292 RESEARCHES ON FUNGI 



interlamellar spaces and by suitable relations between the distance 

 to which the spores are shot away from their basidia and the 

 distance of the discharging basidia from the extreme edges of the 

 autodigesting gills. 



Summary concerning the Structure and Function of the Cystidia. 

 — From the facts which have now been recorded it seems clear that 

 the cystidia of Coprinus atramentarius are fitted for their distance- 

 piece function by their shape, size, contents, position, mode of 

 attachment at each end, number, and early development ; whilst 

 the time, order, and mode of their destruction are arrangements 

 which prevent their becoming obstacles to the escape of the spores 

 from the fruit-body. Even if we were to search throughout the 

 whole range of the vegetable kingdom it would be difficult to find any 

 more beautiful and perfect example of cellular specialisation and of 

 adaptation of structure to function than is here afforded us. 



The Pilei of Coprinus atramentarius and C. comatus compared. — 

 The replacement of the flange arrangement for separating the gills 

 by the cystidial permits of a greater compactness of the gills in the 

 fruit-body. Every one who has examined an expanding fruit-body 

 of Coprinus atramentarius must have been struck by the thinness 

 and closeness of the gills and by the unusual solidarity of the mass 

 which they make up. On the other hand, an expanding fruit-body 

 of Coprinus comatus or C. sterquilinus is not nearly so compact, as 

 far as the gills are concerned. If one takes two fruit-bodies of 

 equal diameter, one of C. atramentarius and the other of C. comatus, 

 one finds by counting that there are about twice as many gills in 

 the former as in the latter. This is due to the fact that the gills 

 are thinner and the interlamellar spaces are narrower in C. atra- 

 mentarius than they are in C. comatus. The cystidial arrangement 

 for separating the gills, as developed in Coprinus atramentarius, 

 evidently permits of a maximum number of gills being packed into 

 the pileus. It also permits of the gills (which the cystidia support) 

 being extremely thin and, at the same time, extremely broad. 

 However, in Coprinus comatus, the flange arrangement of separating 

 the gills, while involving the presence of fewer and narrower gills 

 than the cystidial arrangement as exemplified in C. atramentarius, 

 appears to allow of a partially compensating advantage, namely, 



