Homothallism and monosporous mycelia in Coprinus, 203 
wide glass tube (length 4 inches, breadth 1-25 inches) which, 
after having been half filled with fresh horse-dung and plugged 
with cotton-wool, had been sterilised in flowing steam for 45 
minutes on three successive days. This tube was set in a cup- 
board or on a table away from direct sunlight and kept at room 
temperature. 
Whilst isolating monosporous mycelia of any species, a poly- 
sporous mycelium which had originated from several germinating 
spores of a spore clump, was also isolated; and it was transferred 
first to a slant and then to a wide tube in the same manner as, 
and at the same time as, the monosporous mycelia. Thus controls 
were provided. 
III. CopriNnus STEROQUILINUS. 
The first experiments were made with Coprinus sterquilinus, 
a species which has very large black spores, a rapidly-growing 
dense white mycelium, and a large fruit-body*. Potato agar was 
employed for the plates and slants in the earlier cultures, and 
dung agar in the later ones. The methods of cultivation were 
identical with those described above except in the last few 
cultures where I transferred the monosporous mycelia directly 
from the Petri dish to the tubes of sterilised dung. Altogether 
twenty-five monosporous mycelia were isolated, but four of 
them failed to grow after being transferred. Each of the twenty- 
one mycelia which survived transference, grew well and com- 
pletely covered the horse-dung balls with a white felt-work. 
A considerable number of rudimentary fruit-bodies soon ap- 
peared on the mycelium covering the dung balls; and, after 
24-31 days from the time the spores were first sown, some of 
the fruit-bodies elongated their stipes, expanded their pilei, and 
shed great numbers of spores. Thus each of the twenty-one 
monosporous mycelia fruited in a perfectly normal manner. 
Included in the twenty-one monosporous cultures was a series 
which may be described as follows. A wild fruit-body came up 
on horse-dung taken from a stable, and it shed spores which 
were collected as a spore-deposit. Some of the spores were 
plated out on agar and thus a monosporous mycelium was 
obtained. A month after being transferred to sterilised horse- 
dung in the usual way, the mycelium fruited. From this second 
fruit-body, a second monosporous mycelium was obtained which 
at the end of a second month also fruited; and from the third 
fruit-body a third monosporous mycelium was obtained which 
* For a description of the fruit-body with illustrations vide A. H. R. Buller, 
Die Erzeugung und Befreiung der Sporen bei Coprinus sterquilinus, Pfeffer’s 
Festschrift, identical with Jahrb. f. wiss. Bot. LvI, 1915, pp. 299-329, Taf. 11 
and 111. 
