SECT. HI. AGARICIN1. 261 



cetes and the Physomycetes. These various groups we 

 may now proceed to examine. 



The most important family of Fungi is, without ques- 

 tion, that of the HYMENOMYCETES, the species of which 

 far excel all others in their richness of colouring, and 

 beauty of form. In this group the hymenium is free 

 and mostly exposed. It comprises six orders, of which 

 the Agaricini hold the first place. The genus Agaricus 

 alone comprises 1,000 distinct species, which assume as 

 many different forms and colours, with only slight mo- 

 difications of substance, and it surpasses in number of 

 species all the other generic groups known. 



The Agaricus campestris, or common mushroom, is a 

 type of that vast group ; it consists of two distinct parts, 

 the nutritive and reproductive. The nutritive part is 

 the mycelium or mushroom spawn of gardeners, which 

 resembles a mass of white spider's threads mixed in 

 inextricable confusion, and carries on for a time all the 

 functions of the plant. Mycelia may exist for years 

 without bearing the reproductive part, but fruit never 

 can be produced without spawn. The mushroom itself, 

 which springs from the spawn, is the fruit-bearing part, 

 in which the spores are formed and ripened. It is dis- 

 tinguished by a kind of hat or bonnet called the pileus, 

 supported by a stem. The pileus is lined by a number 

 of gill-shaped plates or lamellae radiating from a com- 

 mon centre ; they are the reproductive organs in which 

 the spores are produced by free cell formation, a process 

 always preceded by a concentration of the matter within 

 the parent cell, which is then divided into as many 

 nuclei as there are to be spores. In the higher fungi, 

 the number of spores thus formed is definite ; in the 

 Agarics they are in groups of four placed at the ex- 

 tremity of a stem, springing from the summits of these 

 reproductive gills. Most of the Agarics rise from the 



