330 FUNGI 



FOSSIL FORM. 



Peronosporites (W.G.S.). This genus was founded by Mr. Worthing-- 

 ton Smith for the reception of a fossil fungus Peronosporites antiquarius- 

 (W.G.S.), first detected by Mr. Carruthers in the axis of a Lepidodendron 

 from the coal measures. Mycele and bodies which may well be oogones 

 are visible in the preparations. The fungus is probably nearly related 



to Pythium. 



LITERATURE. 



De Bary Recherches sur le developpement de quelqnes Champignons parasites 



(Ann. Sc. Nat., 4 ser., Tom. xx.). (Contains reference to older literature.) 

 De Bary Zur Kenntnissder Peronosporeen (Beitr. zur Morph. u. Physiol. d. Pilze, ii.). 

 De Bary Untersuch. liber die Peronosp. u. Saprolegn. (ibid., iv.). 

 De Bary Research into the Nature of the Potato-fungus (Phytophthora infestans de 



By.) (Journ. Roy. Agric. Soc., 1876, xii.). 

 De Bary Zur Kenntniss der Peronosporeen (Bot. Zeit., 1881). 

 Cornu Monogr. d. Saproleg. (Pythium) (Ann. Sc. Nat., 5 ser., Tom. xv.). 

 Hesse Pythium de Baryanum, Halle, 1874. 

 Millardet Le Mildiou (Paris, G. Masson, 1882 ; and Journ. d'Agric. pratique, 



1 88 1, T. i., No. 6, and 1882, T. ii., No. 27). 

 Pringsheim Die Saprolegnieen (Pythium) (Jahrb. wiss. Bot., i.). 

 Schroter Peronospora obducens (Hedwigia, 1877, p. 129). 

 Schroter Protomyces graminicola (ibid., 1879, p. 83). 

 \V. G. Smith Resting-spores (so called) of Potato Disease (Gard. Chron., 1875, iv., 



N.S. ; and 1876, vi., N.S.). 

 W. G. Smith Peronosporites antiquarius, W. G. S. (Gard. Chron., 1877). [See also 



G. Murray, Academy, 17 Nov. 1877 and following numbers ; and Williamson, 



Phil. Trans. Roy. Soc. Lond., 1881.] 

 A. Zalewski Zur Kenntniss der Gattung Cystopus (Bot. Centralb., 1883, No. 33). 



ORDER 2. ANCYLISTE^:. 



This order embraces a few genera which, so far as what is known of 

 them indicates, are related most nearly to Pythium. All the members 

 of the group are parasitic in fresh-water algae (Cladophora, Mougeotia, 

 Spirogyra, Mesocarpus, Closterium, &c.), and they are all farther charac- 

 terised by simplicity of structure. The thallus is represented by hyphae 

 at first undivided, which often extend from one end of the host-cell to 

 the other. Ancylistes Closterii (Pfitz.) displaces the chorophyll-plates of 

 its host, and ultimately causes the death of the cell. Lagenidium 

 (Schenk), found in filamentous algae, causes the separation of cell-contents 

 from cell-wall, and discolours the chlorophyll, which gathers together 

 into a mass. 



The sexual organs are formed by the division into cells of the thallus- 

 hyphae by transverse walls. Of these cells, some swell and become 

 oogones, while others remain small and act as antherids (Myzocytium,. 



