THE ANATOMY OF A MUSHROOM, 
397 
the basidia, and pass from the latter to the former through the 
slender tubular sterigmata during the growth of the spore. At 
first the apices of the sterigmata swell and assume the form of 
small, round tubercles. For a long time the spherical shape is 
maintained, but at length the form peculiar to the species, 
whether ovoid, elliptical, angular, or cylindrical, is established, 
and in some kinds the surface is covered with asperities, whilst 
in the majority it is smooth (fig. 9). 
When the spores are mature their colour is comparatively 
constant in the same species. So much is this the case that 
the colour of the spores is employed to divide the different 
species of agarics into five groups or series. In one of these 
the spores are colourless, or white when seen in a mass. In 
another they are salmon-coloured. In a third series they are 
rusty, tawny, or brownish. In a fourth — to which the common 
mushroom, and the meadow mushroom {Agavicus arvensis) 
belong — the spores are of a brownish-purple or brown. And 
in the fifth series they are black, or nearly so. The spores 
being matured fall from the basidia upon the ground beneath 
the pileus. So profuse are the spores in some species, that, espe- 
cially when white, they seem wholly to cover the surface imme- 
diately beneath. That very common species {Agaricus melleus), 
which grows in large tufts on old stumps, is a familiar example 
of the profusion of spores which may be evolved from a single 
fungus. In this instance the ground, or any intervening object, 
is rendered as white as if sprinkled with flour or powdered 
lime. 
The most obscure period in the life history of an agaric, and 
some other fungi, is that which intervenes between the mature 
spore and the young plant. We see the spores fall to the 
ground in profusion : from myriads of spores perhaps the same 
spot does not the next season supply us with a single fungus. 
We collect the spores of species after species, and try by all 
known processes to force them to germinate, but it is fruitless. 
Their behaviour is, to all appearance, that of unfertilised ova, 
of unimpregnated germs. What are the conditions which 
agarics require in order to render their spores fertile? We 
know something of one species, and of one only ; but even that 
is accidental, and we cannot give a logical reason. The great 
difficulty in the way of cultivating other esculent species is that 
of ascertaining the requisite conditions for the germination of 
the spores. Here is a good field for investigation and experi- 
ment, and there is no doubt that if persevered in such efforts 
would produce results calculated to bring us nearer to the com- 
prehension of this mystery, which is at present wholly a mystery, 
such as involves no other members of the vegetable kingdom. 
It is possible that spermatia may yet be traced where they are 
