PSATHYRELLA DISSEMINATA 



39 



all arisen directly on the sides of the inverted stump at and just 

 above the surface of the ground, would have been very much 

 crowded, and a large number of them would not have been able to 

 shed their spores with any good chance of their being disseminated 

 by the wind. As it was, the fruit-bodies arose at the surface of the 

 soil upon the subterranean ozonium. In consequence of this, the 



Fig. 22. — Psathyrella disseminata. Some fruit-bodies springing from the mortar 

 of a brick wall of a green-house at the Priory, Kew. A, sketch showing the 

 outside of the wall : a, bricks covered by garden soil. B, a section through 

 the wall : a, garden soil ; b, soil in green-house ; c, wood-work in green-house, in 

 wliich, presumably, the mycelium of the fungus was growing. The secondary 

 mycelium or ozonium, doubtless, penetrated the wall via crevices in the mortar 

 and then gave rise to the fruit-bodies in the position shown. 



^'^ natural size. 



space for the development of the numerous fruit-bodies was greatly 

 extended. Further, the spore-producing pilei were removed to a 

 small distance from the sides of the stump, and thus the wind was 

 given a better chance to carry off the spores. Evidently, although 

 fruit-bodies can be, and often are, developed directly on the surface 

 of the bark or wood of stumps, the production by the fungus of 

 soil-penetrating ozonium gives greater freedom in the choice of the 

 positions of origin of the fruit-bodies and, consequently, brings an 

 advantage to the .species so far as the dispersion of the spores is 

 concerned. 



The fruit-bodies of Psathyrella disseminata sometimes occur in 



