THE PSATHYRELLA SUB-TYPE 3 



(6) The basidia are polymorphic, for they consist of four distinct 

 types, each type being distinguished from the other types by a 

 difference in length. The longest basidia belong to the first genera- 

 tion, the next longest to the second generation, the next longest to 

 the third generation, and the shortest to the fourth generation. 

 With difference in length of the basidia is associated a difference in 

 protuberancy of the basidium-bodies above the general surface of 

 the hymenium as defined by the outer walls of the paraphyses. 

 The first-generation basidia (the longest set) protrude farthest, the 

 second-generation basidia (the next longest set) protrude not quite 

 so far, the third-generation basidia (the next longest set) protrude 

 still less far, and the fourth-generation basidia (the shortest set) do 

 not protrude at all. 



The grouping of the basidia into four sets, each set having a 

 different degree of protuberancy beyond the general level of the 

 hymenium, is a unique feature, so far as the Aequi-hymeniiferae are 

 concerned, and one which serves to separate at once the Psathyrella 

 Sub-type from the four other Sub-types with which it is associated. 

 However, in the Inaequi-hymeniiferae (Coprini), the basidia are 

 usually dimorphic, and sometimes trimorphic or tetramorphic. 



(7) The basidia of the various generations are so crowded to- 

 gether that it often happens that the spores of the older and more 

 protuberant basidia more or less overstand the spores of the younger 

 and less protuberant basidia without touching them. This crowd- 

 ing of the basidia is only rendered possible without mishap to the 

 spores by the differential protuberancy of the bodies of the basidia 

 of successive generations. It permits of an increase in the number 

 of spores produced on any unit area of the hymenium and must 

 therefore be regarded as an important factor in fruit-body efficiency. 

 A similar crowding of the basidia is characteristic of all Inaequi- 

 hymeniiferae, i.e. of all the Sub-types of the Coprinus Type. 



(8) The paraphyses are relatively large and well-developed. 

 They are joined together laterally into a system of cells, which 

 constitutes a pavement through which the isolated basidia protrude. 

 Since successive generations of basidia develop their spores at 

 the same time, the paraphyses (sterile elements) are necessary as 

 space-making constituents of the hymenium. As space-makers 



