The Archegoniatae are characterized by a well-marked alternation of gametophyte and sporophyte generations; the former bears the sexual organs which are of characteristic structure and known as antheridia (male) and archegonia (female) respectively; the fertilized egg-cell on germination gives rise to the spore-bearing generation, and the spores on germination give rise directly or indirectly to a second gametophyte.
He was one of the first to point out the existence of certain cellular bodies in these plants which appeared to perform the functions of reproductive organs, and to them the names of antheridia and pistillidia were given.
In these cases we should expect to find some reduced process of fertilization similar to that of Humaria granulata among the ordinary Ascomycetes, where in the absence of the antheridia the female nuclei fuse in pairs.
In Peronospora, Saprolegnia, &c., the ends of the branches swell up into sporangia, which develop zoospores in their interior (zoosporangia), or their contents become oospheres, which may be fertilized by the contents of other branches (antheridia) and so form egg-cases (oogonia).
Sexual reproduction by oogonia and antheridia; asexual reproduction by zoospores or conidia.
Mycelium present, antheridia with antherozoids, oogonium with single oosphere: Monoblepharidaceae.
Mycelium present; antheridia but no antherozoids; oogonia with one or more oospheres: Peronosporaceae, Saprolegniaceae.
Mycelium poorly developed or absent; oogonia and antheridia (without antherozoids) known in some cases; zoospores common: Chytridiaceae.
Fungi with segmental thallus; sexual reproduction sometimes with typical antheridia and oogonia (ascogonia) but usually much reduced.
Monoblepharis has oogonia with single oospheres and antheridia developing a few amoeboid uniciliate antherozoids; these creep to the opening of the oogonium and then swim in.
In the rotting tissues branches of the older mycelium similarly swell up and form antheridia and oogonia (fig.
The Peronosporaceae reproduce themselves sexually by means of antheridia and oogonia as described in Pythium.
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.
Volvox sp., with a, antheridia, and o, oogonia.
The antheridia and oogonia are formed at the nodes of the appendages.
The antheridia are spherical orange-coloured bodies of very complex structure.
The sexual organs - oogonia and antheridia - are borne on special portions of the thallus in cavities known as conceptacles.
The antheridia, which arise in the conceptacular cavity as special cells of branched filaments, are similarly discharged whole, the antherozoids only escaping when the antheridia are clear of the conceptacle.
The antheridia have a similar origin and grouping on the male plant.
The discovery by Brebner of the specific identity of Haplospora globosa and Scaphospora speciosa marks an important step in the advance of our knowledge of the group. Three kinds of reproductive organs are known: first, sporangia, which each give rise to a single tetra-, or multi-nucleate non-motile, probably asexual spore; second, plurilocular sporangia, which are probably antheridia, generating antherozoids; and third, sporangia, which are probably oogonia, giving rise to single uninucleate non-motile oospheres.
Great numbers of antheridia are usually crowded together, when the part is distinguishable by the absence of the usual red colour.