164 



BASIDIOMYCETES. 



as a number of fine holes. The fruit-body most frequently resembles a bracket, 

 or is hoof-shaped, with one side growing from a tree-trunk ; it is very often per- 

 ennial, and a new layer of tubes arises in each succeeding period of vegetation. 

 Strata, corresponding to the periodically interrupted growth, are thus formed in 

 stories one above the other, and are visible on the upper surface of the fruit- 

 body, as well as in the interior, as a series of concentric belts, sometimes as 

 many as half a score or more in number. P. fomentarius (Touchwood) attacks 

 trees, especially the Beech. The spores germinate on wounds from broken 

 branches, and the hyphae, following the course of the medullary rays, find their 

 way into the interior of the tree, from whence the mycelium spreads upwards, 

 downwards, and peripherally, so that the wood becomes rotten (" wh te-rot") 

 and thick felts of mycelium are formed iu radial and tangential directions. A 



dark line, caused by the 

 youngest parts of the hy- 

 phffi containing a brown 

 juice, marks the boundary 

 between the rotten and 

 the unattacked parts of 

 the stem (Fig. 168); at 

 places where the mycelium 

 extends to the bark, the 

 cambium becomes de- 

 stroyed and further growth 

 is arrested, so that longi- 

 tudinal furrows arise on 

 the stem. It is at these 

 places, too, that the boof- 

 shaped, ash - coloured 

 fruit-bodies are developed, 

 which may attain a cir- 

 cumference of upwards of 

 7 feet. The interior of 

 the fruit-body consists of 

 a dried-up, loosely felted, 

 red-brown mass of hyphas, 

 which has been used for 

 tinder and as a styptic 

 ("Fungus chirurgorum"). 

 P. igniarius has a harder, 

 dark-brown, more rounded 

 fruit- body ; it grows in a 

 similar manner, but 



especially attacks Oaks, Poplars, and Plum-trees, the wood of which becomes 

 rotten, and is called touchwood. P. plni (Trametes pint), (Fig. 170), a parasite 

 on the stems of Pimts, causes a kind of " red-rot " in the stem. P. sulphureus 

 has a soft, cheesy, yellow fruit-body; it produces " rot" in Oaks and Apple- 

 trees. P. ojllcinalis, Larch-fungus (" Fungus Laricis " in Pharmocopoeia), grows 

 on Larch- tr<.es in the south-east of Europe. P. versicolor has thin, semicircular 



FIG. 107. Polyporus igniarius. Section through the 

 under side of the Fungus : h-h is hyphal-tissue between 

 the tubes, formed by irregularly felted hyphse, many of 

 which are seen cut across; s is the hymenium which 

 covers the walls of the tabes, and from which the basidia 

 with the spores protrude. 



i 



