. A handbook of cryptogamic botany. Cryptogams. OOMYCETES 33» Schenk) ; or different individuals produce the oogones and the antherids (Lagenidium, Ancylistes). A perforation having been made in the oogonial wall, the whole of the protoplasm of the antherid empties itself into the oogone (there being no periplasm), and the united mass rounds itself off and becomes the oosperm. The germination of the oosperm has not been observed. Propagation takes place by means of zoospores (Lagenidium), and to this end either the whole thallus-hypha becomes transformed into a. zoosporange, or it is divided i
. A handbook of cryptogamic botany. Cryptogams. OOMYCETES 33» Schenk) ; or different individuals produce the oogones and the antherids (Lagenidium, Ancylistes). A perforation having been made in the oogonial wall, the whole of the protoplasm of the antherid empties itself into the oogone (there being no periplasm), and the united mass rounds itself off and becomes the oosperm. The germination of the oosperm has not been observed. Propagation takes place by means of zoospores (Lagenidium), and to this end either the whole thallus-hypha becomes transformed into a. zoosporange, or it is divided into a series of such. Each zoosporange sends out through the membrane of the host-cell to the surrounding water a protuberance, through which the contents escape after the fashion of Pythium, forming uniciliated zoospores, which ultimately attack the fresh cells of other algae. In Ancylistes the only propagation known is a process of extension of its hyphse from one host to another. Literature. Cornu—Monogr. des Saprolegn. {loc. cit.). Cornu—Note sur I'oospore du Myzocytium proliferum, Schenk (Bull. Soc. Bot> France, xvi., 1869, p. 222). Pfitzer—Ein neuer Algen Parasit (Monatsber. Berl. Acad., 1872). Schenk—Ueber das Vorkommen contractiler Zellen im Pflanzenreich (Wiirzburg, 1858). Zopf—Ueber einen neuen parasitischen Phycomyceten, &c. (Lagenidium) (Bot. Zeit.^ 1879. P- 35I). Order 3.—Monoblepharide^. The single genus Monoblepharis (Corn.), like the preceding group, is , closely re- lated to Peronosporese and especially to Py- thium. The thallus- hyphse bear both ter- minal and interstitial oogones, in which there is no preliminary dif- ferentiation of peri- plasm, but the whole protoplasm contracts and forms the 00- sphere, while the apex of the oogonial wall opens. The antherid (usually a cell adjoining an oogone) produces several swarming antherozoids, which escape, one of. Fig. 290.—Monoblepharis sphariccc Cornu. oogone, 0^ and antherid, a., antherozol
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