134 



niYrOMVCKTES, 



and l.tranehed coiiidinphores with light-lirown 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 following are other British or American species : 



Peronospora ficariae, Tiil. On Ranvnculus, Mi/osnrns, etc. 



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



P. violae, De By. On Viola tricolor. 



P. arenariae var. niaci'ospora, Farl. On Silene. 



P. alsinearum, Casp. On Cerastiuni. 



P. claytoniae, Farl. On Claytonia. 



P. lini, Sihroet. On Limim. 



P. potentillae, De By. On Rosaceae e.g. Geum, Fragaria, and Potentilld, 



P. Arthuri, Farl. On Oenothera. 



Fia. 44. — Pcrono.ijiora alsinearum. Sexual organs, o, Yomig condition ; 6, for- 

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

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

 11, anthoridium ; o, oogonium, x 3f)0. (After De Bary.) 



P. leptosperma, De By. On Compositae e.g. Arte^nisia. 



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



P. cynoglossi, JJurrill. On Cynoglossurn . 



P. myosotidis, De By. On Myosotis and Echinos^^ermum. 



P. sordida, Jierk. On Nicotiana and Scrophularia. 



P. hyoscyami, D. By. On Tobacco in America and Australia {Uard. 

 Chron. ix.). 



P. linariae, Fckl. On Linaria. 



P. grisea, X'wj.. On Vei-onica. 



P. lophanti, Karl. On Lophcmthv.s. 



P. alta, Fckl. On I'Inntago. 



P. (Plasmopara) cubensis is reported- as causing an extensive and 

 destructive disease of cucumbers {Cucumis and Cucurbitd). 



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

 angtdatnH in America. 



' Kirchner, ZeiUchrift f. Pflanzaikrunkheiten, 1S92. 

 -Humphrey, Report of (he. Mans. Af/ric. Exper. Stal., 1S90-92. 

 Massee, Gardener's Chronicle, Vol. xvii., p. 656, 1S95. 



