74 FUNGI . 
dom are spores and threads colourless or of bright tints. In 
the Mucedines, on the contrary, the threads are never coated, 
seldom dingy, mostly white or of pure colours, and the spores 
have less a tendency to extra development or multiplex septa- 
tion. In some genera, as in Peronospora for instance,* a 
secondary fruit is produced in the form of 
resting spores from the mycelium; and 
these generate zoospores as well as the 
primary spores, similar to those common 
in Alge. This latter genus is very de- 
structive to growing plants, one species 
being the chief agent in the potato disease, 
and another no less destructive to crops of 
onions. The vine disease is produced by a 
Fic. 40.-—Rhopalomyces Species of Oidiwm, which is also classed 
edulis with Mfucedines, but which is really the 
conidiiferous form of Erysiphe. In other genera, the majority 
of species are developed on decaying plants, so that, with the 
exception of the two genera mentioned, the Hyphomycetes exert 
a much less baneful influence on vegetation than the Conio- 
mycetes. The last section, including the Sepedoniei, has been 
already cited as remarkable for the suppression of the threads, 
which are scarcely to be distinguished from the mycelium; the 
spores are profuse, nestling on the floccose mycelium; whilst 
in the Trichodermacei, the spores are invested by the threads, as 
if enclosed in a sort of false peridium. A summary of the 
characters of the family may therefore be thus briefly ex- 
pressed :— 
Filamentous ; fertile threads naked, for the most part free or 
loosely compacted, simple or branched, bearing the spores. at their 
apices, rarely more closely packed, so as to form a distinct common 
stem = HYPHOMYCFTES. 
Having thus disposed of the Sporifera, we must advert 
to the two families of Sporidiifera. As more closely related 
to the Hyphomycetes, the first of these to be noticed is the 
* De Bary, A., ‘‘ Recherches sur les Champignons Parasites,” in ‘* Ann. des 
Sci. Nat.” 4™¢ sér, xx. p. 5; ‘‘ Grevillea,” vol. i. p. 150. 
