PSATHYRELLA DISSEMINATA 59 



similarity of these hairs in Psathyrella disseminata and Coprinus 

 curtus, etc., was demonstrated by Knoll i), and (6) the occurrence on 

 top of the pileus of a certain number of loose spherical cells more 

 or less aggregated into scales (there are but' few of these loose cells 

 in Psathyrella disseminata but they are quite similar in their nature 

 to those which make up the tiny scales in Coprinus curtus and the 

 more bulky mealy covering of Coprinus niveus and C. stercorarius). 

 To these resemblances which concern the fruit-bodies we may add 

 certain others which have to do with the mycelium. Psathyrella 

 disseminata and certain of the Coprini, e.g. Coprinus domesticus, 

 have (7) the same kind of habitat, namely, bark and wood, for they 

 grow about dead roots and tree stumps. Moreover (8) these two 

 species both produce an ozonium. 



From what has been said in the foregoing paragraphs, I think 

 that there can be no doubt that Psathyrella disseminata and many 

 of the smaller Coprini have been evolved from a common stock 

 and are nearly related. Without much difficulty, one can imagine 

 a Coprinus arising from the Psathyrella or the Psathyrella from a 

 small Coprinus. To change Psathyrella disseminata into a Coprinus 

 it would only be necessary : (1) to make the gills parallel-sided, 

 (2) to cause the pileus to open out more during the process of spore- 

 discharge, (3) to alter the order of ripening and discharge of the 

 spores so that these processes should proceed from below upwards 

 on each gill instead of evenly all over the hymenium, and (4) to 

 introduce the phenomenon of autodigestion of the gills from below 

 upwards so that the spore-free portions of the gills should be 

 systematically removed during the spore-discharge period. One 

 could turn a small Coprinus into a Psathyrella by making an 

 opposite set of changes. I know of no other fungus which could so 

 readily be turned into a typical Coprinus as Psathyrella disseminata. 

 My conclusion in regard to this fungus, therefore, is that, while it 

 is not a Coprinus, it is very closely related to certain species of that 

 genus. Possibly it belongs to a group of Melanosporae from which 

 the Coprini have actually been evolved. 



1 F. Knoll, " Untersuchungen iiber den Bau und die Function der Cystiden und 

 verwandter Organe," Jahrb. fur wiss. BoL, Bd. 50, 1912. Knoll's Coprinus ephemervs 

 appears to be C. curtus. 



