheridium multinucleate oogonium (og) which introduces the male and antheridium (an).
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  • In some forms we find definite male and female sexual organs (Sphaerotheca, Pyronema, &c.), in others the antheridium is abortive or absent, but the ascogonium (oogonium) is still present and the female nuclei fuse in pairs (Lachnea stercorea, Humaria granulata, Ascobolus furfuraceus); while in other forms ascogonium and antheridium are both absent and fusion occurs between vegetative nuclei (Humaria rutilans, and probably the majority of other forms).
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  • When the ascogonium (female organ) is present the ascogenous hyphae arise from it, with or without its previous fusion with an antheridium.
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  • The latter arise from the crown of a spirally coiled archicarp (bearing an ascogonium at its end) and a straight antheridium.
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  • Functional male and female organs have been shown to exist in Pyronema and Boudiera; in Lachnea stercorea both ascogonia and antheridia a are present, but the antheridium a1 is non-functional, the ascogonial _s- - (fema l e) nuclei fusing in pairs; /'y' this is also the case' in Humaria /;' h; granulate and Ascobolus furfurs -./ '"aceus, where the antheridium is _ / /, - entirely absent.
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  • The male organ (antheridium) consists of a few cells, the terminal one of which either abstricts from its end, or emits from its interior the non-motile spermatia, reminding us of those of the Florideae.
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  • In such a case the zoogamete is male, is called an antherozoid or spermatozoid, and arises in an antheridium; the larger gamete is an oosphere and arises in an oogonium.
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  • Fertilization is effected by the passive convection of a spermatium from the antheridium to the trichogyne, to which it adheres, and to which it passes over its nucleus through an open communication set up at the point of contact.
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  • In the light of our present knowledge of Ginkgo and the Cycads, there can scarcely be a doubt that spermatozoids were formed in the cells of the antheridium of the Cordaitean pollen-grain and that of other Palaeozoic Spermophyta; the an theridium is much more developed than in any recent Gymnosperm, and it may be doubted whether any pollen-tube was formed.
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