PSALLIOTA CAMPESTRIS 369 



become evenly occupied by the mycelium and all further ring- 

 formation would be rendered impossible. The inevitable conclu-. 

 sion from this argument seems to be, therefore, that the spores of 

 Psalliota campestris, Marasmius oreades, Clitocybe gigantea, and of 

 other ring-forming fungi occurring in pastures, even when scattered 

 in prodigious numbers over fields where the turf is capable of 

 supporting the mycelium, rarely succeed in causing infection. The 

 reasons for the enormous waste of spores under these conditions 

 require further elucidation. 



External Appearance of a Fruit-body. The following descrip- 

 tion of the fruit-body of Psalliota campestris includes the field 

 characters only. It has been compiled, in the light of my own 

 observations, from the descriptions given by Fries, Berkeley, 

 Greville, Stevenson, Massee, and Atkinson, with the object of com- 

 bining fulness with accuracy. For illustrations of the fruit-bodies 

 of the wild Mushroom, as found in pastures, the reader is referred 

 to Figs. 129 and 134 (pp. 362, 377) in this Chapter and to Figs. 9 

 and 17 in Volume I (pp. 36 and 51). 



The pileus is 5-13 cm. broad, at first rounded but, as expan- 

 sion takes place, its top becomes first convex and then flat. The 

 surface is at first smooth, presenting a soft, silky appearance from 

 numerous loose fibrils, but later it is sometimes torn into triangular 

 scales, especially as the fruit-body becomes old. The colour is 

 usually white, but varies more or less to light brown, especially in 

 the scaly forms where the scales may be quite prominent and dark 

 brown. Sometimes the colour is brownish before the scales appear. 

 The flesh is firm, thick, white, often more or less stained with 

 reddish-brown, especially when bruised. The pellicle is extended 

 slightly beyond the margin of the pileus and can be easily separated 

 from the subjacent flesh. 



The gills are free but rather close to the stipe, 0-6-1-6 cm. 

 broad in the middle, of various lengths, closely set together so that 

 the interlamellar spaces are narrow ; the longest gills are equally 

 attenuated at both ends and ventricose. The colour of the gills 

 in the button stage of the pileus is white, but at the time of 

 expansion it is a beautiful pink. As the pileus becomes older 

 and more and more expanded, the pink changes successively 



