A MUSHROOM 



8S 



of most of the mushrooms, bears four spores. The fmiting 

 body of Fomes hves and grows from year to year, forming new 

 spores each year. But the fruiting bodies of some other 

 bracket fimgi, such as the sulphur mushroom, a large, vellow, 

 quickly growing form that is soft and edible when young, 

 die after bearing one crop of spores. The branching threads 

 that make up the vegetative body of a bracket fungus Hve 

 in the tissues of the trees upon which the fruiting body 

 appears. ]\Iany species of bracket fungi live on dead trees ; 

 they are saprophytic. But 



others are parasitic ; they .■^/'^^'^^^^^'% 



enter the host tree through 

 wovinds, cause a decay of 

 the wood, and finally kill 

 the tree. 



113. Puffballs (Fig. 42). 

 — These are still another 

 class of basidium fungi 

 whose basidia are entirely 

 enclosed within a rounded 

 mass of tissue which either 

 Hes close to the ground or 



is raised upon a short stalk. The largest of the group is 

 the " giant puffball," specimens of which sometimes reach a 

 diameter of one and one-half or two feet. When young, 

 the flesh of this puffbaU is firm and white, and it is then 

 edible. As it grows older, the inner part becomes darker 

 because of the formation and ripening of the spores. Finally 

 the interior consists of a mass of dark-brown or black spores 

 which escape through cracks in the wall of the ptiffbaU. 



Fig. 42.- 



A puffbaU [Scleroderma 

 vulgare). 



