e to the conidia in the same
way as we have seen in the mildews (Fig. 42, _A_).

Spore fruits much like those of the mildews are formed later, and
are visible to the naked eye as little yellow grains (Fig. 42, _D_).
These contain numerous very small spore sacs (_E_), each with eight
spores.

There are numerous common species of _Eurotium_, differing in color
and size, some being yellow or black, and larger than the ordinary
green form.

Another form, common everywhere on mouldy food of all kinds, as well
as in other situations, is the blue mould (_Penicillium_). This, in
general appearance, resembles almost exactly the herbarium mould, but
is immediately distinguishable by a microscopic examination (Fig. 42,
_G_).

In studying all of these forms, they may be mounted, as directed for
the black moulds, in dilute glycerine; but must be handled with
great care, as the spores become shaken off with the slightest jar.

Of the larger _Ascomycetes_, the cup fungi (_Discomycetes_) may be
taken as types. The spore fruit in these forms is often of
considerable size, and, as their name indicates, is open, having the
form of a flat disc or cup. A brief description of a common one will
suffice to give an idea of their structure and development.

_Ascobolus_ (Fig. 43) is a small, disc-shaped fungus, growing on horse
dung. By keeping some of this covered with a bell jar for a week or
two, so as to retain the moisture, at the end of this time a large
crop of the fungus will probably have made its appearance. The part
visible is the spore fruit (Fig. 43, _A_), of a light brownish color,
and about as big as a pin-head.

Its development may be readily followed by teasing out in water the
youngest specimens that can be found, taking care to take up a
little of the substratum with it, as the earliest stages are too
small to be visible to the naked eye. The spore fruits arise from
filaments not unlike those of the mildews, and are preceded by the
formation of an archicarp composed of several cells, and readily
seen through the walls of the young fruit (Fig. 43, _B_). In the
study of the early stages, a potash solution will be found useful in
rendering them transparent.

The young fruit has much the same structure as that of the mildews,
but the spore sacs are much more numerous, and there are special
sterile filaments developed between them. If the young spore fruit
is treated with chlor-io