500 | LIFE-HISTORIES | 
Fic. 328.—Powdery-mildew (Erysibe communis, Powdery-mildew Family, 
Erysibacee). The surface of a leaf upon which the fungus is parasitic, 
its horizontal hyphe spreading over the surface and attaching itself 
by sucking organs; and giving rise also to vertical hyphe producing 
dust-spores (c), and to fruiting bodies such as a, which contain sac- 
spore-cases such ase. The fruiting bodies b and d and the hyphe from 
which they arise belong to another fungus (Cincinnobolus) which is 
parasitic upon the mildew. Magnified about 450 diameters. (Tu- 
lasne.)—Powdery-mildews are all too common parasites upon the 
foliage of flowering plants both cultivated and wild. 
Fic. 329.—Powdery-mildew. Horizontal hyphe (a) from which arise 
““male’’ (b) and ‘‘female’’ (c) gametangia; the latter producing sac- 
spore-cases enclosed within a protective fruit-body (d, e). (Warming.) 
