FUNGI 
219 
Erysiphe commune on Polygonum aviculare; and Erysiphe cichoria- 
cearum on numerous Compositae and Verbenaceae. Podosphaera 
may be found on the leaves of young cherry trees and apple trees, 
and on young shoots of older trees. The infected leaves are likely 
to be more or less deformed. Phyllactinia is sometimes abundant on 
leaves of Alnus incana. It is also found on Celastrus, Desmodium, 
Typha, and on various members of the Amentiferae. For herbarium 
purposes they may be preserved by simply drying the leaves under 
Fig. 58.— Uncinula necator on Ampelopsis quinquefolia: A, four asci containing ascospores 
have been forced out by pressing on the cover; stained in fuchsin and mounted in balsam; B, a 
conidiospore; and C, an appendage of Microsphaera alni, drawn from living material. X192. 
light pressure. When needed for examination the leaf should be 
soaked in water for a few minutes, after which the perithecia may 
be scraped off and mounted in water. In mounting great care must 
be taken not to break off the appendages. The asci may be forced 
out by tapping smartly on the cover (Fig. 58). 
For permanent mounts of entire perithecia with appendages, fix 
in 5 per cent formalin 24 hours, wash in water 1 hour, stain in aqueous 
eosin 24 hours, remembering to keep all solutions slightly acid. 
Use the Venetian turpentine method. If chromic acid, corrosive 
