576 RESEARCHES ON FUNGI 



instead of continuing to bridge the spaces during the spore-discharge 

 period, are left as useless pegs projecting from the gill-sides. 



Chapter XI. — In the Micaceus Sub-type : (1) the gills are subparallel- 

 sided and bear large cystidia at their margins ; (2) cystidia are present 

 on the gill-faces and chiefly on those giJl-halves which, before the 

 expansion of the pileus, lie nearest to the stipe ; (3) the cystidia in an 

 unexpanded fruit-body are not attached to an opposing gill by their 

 apices and therefore do not interlock the gills ; (4) before spore-discharge 

 begins, the pileus opens to such an extent that the gills become widely 

 separated from one another, so that the cystidia do not bridge the inter- 

 lamellar spaces but project from the gill-sides like pegs ; (5) the pileus- 

 flesh is grooved and, as the pileus expands, these grooves open out ; and 

 (6) the basidia are tetramorphic. Included in the Micaceus Sub-type 

 is Coprinus micaceus. 



The basidia of Coprinus micaceus, in 1809, were mistaken by Link 

 for asci and Link's illustrations of them served to mislead botanists as 

 to the true nature of basidia for 30 years. 



The author describes the fruit-body of Coprinus micaceus, with special 

 emphasis upon the structure of the gills. 



The basidia of Coprinus micaceus are remarkable in being of four 

 different lengths. This basidial tetramorphism is illustrated by the 

 author in drawings of the hymenium as seen in face view and in cross 

 section. The four sets of basidia represent four basidial generations. 

 There are four sub-zones in the zone of spore-discharge : the longest 

 basidia shed their spores first, the next longest their spores next, and 

 so forth for the remaining two sets of basidia. This order of spore- 

 discharge prevents the shorter basidia from shooting their spores against 

 those of the longer basidia and thus makes for efficiency in the liberation 

 of the spores from the fruit-body as a whole. 



A cystidium usually contains a central clump of protoplasm sus- 

 pended by protoplasmic structures which look like bridles but are in 

 reality the walls of vacuoles. Owing to variations taking place in the 

 size of the vacuoles the clump of protoplasm moves slowly about its 

 central position. 



Successful liberation of the spores in Coprinus micaceus is largely 

 dependent on the weather. In moist weather, the spores are shed and 

 autodigestion proceeds from below upwards on each gill from the bottom 

 to the top of the pileus ; but, in dry weather, the pilei often dry up when 

 the liberation of their spores is only partly accompHshed. 



Chapter XII.— Panus stypticus occurs both in Europe and North 

 America. The divergence of the fruit-bodies, when these are imbri- 

 cating, makes for efficiency in the escape of the spores. The fruit-bodies 

 retain their vitality after desiccation and during frost. 



The mycelium and fruit-bodies of Panus stypticus of North American 

 origin are luminous, while the mycelium and fruit-bodies of Panus stypticus 



