CRYPTOGAMS 



411 



pili'iis, which may bo 20 cm. wide, is yellowish-brcnvn on its upper surface, but on 

 tin- iiii<lt'v side is at first blood-red, becoming later orange-red. Of the numerous 

 spi-cics of the genus Polyporus, P. fomcntarius, Touch-wood, is used in medicine. 



Km. :r.8.--7W///i/-.< tffniaritu. Si-ction through an old 

 frustification, showing annual /ones of j^'owth ; a, 

 liciint of attachment. (J nat. .size.) 



Fio. 359. Pmlliota eamjientria ( = Aga- 

 rlciis campestris). To the right, a 

 yonnj; t'l uctiliraticm. (Reduced.) 



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, grey external surface, but inside are composed of softer, 



Km. 3i>0. 



* Sutunrtx. (After KROMBHOLZ, A nat. size.) 1'OISOXOCS. 



more loosely woven hyphse, and were formerly used for .tinder. The narrow tubes 

 of the hymenium are disposed on the under side of the fructifications in successive 

 annual layers. /'. iij/t.-iarivs (Fig. 358), which is often found on Willows, and has 

 a similar structure, has a rusty-brown colour, and furnishes, since it is much harder, 

 a poorer quality of tinder. Polyporus officinalix with an irregularly tuberous 



