ous
fungi," popularly understood, fungi may be the passive agents, yet
they cannot be ignored in an inquiry of this nature. Writing of the
Uses of Fungi, we have already shown that a large number are available
for food, and some of these real delicacies; so, on the other hand, it
becomes imperative, even with stronger emphasis, to declare that many
are poisonous, and some of them virulently so. It is not sufficient to
say that they are perfectly harmless until voluntarily introduced into
the human system, whilst it is well known that accidents are always
possible, and probably would be if every baneful fungus had the word
POISON inscribed in capitals on its pileus.

The inquiry is constantly being made as to what plain rules can be
given for distinguishing poisonous from edible fungi, and we can
answer only that there are none other than those which apply to
flowering plants. How can aconite, henbane, oenanthe, stramonium,
and such plants, be distinguished from parsley, sorrel, watercress,
or spinach? Manifestly not by any general characters, but by
specific differences. And so it is with the fungi. We must learn to
discriminate _Agaricus muscarius_ from _Agaricus rubescens_, in the
same manner as we would discriminate parsley from _AEthusa cynapium_.
Indeed, fungi have an advantage in this respect, since one or two
general cautions can be given, when none such are applicable for
higher plants. For instance, it may be said truly that all fungi
that exhibit a rapid change to blue when bruised or broken should
be avoided; that all Agarics are open to suspicion which possess an
acrid taste; that fungi found growing on wood should not be eaten
unless the species is well known; that no species of edible fungus
has a strong, unpleasant odour, and similar cautions, which, after
all, are insufficient. The only safe guide lies in mastering, one by
one, the specific distinctions, and increasing the number of one's
own esculents gradually, by dint of knowledge and experience, even as
a child learns to distinguish a filbert from an acorn, or with
wider experience will thrust in his mouth a leaf of _Oxalis_ and
reject that of the white clover.

One of the most deleterious of fungi that we possess is at the same
time one of the most beautiful. This is the _Agaricus muscarius_, or
Fly Agaric, which is sometimes used as a fly poison.[A] It has a
bright crimson pileus studded with pale whitish (sometimes yellowish)
warts, and a stem