JHE FUNGI 93 
but in many cases they seem to arise in a purely vege- 
tative way without any formation of sexual organs. 
Many of the Ascomycetes show remarkable polymor- 
phism, this being especially marked in the “ Black- 
fungi” or Pyrenomycetes, of which the ergot of the 
rye and the “black knot” of cherries and plums are 
examples. In these there are, in addition to the asco- 
spores, several different forms of conidia cut off from 
the tips of the hyphe. 
THE BASIDIOMYCETES 
The Basidiomycetes include most of the more familiar 
large fungi, known popularly as mushrooms, toadstools, 
puff-balls, etc. These fungi have no very evident affin- 
ity with the sac-fungi, and as yet none of them have 
shown any traces of sexual reproduction. The great 
majority are saprophytes, the mycelium or vegetative 
filaments ramifying extensively through the substratum, 
which usually is earth rich in decaying vegetation, rot- 
ten wood, or similar dead organic matter. From this 
mycelium the spore-fruit arises, apparently in all cases 
as a purely vegetative growth. Most Basidiomycetes 
produce but one kind of spores, borne upon club-shaped 
cells known as basidia (Fig. 25, E), and it is still an 
open question whether the spore-fruit in these can prop- 
erly be compared to that of the Ascomycetes. 
The basidia are swollen, club-shaped cells, borne at 
the end of hyphe, and from each basidium grow out 
several, usually two or four, little protuberances, each 
of which produces a single spore at the tip. These 
basidia are usually formed upon special parts of the 
