THE CYSTIDIA OF COPRINUS COMATUS. 
F. De la Mare Norris. 
COPRINUS, the ink fungus, like most of the Agaricineae, has 
its spore-bearing layer or hymenium on the under surface of 
an umbrella-like structure, the pileus, which is raised above the 
ground on a long stipe. This hymenium covers the surface of 
a number of gills radiating from the stipe to the margin of 
the pileus, the adjacent gills lying very close to one another. 
The spores borne upon the gills ripen progressively from the lower 
margin upwards and, as they are set free, the tissue of the gill 
gradually deliquesces. The cystidia are special large cells present 
amongst the spore-bearing cells or basidia (see Fig. II.) in the 
hymenium, but themselves bearing no spores. As to the function 
these cystidia perform various theories have been advanced. At 
one time they were regarded by some as male organs, and one 
writer, Worthington Smith 1 , went so far as to state that they were 
antheridia, which produced spermatozoa. He was of the opinion 
they fell to the ground and that the liberated spermatozoa found 
their way to the spores, and by fusing with them brought about 
fertilization. 
One writer figured them as flasked-shaped bodies, the mouths of 
which were closed by lids, and he thought that the contents of each 
cystidium escaped by the breaking off of the lid. He does not 
state whether he ever actually observed the lids, and it is quite 
easy to account for the flask-shaped cystidia, with the cell contents 
issuing from their necks, in quite another way, to which I will 
refer later after dealing with the true function and structure of 
the cystidia. 
It is thought by many that the cystidia exude a digestive enzyme 
which acts on the tissue and causes it to decompose. This is what 
causes the fungus, as it grows older, to disorganise into a slimy, 
black, inky mass, from which fact the fungi derive their common 
name of "Ink-Fungi." The spores ripen in definite zones, be- 
ginning at the base of each gill and progressing upwards to the 
top, and it is thought that by the falling oft 0 of the older and useless 
parts of the gills that the ripe spores have an easier access to 
the outside. Each zone of cystidia has entirely vanished before the 
zone of spores above it is ripe so that there is no fear of the spores 
adhering to the sticky decomposing mass. Whether it is only 
the cystidia that exude this digesting enzyme, or whether the 
paraphyses and old basidia share in the work, we do not know. 
But the cystidia have another important function, a function of 
which, after the work of A. H. R. Buller 2 , which has recently 
1 W. Smith, Grevillea. Vol. IV., 1875-76, p. 30. 
2 A. H. R. Buller. Annals of Botany, XXIV. 
