134 PHYCOMYCETES. 



and branched conidiophores with light-brown conidia arise from 

 their underside. Numerous oospores may be found in the leaves. 

 Kirchner ^ observed the disease on leaves of four-year-old plants, 

 yet without injurious effects. 



The follovnng are other British or American species : 



Peronospora ficariae, Tul. On Ranunculus, Myosunis, etc. 



P. corydalis, De By. On Corydalis and Dicentra. 



P. violae, De By. On Viola tricolor. 



P. arenariae var. macrospora, Farl. On Silene. 



P. alsinearum, Gasp. On Cerastimn. 



P. claytoniae, Farl. On Claytonia. 



P. lini, Schroet. On Linum. 



P. potentillae, De By. On Eosaceae e.g. Qeum, Fragaria, and Potentilla, 



P. Arthuri, Farl. On Oenothera. 



Fig. 44. — Pei'onospora atsineai-um. Sexual organs, a. Young condition ; h, for- 

 mation of ovum and fertilization-tube ; c, after fertilization, (peripLism some- 

 what contracted by preparation, and the fertilization-tube unusually thick) ; 

 71, antheridium ; o, oogonium, x 350. (After De Bary.) 



P. leptosperma, De By. On Compositae e.g. Artemisia. 



P. Candida, Fuck. On Androsace and other Primulaceae. 



P. cynoglossi, Burrill. On Cynogloss^im. 



P. myosotidis, De By. On Myosotis and Echinospermum. 



P. sordida. Berk. On Nicotiana and Scrophularia. 



P. hyoscyami, D. By. On Tobacco in America and Australia (Gard. 

 C/iron. IX.). 



P. linariae, Fckl. On Linaria. 



P. gfrisea, Ung. On Veronica. 



P. lophauti, Farl. On Lopkanthus. 



P. alta, Fckl. On Plantago. 



P. (Plasraopara) cubensis is reported ^ as causing an extensive and 

 destructive disease of cucumbers (Cucumis and Cucurbita). 



P. (Plasmopara) australis, Speg. On Echinocystis lohata and Sicyos 

 angulatus in America. 



^Kirchner, Zeitschrift f. Pflamenkrankheiten, 1892. 

 -Humphrey, Report of the Mass. Agric. Kxper. Stat., 1890-92. 

 Massee, Gardener's Chronicle, Vol. xvii., p. 656, 1895. 



