Homothallism and monosporous mycelia in Coprinus. 213 
Mile Bensaude found that her Coprinus fimetarius was sterile 
in monosporous cultures and fertile only in cultures containing 
a compound mycelium formed by the anastomosis of her 
mycelium a and her mycelium f, which she presumed as a 
result of her investigations to be of opposite sex. In view of 
Kniep’s discovery that in a heterothallic species even unmated 
haploid mycelia produce fruit-bodies, it is perhaps remarkable 
that Mlle Bensaude’s monosporous cultures did not fruit at all. 
It is desirable that this absence of fruiting powers in mono- 
sporous mycelia should be confirmed by the study of more 
monosporous mycelia than two. It is possible that some mono- 
sporous mycelia of her species could be caused to fruit by 
continuing and extending their cultivation. However, apart 
from the supposed criterion of fertility and sterility, Mlle 
Bensaude has presented us with evidence which seems to prove 
conclusively that her Coprinus fimetarius is heterothallic; for 
she found that clamp-connections and dicaryons were never 
formed in connection with the monosporous mycelia, while 
they were always formed in compound mycelia resulting from 
the mixture of her mycelium «@ and her mycelium f. 
Brefeld* in recording his pioneer work on the life-histories of 
the Basidiomycetes, stated that he obtained fruit-bodies from 
mycelia produced from single spores for the following species: 
Coprinus stercorartus, C. lagopus, C. ephemerus, and C. eph- 
emeroides. Mlle Bensaudej has raised the question as to whether 
or not Brefeld’s mycelia were truly monosporous. The material 
for my investigation has included the first three of Brefeld’s 
species, and for these species my results have been identical 
with his. Thus Mlle Bensaude’s question has been answered in 
Brefeld’s favour. 
Mlle Bensaude, as a matter of theory, considers that the oidia 
produced on the mycelium of her C. fimetarius may be sex- 
carriers, z.e. that a + oidium may unite with a — mycelium 
and thus produce a fertile secondary mycelium bearing clamp- 
connections and fruit-bodies; and vice versa. However, as we 
have seen, both Coprinus lagopus and C. niveus are both homo- 
thallic and yet they produce oidia. It seems clear, therefore, 
that the oidia of these two species cannot be considered to act 
as sex-carriers, at any rate under present-day conditions, for 
the mycelium is homothallic and such sex-carriers, therefore, 
would be superfluous. 
Miss M. L. Badenj stated in 1915 that the spores of Coprinus 
* O. Brefeld, Untersuchungen, Leipzig, Heft 111, 1877. 
t M. Bensaude, Joc. cit. p. 108. 
M. L. Baden, Observations on the Germination of Spores of Coprinus 
sterquilinus Fr., Ann. of Bot., XxIv, 1915, p, 141. 
M.S. 14 
