PSALLIOTA CAMPESTRIS 377 



from the gills being thus upwardly inclined instead of remaining 

 with their long axes directed horizontally lies in the fact that the 

 vertical distances between the gills through which the spores 

 (especially those li berated near the tops of the gills) have to fall 

 are thereby increased, and that with these increases there is 



FIG. 134. Psalliota campestris, wild form obtained in a pasture at Banbury, Eng- 

 land. Sections through fruit-bodies to show the appearance of the gills at 

 different ages. In C, where the gill-chamber is as yet unruptured, the surface 

 of the gills has an even appearance. In A, where the pileus is expanding, the 

 surface of the gills is faintly mottled. In B, where the pileus is fully expanded, 

 the gills are very distinctly mottled. Natural size. 



increased risk that the spores in passing down the very narrow 

 interlamellar passages will touch the gill-sides and adhere to them ; 

 but there is a distinct advantage gained, namely, that the gills as 

 a whole, and therefore also the basidia, are raised an appreciable 

 part of an inch. This extra elevation, obtained by sacrificing to 

 a slight extent what we considered to be the ideal form of the pileus, 

 permits of the free space beneath the gills being increased in depth, 

 with the result that the wind has so much the better chance of 

 carrying off the spores. 



