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CHAPTER VHI.
TA EIATIONS OE FU N aT .
R e a l hybrids do not probably exist amongst Fungi, and if this
be true, one source of perplexity will he removed which renders
the task of discrimination of species difficult to the phseno-
gamic botanist. In organisms which depend so much upon
outward circumstances, considerable differences will indeed
occur, hut most of these, after a little study and experience,
are easily estimated.
The same species will for instance present variations m size
and colour, in the condition of the outer surface, in the form
of the stem and pileus, in the breadth and attachment of
the gills; and yet, amidst all, certain general features will he
preserved which preclude much difficulty, though they make
it extremely hard to draw up such characters as shall be generally
applicable. Notwithstanding all the experience which
the great Swedish Fungologist has had in the study of the
fleshy Fungi, and clever as his characters confessedly are, and
satisfactory taken as a whole, individual specimens constantly
occur, from local modifications, which cannot he comprised
within their limits. Nay, even generic and sectional characters
are sometimes at fault. I t is, for instance, frequently a
matter of difficulty to distinguish an Agaric of the subgenus
Tricholorna from one of the subgenus Clitocybe, because, though
one is distinguished by having the gills emarginate or siuuated
behind before their attachment to the stem takes place, and
the other has the gills acutely adnate without any emargiiia-
tion, modifications occur on either side; w'hile in Clitocybe,
in an early stage, there may be a decided emargiuation, in
Tricholorna, from the depression of the pileus, the gills may
become decurrent. And yet these characters are founded in
nature, and arc satisfactory enough when the variations to
which they are subject arc properly appreciated. Still more,
changes of outward form may occasionally take place, inconsistent
with the character of the species. Thus we may have
umbonate individuals where the pileus ought simply to he
obtuse, while a stemless Agaric may exhibit a stem or the
contrary. The fact, however, is, that as in phaenogamic
botany the sum of characters must be looked to, while it is
remembered that no definitions in natural history can be
strictly mathematical. Where species are very difficult to
distinguish, it is in general because forms are separated which
are too closely allied, an evil which is familiar enough to every
practical botanist, though apt to be overlooked or completely
ignored by the inexperienced or mere localists. The essential
characters are often the least superficial, and hence the young
botanist is apt to make mistakes, from confounding mere analogies
with affinities. Some Agarics of the subgenus Pratella,
for instance, would never be separated from others of the
subgenus Lepiota, without examining the nature of the spores.
These organs, moreover, sometimes differ in closely allied
species of such similar external characters, that it would be
impossible to distinguish them without having recourse to- the
microscope.
If there is difficulty about species, there is often far more
about genera. The characters in so natural a group are