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 



Fio. 45. Spores of (a) Agaricus mucidus; (b) Agaricus vaginatus ; (c) Agaricua 

 pascuus; (d) Agaricus nidorosus; (e) Agaricus campestris. (Smith.) 



spores appears to be a 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 



Fio. 46. Spores of (a) lactarius blennius; (b) Lactarius fuliginosus; (c) Lactariut 

 quietus. (Smith.) 



genera or subgenera one particular characteristic, or typical 

 form. It is unnecessary here to particularize all the modifica- 



