. Funghi, Ascomiceti, ustilaginales, uredinales. Funghi. IV] DISCOMYCETES 99 differisce nella sua trichogyne multicellulari e oiHumariagranulata, e forse alcune altre forme in cui il trichogyne, come il antheridium, ha dis- apparso. Un altro gruppo si distingue dalla oogonial pluricellulari regione del archicarp, che ha anche una levetta e una regione terminale (o) trichogyne di numerose celle ciascuna (fig. 58). Questo tipo di organo femmina viene a volte definita una scolecite. Essa si verifica in Lachnea cretea e in diverse specie di Asco- bolo e Ascophanus. In Ascobolus furficraceus diversi della CE

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. Fungi, ascomycetes, ustilaginales, uredinales. Fungi. IV] DISCOMYCETES 99 differs in its multicellular trichogyne, and oiHumariagranulata, and perhaps some other forms in which the trichogyne, like the antheridium, has dis- appeared. Another group is distinguished by the multicellular oogonial region of the archicarp, which has also a stalk and a terminal region (or trichogyne) of several cells each (fig. 58). This type of female organ is sometimes termed a scolecite. It occurs in Lachnea cretea and in several species of Asco- bolus and Ascophanus. In Ascobolus furficraceus several of the central cells communicate one with another by means of pores, but only one of them gives rise to asco- ^. „ , , , r x ' -^ ° Fig. 58. Ascobolus furfuraceus genous hyphae ; in some other species of Asco- Pers.; archicarp, X740; after bolus and in the genus Ascophanus ascogenous ° ^^' hyphae arise from several communicating cells; the same is true of Lachnea cretea, where three or four cells become practically continuous owing to the disappearance of the transverse septa between them. In the trichogyne also, or terminal region of the archicarp, pores are formed in the transverse walls, so that this multicellular organ offers no bar to the passage of male nuclei. Such structures may well have been derived from the Ascodesmis type by the elongation and transverse septation of the parts of the archicarp. Our knowledge of the sexual organs of the Pezizales thus suggests that they may have been derived, along two principal lines of development, from a common ancestor within the group. In only two other families of Discomycetes, the Rhizinaceae {Rhizina and Sphaerosomd) and the Geoglossaceae (Leotia) has an oogonium been recognized. In each of these a large fertile cell is present, but its develop- ment is not known and no suggestions as to phylogeny can therefore be based upon it. Our knowledge of the development and especially of the reproductive organs of the Discomycetes is still

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• bookcentury1900
• bookdecade1920
• booksubjectfungi
• bookyear1922