MUSHROOMS AND TOADSTOOLS 233 



the gills. As the pileus expands the membrane becomes detached first 

 at the margin of the cap, and it falls down around the stipe, as a frill, 

 plaited in delicate folds, corresponding to the former lines of contact 

 with the lamellae and is now known as the annulus superus, frill, or 

 armilla. Special milk tubes are found in such forms as species of Lac- 

 tarius for when these toadstools are wounded a milky fluid oozes out in 

 drops. Each basidium usually bears four basidiospores, sometimes 

 thereare two. The color of these spores is distinctive, and is used in 



Fig. 93. — Deadly amanita (Amanita mitscaria) showing volva at base of stem 

 and frill, like stem ring. {After Chestnut, V. K., Bull. 175, U. S. Dept. Agric, pi. i, 

 Apr. 29, 1915-) J 



the classification of the genera of the family. We distinguish the 

 white-spored, rosy-spored, ochre-spored (yellow or brown), brown- 

 spored, black-spored agarics. 



Buller in his "Researches on Fungi" (1909) has carried on detailed 

 studies with numerous species of gill fungi and has studied the physi- 

 ology and mechanics of spore discharge and fall. The disposal of the 

 hymenium beneath a pileus on gills, the rigidity of the fruit body, the 

 growth movements of the fruit body, all faciUtate the distribution of the 

 discharged basidiospores. The spores liberated from a pileus in per- 



