134 PHYCOMYCETES. 



and branched conidiophores with light-brown conidia arise from 

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

 Kirchner 1 observed the disease on leaves of four-year-old plants, 

 yet without injurious effects. 



The following are other British or American species : 



Peronospora ficariae, Tul. On Ranuncufas, Myosurus, etc. 



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



P. violae, De By. On Viola tricolor. 



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



P. alsinearum, Casp. On Cerastium. 



P. claytoniae, Farl. On Claytonia. 



P. lini, Scliroet. On Linum. 



P. potentillae, De By. On Eosaceae e.g. Geum, Fragaria, and PotentiUa, 



P. Arthuri, Farl. On Oenothera. 



Fio. 44. Peronospora alsinearum. Sexual organs, o, Young condition ; I, for- 

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

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

 n, antheridium ; o, oogonium. X 350. (After De Bary.) 



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



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



P. cynoglossi, Bun-ill. On Oynoglossum. 



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 '(&V//v/. 

 C/iron. ix.). 



P. linariae, Fckl. On Linaria. 



P. grisea, Ung. On Veronica. 



P. lophanti, Farl. On Lophanthus. 



P. alta, Fckl. On Plantago. 



P. (Plasmopara) cubensis is reported 2 as causing an extensive and 

 destructive disease of cucumbers (Cucumis and Cucurbita). 



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

 angulatus in America. 



1 Kirchner, Zeitschrift f. PJlanzenkrankheiten, 1892. 



-Humphrey, Report of the Man*. Arjr'ic. Exper. Stat., 1890-92. 

 Mussee, Gardener's Chronicle, Vol. xvn., p. 656, 1895. 



