THE SPORE AND ITS DISSEMINATION. 121 
are distributed over the hymenium or gill plates, the surface of 
which is studded with basidia, each of which normally ter- 
minates with four short, erect, delicate, thread-like processes, 
each of which is surmounted by a spore. These spores are 
colourless or coloured, and it is upon this fact that primary divi- 
sions in the genus Agaricus are based, inasmuch as colour in the 
Fic. 45.—Spores of (a) Agaricus mucidus; (hb) Agaricus vaginatus; (v) Agaricus 
pascuus; (d) Agaricus nidorosus, (€) Agaricus campestris. (Smith.) 
spores appears to bea permanent feature. In white-spored species 
the spores are white in all the individuals, not mutable as the 
colour of the pileus, or the corolla in phanerogamic plants. So 
also with the pink spored, rusty spored, black spored, and others. 
This may serve to explain why colour, which is so little relied 
upon in classification amongst the higher plants, should be intro- 
duced as an element of classification in one of the largest 
genera of fungi. 
There are considerable differences in size and form amongst 
the spores of the Agaricini, although at first globose; when 
mature they are globose, oval, oblong, elliptic, fusiform, and 
either smooth or tuberculated, often maintaining in the different 
Fic. 46.—Spores of (a) Lactarius blennius; (b) Lactarius fuliginosus ; (c) Lactarius 
quictus, (Smith.) 
genera or subgenera one particular characteristic, or typical 
form. It is unnecessary here to particularize all the modifica- 
