418 



According to Professor Biiller, of the University of Manitoba, a sin- 

 gle large specimen of the cultivated mushroom, or meadow mushroom, 

 Agariciis caiiipcstris, may produce as many as 1,800,000,000 spores, 

 vhile a large shaggy-mane mushroom has been estimated to produce 

 5,240,000,000 spores. But some other kinds of mushrooms do even 

 better, since a single giant puffball may produce as many as 7,000,000,- 

 000,000 spores. Of course such a production allows for an immense 

 waste, and it is probable that not more than one in 20,000,000, and 

 perhaps much fewer than that, ever succeeds in growing. 



Fig. 1. Cross-section of a very small portion of a gill, showing hyphae, aj basidia, 

 1) ; spores, c; and a cystidium, d. Greatly enlarged. 



When the spores are mature they are discharged forcibly from the 

 basidia. They are projected outward at right angles to the surface of 

 the gill for a distance ecjual to something less than one-half the dis- 

 tance between two adjacent gills. This gives them a clear pathway 

 to fall downward. 



Certain kinds of mushrooms have a special means of making sure 

 of the proper liberation of their spores. In the shagg\-mane mush- 

 room (page 479), for instance, and in others belonging to the same 

 group, the gills are very close together, but at maturity they deliquesce 

 or dissolve into an inky fluid. This is in no sense comparable to 

 the dissolving of chemical substances, but is a process of auto-digestion 

 (self -digestion). The spores on these gills mature in a very definite 

 order, beginning at the lower ends of the gills and ripening progres- 

 sively upward. As the cap begins to open up and becomes bell-shaped, 

 the lower ends of the gills are slightly separated from each other. 



