Cystidia of Coprinus atramentarius. 625 
lamellar spaces during the early stages of the development of the pileus, and 
at this time serve to keep the gills apart. However, during the expansion of 
the pileus just before spore-discharge begins, the gills become widely 
separated, with a consequent increase in the width of the interlamellar 
spaces. As a result of this the cystidia become too short to stretch across 
the interlamellar spaces any longer, and when spore-discharge begins, they 
simply project from the gills from which they have originated, so that their 
free ends come to be situated at some distance from the opposing gills. It 
thus appears that in Coprinus niveus the cystidia cease to have any function, 
and become useless as soon as the pileus begins to open out. In some 
species, e. g. C. lagopus , most of the cystidia are not long enough to stretch 
right across the interlamellar spaces. However, they probably serve as 
guards, so that if by accident during development one gill should approach 
too near another, the general hymenial surfaces of opposing gills will not 
come into contact. It is possible that in some species some or all of the 
cystidia may have become vestigial. A more detailed account of the 
genus Coprimes I shall reserve for a future publication. 
Massee 1 has stated that ‘ many species included in Coprinus , as C. pli- 
catilis and others having dry non-deliquescent gills, have no real affinity 
with this genus ’. Whilst dissenting from Massee’s view that C. plicatilis 
and its allies should be removed from the genus Coprinus, I 2 accepted his 
implied statement that these species had gills which were non-deliquescent; 
and I 3 further said that there is no auto-digestion in C. plicatiloides . My 
recent studies have taught me that both Massee and I have been mistaken 
in supposing that there is no auto-digestion in the small ephemeral species 
which expand like parasols. I have found that there is a certain amount of 
auto-digestion at the gill-edges of C. plicatiloides, C. plicatilisp and C. ephe¬ 
meras, which takes place in connexion with spore-liberation in the same 
general way as in C. comatus. In these species the gills split from above 
downwards, each one becoming Y" s ^ a P e< ^ in cross-section. The auto¬ 
digestion which takes place is limited to the lower portion of the unsplit part 
of each gill. It does not begin until the time when spores are about to be 
liberated, and is so slight that it is not surprising that it has hitherto been 
overlooked. I have now examined the following species of Coprinus : 
C. comatus , C. atramentarius, C. sterquilinus, C. fimetarius, C. micaceus, 
C. narcoticus, C. stercorarius, C. niveus, C. lagopus, C. plicatilis, C. plicati¬ 
loides, C. ephemeras , and C. Friesii, and have found that auto-digestion 
to a greater or less extent takes place in all of them. These thirteen 
species are fairly representative of their genus, and until some species 
1 G. Massee, Textbook of Fungi, London, 1906, p. 364. 
2 A. Ii. R. Buller, Researches on Fungi, London, p. 209. 
3 Ibid., p. 75. 
3 Auto-digestion of the cystidia and gill-margins certainly takes place in the form of C. plicatilis 
found at Winnipeg, but possibly this is not true of the somewhat dry English form. 
