6 



(The Tuberacei comprise a very small group of subterranean fungi, and 

 comparatively few of the species are described.) 



Saccardo in his Sylloge gives a total of 42,000 described species of 

 fungi of all classes, including the most minute. Of these the Hymeno- 

 mycetes include by far the largest number of edible mushrooms. 



The family Hymenomycetes is divided into the following six orders : 

 Agaricini, Polyporei, Hydnei, Thelephorei, Clavarei, Tremellini. 



In the order Agaricini the hymenium is found on the under surface of 

 the mushroom cap, covering pleats or gills, technically called lamellae. 

 These gills vary in character in the different genera, being " persistent in 

 such as the Agaricus, Russula, and Leutinus, deliquescent (melting) in 

 Coprinus, Bolbitius, etc. The edge of the gills is acute in Agaricus, Ma- 

 rasmius, etc., but obtuse and vein-like in Cantharellus, longitudinally 

 channelled in Trogia, and splitting in Schyzophyllum." 



In the Polyporei, pore-bearing milshrooms, the gills are replaced by 

 tubes or pores. The tubes are little cylinders, long or short, pressed one 

 against another, forming by their union a layer on the under surface of 

 the cap, and the sj^oriferous membrane or hymenium lines their inner 

 walls. Their upper end is always closed, while the lower extremity is 

 open to permit the outward passage of the sj)ores. The tubes are gen- 

 erally joined together and are not easily disunited. They are free, i. e., 

 separable, in the sole genus Flstulina. As regards their attachment to 

 the cap, the tubes may be firmly adherent as in the genus Polyporus or 

 easily detached in a single ma^ as in Boletus, the fleshy form of the order 

 Polyporei. They frequently leave a circular space of greater or less di- 

 mensions around the stem, or they adhere to or are prolonged upon it in 

 such a manner that the orifices rise in tiers one above another. The 

 color of the tubes, although not offering as characteristic varieties as 

 that of the gills, changes nevertheless according to species and according 

 to the age of the plant. The tubes may sometimes be of a different color 

 from their orifices, as in Boletus luridus. In some of the Boleti the color 

 of the flesh is changed on exposure to the air and the tubes often assume 

 the same tints. The tubes, generally called pores, are sometimes closely 

 adherent to the substance of the cap, which is often hard, corkj^, or cori- 

 aceous, as seen in most of the l^olyporei. 



In the Hydnei, spine-beari]ig mushrooms, the hymenium is seen cover- 

 ing the spines or needle-like processes which take the place of gills in this 

 order, and which project from the under surface of the cap. These 

 spines may be divided or entire, simple or ramified, and are formed of the 

 substance of the cap. lu the early stages of development they appear 

 like small projecting points or papillae, those on the margin of the cap 

 and at the apex of the stem being always less developed, frequently re- 

 maining iu this rudimentary state. They are rounded in the species 

 Hydnum imbricatum, sometimes compressed in Hydnum repandum, some- 

 times terminating in hairs or filaments, as in Hydnum barba Jo vis, or very 

 much divided, as in Hydnum fimbriatum. 



