THE CYSTIDIA OF COPRINUS COMATUS. 
29 
appeared in the Annals of Botany, there can be little doubt. This 
function, like the last, is also to facilitate spore distribution, but in 
a different manner. The gills of Coprinus are very thin and film- 
like, and it is certain that without the cystidia they would in all 
probability become stuck together by moisture and other external 
causes in such a way that spore distribution would become im- 
possible. The cystidia grow out from the surface of one gill and 
become embedded in the tissue of the opposite one. They are 
sufficiently numerous to keep the gills apart, and to add to the 
firmness of the structure by binding them all firmly together. 
In the species figured by Buller ( Coprinus atramentarius J, each 
cystidium consists of a large cylindrical cell, one end of which 
is narrow and inserted in the hymenium, from which it grows out ; 
the other end is rounded off and becomes embedded in the tissue 
of the opposite gill, where it appears to become fixed. 
In the species which I sectioned (Fig. I. -II.) ( Coprinus comatus y 
Fr.), instead of stretching from one gill to the other, like those 
figured by Buller, two cystidia, arising from opposite gills, fuse 
together where they meet between the surfaces of either gill, and 
in this way bridge over the space between the gills and thus serve 
the same purpose as those in Coprinus atrameiitarius already 
described. In some cases the two fusing cystidia are opposite each 
other, in others they are slightly displaced, and in the latter case 
one cystidium often bends round from its original position in order 
to fuse. (Fig. II.). 
The complete way in which these cystidia fuse is shown by the 
fact that it is impossible to separate the gills without breaking the 
tissue, and in nearly every case when an attempt has been made to 
separate them, the cystidia have remained fused and the gills 
have split in half, still attached by their surfaces. (Fig. I.). 
In other cases when an attempt has been made to separate them, 
the Cystidia have broken away from the gill in which they 
originated (Fig. III.) and have a flask-like form, due to the fact that 
they often draw T out with them part of the narrow hypha from 
which they have arisen. This hypha is, of course, open at the end, 
with the contents exuding to a greater or less extent from the 
opening, and it is probable that this is what was observed — though 
in a species in which the cystidia were embedded in the tissue of 
the opposite gill — by the writer who pictures them as the flask- 
shaped cell with lids. 
The above description is based on observations of young fructifi- 
cations. Fig. IV. is drawn from a section of mature material. 
The cystidia are in this case essentially the same as in the previous 
one, the chief differences seem to be that they are fewer in number, 
some evidently having degenerated ; they are also much larger ; 
the gills in this way have become still more separated ; the 
cystidia have also become transparent. Many may still be seen 
torn away from the tissue of the gill and remaining attached to the 
fused cystidia of the opposite gill. 
