Sketch of the Class Fungi. 



285 



called stemless (apus) ; or if applied by its whole upper surface, 

 which is thence become inferior, it is called resupinate. 



The stem is dilated above into an organ of various forms, but usu- 

 ally orbicular or flabelliform ; which is called pileus, or, which is 

 better, hymenophorum, since this term is applicable to tribes whose 

 hymenium clothes a claviform or branched receptacle, not having 

 consequently the least resemblance to a hat. 



The hymenophore, which is membranaceous, fleshy, coriaceous or 

 corky, assumes the most different forms. Sometimes it is a sort of 

 convex, hemispherical, campanulate, ovoid, conical hat ; sometimes 

 depressed in the centre, and infundibuliform, or altogether plane, or 

 even with its border turned up (e. g. Agaricus, Boletus, Polyporus, 

 &c.) ; sometimes it forms simple or branched clubs (Clavaria) ; some- 

 times cup-shaped membranes {Exidia), or sinuous folds and plaits 

 (Tremella). In stipitate Hymenomycetes the pileus is always, even 

 when it becomes separable from it, an expansion of the flesh of the 

 stem, and composed of the same elementary cells, sometimes however 

 slightly modified. 



In Agaricini the pileus is horizontal, and bears beneath plates or 

 gills (lamella), whose central substance is formed by membraniform 

 processes (trama, dissepimentum, Fr., subhymenial tissue), which are 

 given off at right angles to this surface, and radiate from the centre 

 to the circumference : these plates are simple or equal when they are 

 of the same length, or compound when they are unequal in length ; 

 that is to say, when between two long gills there are other shorter 

 ones which measure only a third, a fourth, &c, of the radius of the 

 pileus. In this case Krombholz calls them didymous, tridymous, tetra- 

 dymous, or polydymous, as half, third, or quarter gills, &c, are in- 

 terposed. They are more or less close and numerous, thin or thick, 

 broad or narrow, straight or ventricose in their free edge : in re- 

 lation to the stem they are variously circumstanced, being some- 

 times fixed to it either by their whole breadth or by running down 

 the stem (decurrentes) ; or they are attached by a less portion than 

 the whole breadth, in consequence of their being rounded off at the 

 point of attachment ; or, before they attain this point, there is a por- 

 tion cut out as it were, in which case they are said to be sinuate. 

 The free or lower border of the gills is entire or toothed, straight or 

 ventricose, equal or undulated, acute or obtuse, sometimes channel- 

 ed or cleft longitudinally, as in Trogia and Schizophyllwn. As re- 

 gards consistence, they are fleshy, membranous, coriaceous, watery, 

 milky, flexible, or brittle, &c. Their colour is very variable, and 

 presents every shade of white, black, rose-colour, violet, brown, &c. 

 Lastly, they are persistent or deliquescent, as in Coprinus. In the 

 genus Montagnites (Agaricus radiosus, Pall.) not only are they per- 

 sistent, although they become black, but, which is very remarkable, 

 they remain still fixed by a short filament round the top of the stem 

 after the destruction of the hymenophore. In Cantharelli the gills 

 are so narrow that they are reduced to simple dichotomous or 

 branched folds. In Merulius these folds anastomose and form a net- 

 work, which indicates a passage from Agaricini to Polyporei. 



