Homothallism and monosporous mycelia in Coprinus. 211 
for fruit-body production and for the development of clamp- 
connections. These three species appear to be entirely lacking 
in clamp-connections, for no clamp-connections were found 
even in their polysporous mycelia. All the septa dividing the 
mycelia into cells were perfectly simple transverse walls (Pl. VI, 
Figs. 13, 14, 15). 
Of Coprinus curtus eight mycelia were isolated, six mono- 
sporous in origin and two polysporous. All the cultures pro- 
duced fruit-bod¥ rudiments. The rudiments in the two poly- 
sporous cultures developed to maturity and the expanded fruit- 
bodies shed spores, but in none of the six monosporous cultures 
did the rudiments develop to the stage of spore-production. 
However, two of the monosporous cultures were sub-cultured 
on dung in large crystallising dishes. Both of them then pro- 
duced numerous perfect fruit-bodies. We can, therefore, state 
that in Coprinus curtus, under favourable conditions, the mono- 
sporous mycelia are able to develop normal fruit-bodies. 
Of Coprinus stellatus only two cultures were made, one mono- 
sporous in origin and the other polysporous, both in dung tubes. 
The polysporous culture produced normal fruit-bodies and the 
monosporous culture only fruit-body rudiments. 
Of Coprinus cordisporus only two cultures were made, one 
monosporous and the other polysporous, both in dung tubes. 
Both cultures produced fruit-body rudiments, but in neither 
culture did any of the rudiments develop into perfect fruit- 
bodies. 
VIII. CoprRiINUS COMATUS. 
The fruit-body of Coprinus comatus Fr., as Buller* has pointed 
out, has a mechanism for the production and liberation of its 
spores practically identical with that of C. sterquilinus; and the 
two species are undoubtedly closely related. It was hoped, 
therefore, that as C. sterquilinus fruits so readily in monosporous 
cultures, this would also happen with.C. comatus. Both mono- 
sporous and polysporous mycelia of C. comatus were therefore 
isolated and transferred to large masses of sterilised horse-dung 
contained in crystallising dishes; but none of them ever fruited. 
A mycelium derived from a stipe was transferred to a large 
mass of sterilised horse-dung contained in a three-litre beaker, 
and covered with three inches of soil. The mycelium was in 
the secondary condition, for its hyphae showed an abundance 
of clamp-connections. It grew well, invaded the whole mass of 
the dung, and penetrated through the soil; but, for some reason 
or other, it failed to fruit. In Coprinus comatus, therefore, the 
non-production of fruit-bodies in the laboratory is common to 
* A. H. R. Buller, loc. cit. pp. 306, 324. 
