61 7 
Cystidia of Coprinus atramentarius. 
so far as my observation has gone, is most frequently found on partly 
buried stumps and logs of wood. In England I have often noticed the 
fruit-bodies at the foot of gate-posts and the supports of fence-rails. 
Probably the mycelium is specialized for the destruction of wood. 
The fruit-bodies of Coprinus atramentarius are usually clustered, four 
or more individuals often being united by the bases of their stipes. The 
pilei are silvery grey, ashen grey, or sometimes brownish in colour. 1 They 
are usually more or less scaly, frequently plicate or lobed, and at first egg- 
shaped, although later on during auto-digestion they become expanded 
(PL L, Figs. 1-4). The gills are exceedingly thin, and at the same time 
very broad ; they are somewhat less than 0-2 mm. thick and often 10 or 
12 mm. wide. On account of their thinness and breadth they are mechani¬ 
cally remarkably weak, and in this respect differ much from the gills of the 
Mushroom and of fruit-bodies of the same type. When two gills are torn 
apart, the cystidia can be seen with the naked eye as pellucid processes pro¬ 
jecting in large numbers from the hymenial surfaces. 
If a median cross-section be taken through the gills (i. e. in the direction 
c-d in PL L, Fig. 1), the cystidia can readily be made out, extending across 
the interlamellar spaces. They present the appearance shown in PL L, 
Fig. 5. A thin cross-section more highly magnified (PL L, Fig. 8) shows 
that each cystidium consists of a single large cylindrical cell which has 
a narrowed end inserted in the hymenium from which it has originated, 
and a rounded apex which has come to be partly embedded in the hymenium 
of the opposing gill. The connexion of the cystidia with more or less 
cylindrical subhymenial cells can often be made out (cf. PL L, Figs. 8, 9, 10, 
and 11). There can be no doubt that the apical end of each cystidium 
becomes fixed into the hymenium against which it has come to press. This 
is proved by the fact that when the gills are mature, one cannot pull any 
adjacent two apart without tearing them. The cystidia hold the gills 
tightly bound together. When one succeeds in forcibly separating parts of 
two neighbouring gills, one finds that although the cystidia have mostly 
separated from one of the gills at their apical ends, and have thus remained 
attached to the other gill by their basal ends (PL LI, Fig. 19, i), not infre¬ 
quently the reverse happens ; the cystidia which have broken away at their 
basal ends and have remained attached at their apical ends then have the 
appearance shown in PL LI, Fig. 19 ,j. Worthington Smith 2 doubtless saw 
cystidia projecting in this manner, for his figure shows one upside down. 
He evidently thought that the narrowed end of each cystidium was the 
apical end, and that it projected freely into the interlamellar space. It may 
well have been this error which suggested to him that a cystidium is really 
1 Cf. G. F. Atkinson, Studies of American Fungi. Ithaca, 1901, p. 40. Some excellent photo¬ 
graphs of Coprinus atramentarius are given in his Figs. 39-42. 
2 W. Smith, Cystidia in the Mushroom Tribe. Grevillea, vol. x, 1881, p. 78. 
