in the
autumn or spring, forming black lines rupturing the epidermis.

Probably to be associated with the lower _Basidiomycetes_ are the
large fungi of which _Tremella_ (Fig. 51, _A_) is an example. They are
jelly-like forms, horny and somewhat brittle when dry, but becoming
soft when moistened. They are common, growing on dead twigs, logs,
etc., and are usually brown or orange-yellow in color.

Of the higher _Basidiomycetes_, the toadstools, mushrooms, etc., are
the highest, and any common form will serve for study. One of the most
accessible and easily studied forms is _Coprinus_, of which there are
several species growing on the excrement of various herbivorous
animals. They not infrequently appear on horse manure that has been
kept covered with a glass for some time, as described for _Ascobolus_.
After two or three weeks some of these fungi are very likely to make
their appearance, and new ones continue to develop for a long time.

[Illustration: FIG. 48.--_A_, young. _B_, full-grown fruit of a
toadstool (_Coprinus_), x 2. _C_, under side of the cap, showing the
radiating "gills," or spore-bearing plates. _D_, section across one of
the young gills, x 150. _E_, _F_, portions of gills from a nearly ripe
fruit, x 300. _sp._ spores. _x_, sterile cell. In _F_, a basidium is
shown, with the young spores just forming. _G_, _H_, young fruits,
x 50.]

The first trace of the plant, visible to the naked eye, is a little
downy, white speck, just large enough to be seen. This rapidly
increases in size, becoming oblong in shape, and growing finally
somewhat darker in color; and by the time it reaches a height of a few
millimetres a short stalk becomes perceptible, and presently the whole
assumes the form of a closed umbrella. The top is covered with little
prominences, that diminish in number and size toward the bottom. After
the cap reaches its full size, the stalk begins to grow, slowly at
first, but finally with great rapidity, reaching a height of several
centimetres within a few hours. At the same time that the stalk is
elongating, the cap spreads out, radial clefts appearing on its upper
surface, which flatten out very much as the folds of an umbrella are
stretched as it opens, and the spaces between the clefts appear as
ridges, comparable to the ribs of the umbrella (Fig. 48, _B_). The
under side of the cap has a number of ridges running from the centre
to the margin, and of a black color, due to the innumerable spores