PANAEOLUS CAMPANULATUS 245 



half of the development of each spore, the hymenial mosaic- 

 work is mottled. The mottling can be seen with the naked eye. 

 The areas with the more advanced spore-bearing basidia are rela- 

 tively dark, and the areas with the less advanced spore-bearing 

 basidia relatively light. The basidia in any small area of the 

 hymenium come to maturity in a series of sharply defined succes- 

 sive generations. A dark area becomes a light area as soon as the 

 spore-bearing basidia, which are approximately equal in their 

 state of development, have shed their spores. The light area so 

 produced remains light until the basidia of a new generation have 

 advanced so far in development that their spores are beginning to 

 be pigmented. The light area then turns dark again. The alterna- 

 tion of darkness and lightness in an area continues until all the 

 generations of basidia have come to maturity and the hymenium 

 is exhausted. The spore-bearing basidia on any dark or light 

 area are closely packed together side by side. All the basidia of 

 the hymenium are monomorphic, i.e. when they reach maturity and 

 are bearing spores they all project to an approximately equal 

 distance beyond the general surface of the hymenium. 



Mottling of the gills is a striking macroscopic colour-indication 

 of the mode of organisation of the hymenium and, where it occurs, 

 serves to distinguish the Panaeolus Sub-type from all the other 

 Sub-types. 



Panaeolus campanulatus : General Remarks on the Sporo- 

 phore. This species was chosen for detailed study for the follow- 

 ing reasons. Its fruit-bodies (Fig. 83) possess hymenial elements 

 sufficiently large for convenience of observation, black spores of 

 considerable size (the three dimensions being 13-14 X 9 X 6-7 p), 

 and thin transparent gills. The fungus is coprophilous and can 

 be easily cultivated from spores on sterilised horse dung. Upon 

 this medium, at ordinary room temperatures, it can pass through 

 the whole of its life-history from spore to spore in five weeks. By 

 making artificial cultures in the laboratory I was able to obtain a 

 constant supply of fruit-bodies all through the Manitoban winter 

 a period of severe frost, lasting five months, during which not a 

 single fleshy agaric of any kind can be gathered in the open. The 

 sporophores of Panaeolus companulatus are also of suitable size 



