624 Bidler .— The Function and Fate of the 
surfaces, C. comatns possesses none in these situations. This marked 
difference between two fairly closely allied species must now be explained. 
In Coprinns comatus cystidia are not required on the general surfaces of the 
gills because the interlamellar spaces are provided for by a structural 
arrangement which renders unicellular props unnecessary. The gill-margins 
in this species are considerably swollen, with the result that they are nearly 
twice as thick as the gill-plates, which alone are covered with the hymenium. 1 
The swollen gill-margins of adjacent gills are in contact with one another 
before the pileus begins to open out. Owing to the presence of these 
marginal thickenings, and also owing to a fitting spacial arrangement of the 
gills where they are attached to the pileus flesh, the gills are kept a sufficient 
distance apart to provide the requisite interlamellar spaces for the free 
development of opposing hymenial layers. In Coprinns atranientarins , on 
the other hand, the gill-margins are no thicker than the other parts of the 
gills (PI. L, Fig. 5). It is clear that the cystidia of C. atr ante ntarius take 
the place of the swellings on the gill-margins of C. comatns . We may 
conclude that in the genus Coprinns there are at least two methods of 
providing for the maintenance of interlamellar spaces: (1) the cystidia 
method, and (2) the gill-margin method. The former is employed not only 
by C. atramentarius but also by C. narcoticns, C. stercorarins , C. niveus , 
C. fimetarius, and a number of other species, and the latter by C. comatns, 
C. sterquilinus , and C. plicatiloidcs . 2 
I have examined the fruit-bodies of the following species of Coprinns : 
C. narcoticns , C. stercorarins , C. nivens, C. lag op ns, C. ephemerns, C. fime- 
tarins , and two other species which occur at Winnipeg, and are either 
identical with or very closely related to C.plicatilis and C. Friesii respectively, 
and have found that the cystidia are removed from the gills of all of them 
at the time of spore-discharge by a process of auto-digestion similar to that 
which occurs in C. atramentarius. It seems very probable that self- 
destruction in connexion with spore-liberation is the rule for cystidia 
wherever they occur in the Coprini. 
In C. stercorarins , C. fimetarius , and C. narcoticns the cystidia have just 
the same functions as in C. atramentarius ; they stretch across the inter¬ 
lamellar spaces from gill to gill, and keep the thin gills separated both during 
spore-development and spore-discharge. In C. niveus the cystidia, which 
are even larger than those of C. atramentarius, stretch across the inter- 
1 A. H. R. Buller, Researches on Fungi, PI. I, Fig. 5 and PI. Ill, Fig. 14. A thin cross- 
section, taken through a pileus of C. comatus just before it opens out, looks like a wheel: the swollen 
marginal gill-bands in close apposition form an inner cylinder around the stipe corresponding to the 
hub, the pileus flesh forms an outer cylinder corresponding to the rim, and the gill-plates held in 
position between the two cylinders correspond to the spokes. 
2 C. plicatiloides, Buller, is apparently a new species. I found it coming up on horse-dung at 
Winnipeg. Vide Researches on Fungi, p. 69. I hope to give a full description of this species in 
another publication. 
