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antheridium

antheridium

antheridium Sentence Examples

  • 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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  • an, Antheridium.

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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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  • hyphae derived from the 2, Separation of antheridium stalk-cell (st).

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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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  • are coenogametes), but that the antheridium disorganizes without passing its contents into the ascogonium.

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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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  • ascogonium and antheridium contain numerous nuclei; they are to be looked upon as gametangia in which there is no differentiation of gametes, and since they act as single gametes they are termed coenogametes.

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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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  • Oedogonium sp., oogonium antheridium at a node on at moment of fertilization a lateral appendage.

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  • antheridium before fertiliz E1.

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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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  • Polysiphonia sp., antheridium.

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  • ..Bangiaceae - Eti Florideae Eugleneae Chi Iromonadinae Pleurococcaceae - Endosphaeraceae Volvocaceae hlorosphaeraceae � CoNJuGA'rAE, Siphonales Tetrasporaceao Ulvaceae Confdyvaleb Characeae in the culminating stage of Fucus, where the oogonium is separated from the stalk-cell, so that unless it be contended that the Fucus is really a sporophyte which does not produce spores, and that the gametophyte is represented merely by the oogonium and antheridium, there is no semblance of alternation of generation in this case.

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  • A, Mature antheridium.

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  • B, Empty antheridium; p, prothallial cell; I, 2, cells of antheridial walls; 3, cap cell.

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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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  • Figure 1: Oogonia with inflated (left) or twisted (right) paragynous antheridium.

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  • an, Antheridium.

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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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  • 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.

    0
    0
  • 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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  • hyphae derived from the 2, Separation of antheridium stalk-cell (st).

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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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    0
  • 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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  • ascogonium and antheridium contain a number of nuclei (i.e.

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  • are coenogametes), but that the antheridium disorganizes without passing its contents into the ascogonium.

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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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  • ascogonium and antheridium contain numerous nuclei; they are to be looked upon as gametangia in which there is no differentiation of gametes, and since they act as single gametes they are termed coenogametes.

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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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    0
  • 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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  • Oedogonium sp., oogonium antheridium at a node on at moment of fertilization a lateral appendage.

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  • antheridium before fertiliz E1.

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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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  • Polysiphonia sp., antheridium.

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  • ..Bangiaceae - Eti Florideae Eugleneae Chi Iromonadinae Pleurococcaceae - Endosphaeraceae Volvocaceae hlorosphaeraceae � CoNJuGA'rAE, Siphonales Tetrasporaceao Ulvaceae Confdyvaleb Characeae in the culminating stage of Fucus, where the oogonium is separated from the stalk-cell, so that unless it be contended that the Fucus is really a sporophyte which does not produce spores, and that the gametophyte is represented merely by the oogonium and antheridium, there is no semblance of alternation of generation in this case.

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  • The antheridium (fig.

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  • A, Mature antheridium.

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  • B, Empty antheridium; p, prothallial cell; I, 2, cells of antheridial walls; 3, cap cell.

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  • It was in this case that Renault first made the exceedingly interesting discovery that each pollen-grain contains a group of cells, presumably representing an antheridium (fig.

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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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  • with the antheridium (p).

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  • with the antheridium (p).

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