2 RESEARCHES ON FUNGI 



type is exceptional for the Aequi-hymeniiferae. It is true that, in 

 the Bolbitius Sub-type, the fruit-bodies are also ephemeral ; but, 

 in the Armillaria, the Inocybe, and the Panaeolus Sub-types which 

 contain most of the Aequi-hymeniiferae, the fruit-bodies are per- 

 sistent, i.e. they last longer than one day after commencing to shed 

 spores, and their spore-discharge period varies from a few days to 

 a week or even longer. As examples of these persistent species, 

 which contrast with the ephemeral Psathyrella disseminata and 

 Lepiota cepaestipes, may be mentioned : Panaeolus campanulatus 

 which sheds spores in the laboratory for from 7 to 11 days, Psalliota 

 campestris which sheds spores for from 5 to 6 days, Marasmius 

 oreades, Armillaria mellea, Russulae and Lactarii. 



Let us now consider in detail the special characters of the Psathy- 

 rella Sub-type. These are as follows : 



(1) The whole structure of the fruit-body is relatively light and 

 suited to a brief duration of the pileus. 



(2) The spore-discharge period is very brief, its length varying 

 from 12 to 24 hours. 



(3) The gills are not mottled and there are no waves of develop- 

 ment passing over the hymenial surface : the hymenium develops 

 everywhere in a very even manner. In this respect we have a 

 distinct contrast with the Panaeolus Sub-type. 



(4) The number of generations of basidia on the hymenium is 

 limited to three or four. In the Panaeolus Sub-type there are at 

 least eight such generations and probably ten or twelve. 



(5) On any small area of the hymenium, the basidia of one 

 generation do not wait to develop spores until the basidia of the 

 previous generation have discharged their spores : there is over- 

 lapping in development. The second-generation basidia begin to 

 develop spores some hours before the spores of the first-generation 

 basidia have ripened and have begun to be discharged. The third- 

 generation basidia behave to the second-generation basidia, and the 

 fourth to the third, as the second to the first. The spores of the 

 fourth-generation basidia may be in course of development before 

 the spores of the first-generation basidia have all been discharged. 

 This overlapping in the development of the successive generations 

 of basidia does not occur in the Panaeolus Sub-type. 



