330 FUNGI 



Fossil Form. 



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



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. Xat., 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 Bar}^ — Research into the Nature of the Potato-fungus (Phytophthora infestans de 



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

 De Bar}'— Zur Kenntniss der Peror.osporeen (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^ 



1881, T. i.. No. 6, and 1882, T. ii.. No. 27 j. 

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

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

 Schroter — Protomyces graminicola {ibid., 1879, p. 83). 

 W. 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). [^ee 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 algas (Cladophora, Mougeotia, 

 Spirog}Ta, ]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- 

 hyphas bv transverse walls. Of these cells, some swell and become 

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



