SECT. I 



CRYPTOGAMS 



413 



poisonoiis, in particular B. Satanas (Fig. 3-17). The stalk of the latter fungus is 

 a yellow to reddish-purple, or has red reticulate markings, while tlie pileus, which 

 may be 20 cm. wide, is yellowish-brown on its upper surface, but on the under side 

 is at first blood-red, becoming later orange-red. Of the numerous species of the 

 genus Polijj}07'us, P. fomentarius, Touch-wood, is used in medicine. Its mycelium 

 is parasitic in deciduous trees, especially the Beech, and produces large, bracket 

 or hoof-shaped, perennial fructifications, 30 cm. wide and 15 cm. thick. They 

 have a hard, grej^ external surface, but inside are composed of softer, more loosely 

 woven hyphae, and were formerly used for tinder. The narrow tubes of the 

 hymenium are disposed on the under 

 side of the fructifications in succes- 

 sive annual layers. P. itjniarius 

 (Fig. 348), which is often found on 

 Willows, and has a similar structure, 

 has a rusty-brown colour, and fur- 

 nishes, since it is much harder, a 

 poorer quality of tinder. Polyparus 

 officinalis, with an irregularlj' tuber- 

 ous white fructification, occurs on 

 Larches in South Europe ; it con- 

 tains a bitter resinous substance 

 and is also used in medicine. 



ilany parasitic Polyporeae are 

 highly injurious to the trees attacked 

 by them ; thus Heterohasidion an- 

 nosum often causes the death of 

 Pines and Spruce Firs. Merulius 

 lacrymans (^) is an exceedingly 

 dangerous saprophytic species only 

 rarely found wild in woods, but 

 attacking and destroying the timber 

 of damp houses, especially coniferous 

 wood. The mycelium of this fungus 

 forms large, white, felted masses 

 with fii'mer branched strands which 

 serve to conduct water and food sub- 

 stances. It gives rise to outspread, irregularly shaped, pitted fructifications of an 

 ochre or rusty-brown colour, and covered with a hymenial layer. Good ventilation 

 of the infected space and dryness are the best remedial measures. 



6. The Agaricineae, which include the greatest number of species, have stalked 

 fructifications, commonly known as Mushrooms and Toadstools. The under side of 

 the pileus bears a number of radially disposed lamellae or gills which are covered 

 with the basidia-producing hymenium. In the early stages of their formation the 

 fructifications consist of nearly splierical masses of interwoven hyphae, in which 

 the stalk and pileus soon become ditt'erentiated. The rudiments of the stalk and 

 pileus are at first enclosed in a loosely woven envelope, the volva. In the course 

 of the further development and elongation of the stalk the volva is ruptured, and 

 its torn remnants form a ring or sheath at the base of the stalk, and in many cases 

 (as in the " Fly Mushroom," Amanita muscaria) are still traceable in the white 

 scales conspicuous on the red surface of the pileus (Fig. 350). In addition to the 

 volva many Agaricineae develop a so-called velum, consisting of a thin membrane 



Fk;. 3u0. — Amanita muscaria. (J iiat. size.) Pojsoxocs. 



