202 Transactions British Mycological Society. 
II. METHODS. 
Horse-dung balls were collected from stables and from the 
streets of Winnipeg and were placed in a large glass chamber 
set on a table in the laboratory. In the course of a few weeks, 
fruit-bodies of the nine species of Coprinus named above, with 
the exception of Coprinus comatus, appeared on the dung balls. 
Spore-deposits were collected on sterilised filter paper by placing 
this beneath pilei which were shedding spores. When a spore- 
deposit had been obtained, the filter paper bearing it was 
labelled and set in a sterilised glass container. It was then ready 
for use at any time. 
Experiments were made with beef-peptone agar, beef-peptone 
gelatine, malt gelatine, and potato agar; but the medium used 
for all the later experiments was a horse-dung decoction 
solidified with 1-3-2 per cent. agar. This culture medium was 
made as follows. Approximately 400 grams of fresh horse-dung, 
were put in a beaker with 1000 cc. of tap-water and the whole 
was placed in a steam steriliser at a temperature of 100° C. for 
30 minutes. To the decoction so obtained was then added 1-3+2 
per cent. of melted agar. The horse-dung agar was then filtered 
through cotton-wool, and, thereafter, 10 cc. of it was poured 
into each of a series of test-tubes. These tubes, which were 
plugged with cotton-wool, were then autoclaved at a pressure 
of seven pounds for half an hour or longer. The medium was 
not titrated. 
To isolate the monosporous mycelia, the poured plate or 
Petri dish method was employed. Tubes of horse-dung agar 
which had been melted and cooled to a temperature of 42°— 
45° C., were inoculated with a few spores introduced by means 
of a sterilised platinum needle from a spore-deposit. The agar 
was then poured into sterilised Petri dishes. The dishes were 
placed in a cupboard and kept at room temperature, 7.e. at 
about 20°-22° C. After from two to five days, varying with the 
species, minute mycelial masses could be seen with the naked 
eye upon the agar; and, with the low power of the microscope, 
it was found that some of these had developed from small 
clumps of spores and others from single spores (Pl. VI, Figs. 1, 
2, 5, 10). The spores could be very readily distinguished owing 
to their blackness. When a mycelium was found to have de- 
veloped from a single spore which was far distant from any 
other spore or mycelium, it was removed from the Petri dish. 
with a sterilised platinum needle and transferred to a dung-agar 
slant. Usually within two to four days the mycelium had 
extended itself considerably over the agar surface. It was then 
finally transferred, along with the agar which it covered, to a 
