PSATHYRA URTICAECOLA 135 



in a clamja chamber. The fruit-bodies underwent autodigestion 

 during the following night. .Several other crops of fruit-bodies 

 subsequently came up, and each of them shed its spores and became 

 reduced by autodigestion during the night (Fig. 55, cf. A and B). 

 On examining the fruit-bodies with the microscope, I found that 

 all the seven criteria already given for the genus Coprinus were 

 satisfied. The gills of the pileus are (1) exceedingly thin, for they 

 scarcely exceed O'l mm. in thickness, (2) parallel-sided, and (3) non- 

 geotropic, for they are held together in a solid mass in the same 

 way as in Coprinus atramentarius. Since the gills are parallel- 

 sided, non-geotropic, and closely packed, it must of necessity 

 happen that (4) one side of a gill looks slightly upwards and the 

 other slightly downwards. The spores were observed (5) to ripen 

 and (6) to be discharged from below upwards on each gill ; and, 

 finally, (7) typical coprinoid autodigestion was seen to take place : 

 the gills were gradually destroyed from below upwards, the spore- 

 free portion being liquefied and thus gradually removed out of the 

 way of the falling spores. 



As we have seen, Berkeley remarked on the Kew herbarium 

 sheet that Psathyra urticaecola has " the habit of a Coprinus." 

 The reason why Berkeley and Broome failed to discover that this 

 fungus is a Coprinus and not a Psathyra is probably because the 

 autodigestion of the gills takes place at night. I found that the 

 gills are white in the morning but turn chocolate from below upwards 

 with the ripening of the spores during the afternoon (Fig. 54), and 

 that spore-discharge takes place in the evening and night. By 

 the following morning the fruit-bodies are exhausted and falling 

 (Fig. 55, cf. A and B). 



The spores, like those of several other very small species of 

 Coprinus, are not jet-black but distinctly chocolate-coloured. 

 They measure 7 x 4 /x and are oval. The top of the pileus is 

 chalky white and beset with flocculent masses of matted hyphae. 

 The cystidia are cylindric-oval and are firmly fixed by both ends 

 into opposing gills which they bridge as in Coprinus atramentarius. 

 The basidia are dimorphic, as is usual for Coprini ; but the long 

 and short basidia are rather freely spaced. The paraphyses are 

 distinctly pedicellate. 



