PHYCOMYCETES 357 



{Bot.), vol. X. p. ^Gt^ (1869). — Forming very delicate white 

 patches on the under surface of the leaf; conidiophores 

 repeatedly dichotomously branched, branches spreading, 

 ultimate branchlets acute, straight, spreading; conidia 

 hyaline, elliptical, 25-32 X 18-20 /x. 



Peronospora hyoscyami, De Bary, Afi?i. Sci. Nat., ser. iv. 

 vol. XX. p. 123. — Forming dirty greyish-violet tufts of the 

 under surface of the leaf, sometimes small, at others 

 effused over the greater portion of the surface ; conidio- 

 phores 300-500 II high, averaging 300 /j., 5-8 times 

 dichotomously branched near the apex, branches spread- 

 ing, ultimate ones very divergent, short, awl-shaped ; 

 conidia small, elliptical, ends obtuse, pale dingy violet, 

 15-24 X 13-18 /x : oospore unknown. 



Peronospora maydis, Raciborski, Ber. Dentschen Bot. 

 GeselL, xv. p. 475, 4 figs. (1897). — Conidia emerging 

 through the stomata, 0*3 mm. high, and up to 25 /x thick, 

 with 1-3 main dichotomous branches, which are divided 

 at the tip into 2)~^ conical, pointed branchlets, each bearing 

 a smooth, hyaline, globose conidium 15-18 /x diam. ; 

 oospores globose, membrane smooth, 14-24 /x diam. 



ASCOMYCETES 



Spores produced in large mother-cells or asci ; asci 

 either naked, or more frequently produced within an 

 excipulum, or a perithecium ; perithecium either with a 

 distinct opening through which the asci escape at maturity, 

 or rupturing in an irregular manner, but never exposing 

 the disc or hymenium ; excipulum expanding and exposing 

 the hymenium at maturity. 



Gymnoasaceae. — Perithecium and excipulum absent, 



