FUNGI. 



463 



nparly so, underground, and that part which is commonly called the 

 fungus is the receptacle. 



The Agaridni are distinguished from the other Hymenomycetes by the 

 hvmenium being always interior, and spread over the surface of gills 

 which radiate from the stem. The gills may be either simple or branched, 

 and attached to or distinct 



Fig. 515. 



The Mushroom (Agarious campestris) : A. Fruit, 

 showing the expansion from the volva, and the 

 veil tearing away and leaving the annulua. 



B. flection of " gills," magnified 50 diameters. 



C. Basidia and spores from ditto, magn. 400 

 diam. 



or 



from the stem. The spores 

 vary in colour ; but one colour 

 is constant as a rule to a genus, 

 unless in the case of the large 

 genus Agaricus, where the 

 colour of the spores is used as 

 the basis in forming groups of 

 the different subgenera. The 

 stem is sometimes cartilagi- 

 nous, and sometimes fleshy, 

 and also varies in colour, but 

 according to the species and 

 even to its age. There is to 

 be found on the stem in some 

 genera and subgenera a ring 

 or annulus, which is all that 

 remains of a veil or covering 

 (velum partiale) which united 

 that part of the stem with 

 the outer edge of the cap or pileus, but was ruptured on the expansion 

 of the latter. In certain subgenera of Agaricus (e. g. Volvaria, Amanitd) 

 the whole fungus is enclosed at first in a volva (velum universal*), which 

 on bursting falls away and is independent of the cuticle on the upper suiv 

 face of the pileus, but remains attached to the base of the stem. Some- 

 times, as in Amanita, both forms of veil are found together. The s+em. 

 is not always central, but is also found to be eccentric and even lateral, 

 as in Pleurotus, in which it is usually very much suppressed. There are 

 more esculent species of Agaridni than of any other group of Fungi. 

 The species are usually terrestrial in habit. 



In the Polyporei the hymenium is spread over the cavity of tubes or 

 pores, and is in some cases inferior and in others superior. The texture 

 of the plants is, as a rule, more cartilaginous and woody than that of the 

 Agaridni. The genus Boletus has the habit of an Agaric, and usually 

 its central stem and texture. The hymenium is distinct from the hymeno- 

 phore, from which the tubes are easily separated. The genus Polyporm 

 is, on the other hand, different from the Agaridni in habit the stem 

 when present being usually lateral, and the texture of the whole often 

 very woody. The hymenophore is not easily separated from the pores. In 

 the resupinate forms the pores open upwards, and the habit of the fungus is 

 crust-like. The species of this genus grow, as a rule, on stumps of trees 

 and other woody substances. 



The hymenium of the Hydnacei is inferior or amphigeous, and spread 

 over teeth or spines, which are soft, usually of the shape of an awl, and 

 distinct at the base. Some of the species are in the form of a stalked 

 pileus with the teeth on the under surface, while others resemble the 



