Journal of Proceedings. lxxi
the spores are formed. As soon as the spores are ripe they detach
themselves from the tips of the sterigmata and fall off; the cell that
produces them (or basidium) then contracts and makes room for other
cells to push forward and repeat the process. Now if you take the pileus
of any vigorous-growing Fungus, such, for instance, as Agaricus melleus,
two hundred of which sprung up in a couple of days on a corner of
the lawn at a place in Dorsetshire, where I was staying last month, and
if you put one of the caps under a cover in the manner I have described,
you will notice in the course of half an hour a hoary deposit on the
black paper on which it is placed. In the course of the night a deep
coating will have been thrown down giving a plan of the gills ; if you
measure these spores you will find their size to be .0004 by .00025 of an
inch (10.159 μ by 6.349 μ). An easy calculation will show that a square
inch of surface covered closely will contain 10,000,000 spores. Taking
for granted that in the nine hours of night a deposit of ten deep has
been shed, and this is probably within the mark, you find that
100,000,000 spores have been thrown down on each square inch of the
paper covered by the pileus. A moderate-sized pileus of this Fungus
will cover an area of about six square inches. So here you have a single
Fungus which in less than half a day has produced 000,000,000
spores, each, as far as we know, capable of germinating and forming a
fresh mycelium, if it should fall on a suitable soil. Fortunately for
us, such a soil is not often at hand, or the country would present in
autumn only one vast field of Agaricus melleus. I have calculated the
deposits of other Fungi, which give far larger results than these. I may
add that from a single pileus you may continue to take a series of these
patterns for three or four days consecutively without any apparent
diminution in the rate of spore production.
I now come to the mode of preserving white spores; these for a long
time gave me trouble, from the difficulty in obtaining a black paper
sufficiently porous to allow the gum water to penetrate. Without
wearying you with an account of a series of failures, I can at least
give a process which I find perfectly successful. If you procure dull
black paper (black on one side only), which can be had at most
stationers, you find it as a rule entirely impervious, but if it is steeped
for four or five hours in a solution of one part of nitric acid to ten of
water, then taken out and allowed to soak in distilled or rain water for
five hours, the water being changed two or three times until all trace of
acid has been removed, and then dried, you find that all gelatinous
matter has been removed from the paper and gum water will penetrate
it with ease. Even here, however, your difficulty is not quite at an end,
for with spores of Lactarius and Russula and all such fungi as have
prickly spores, although the gum water passes through the paper it will
not permeate the spores, and they will brush off as if no application had
been made ; but if instead of gum you wash the back of the paper with
Canada balsam dissolved in benzine in a weak solution, even the prickly
spores will be firmly set, but they should be carefully dried before
applying the solution, as, if moisture remains, it hinders the process.
It is curious that this method is not generally successful with smooth
spores, though it is in some cases, but the result of experiment on a
variety of species leads to the conclusion that gum is best for setting all
spores, except prickly spores on black paper, where the solution of balsam
succeeds and gum does not.
I have hitherto referred only to the mode of preserving the spores of
gilled funguses, but the same process answers equally well for those
provided with tubes in place of gills, and as these present great
variety in different species, it is a very useful addition to your drawings