28 RESEARCHES ON FUNGI 



fruit-body, when i^^ills, tubes, or spines have been removed. Let 





Fig. 4. — Fiuit-body of Poli/porux st/ditnwxus ucarly full-grown ; upper surface covered 

 with brown scales. The full length of the stipe is photographed. Photographed 



by R. H. Pickard. 



I natural size. 



H be the area of the hynieniuiu upon the uills, tubes, or spines. 



H 



Then the ratio . gives the increase of surface of the hynienium 



