33 ^ Harper.—Sexual Reproduction in Pyronema 
a spermogonium in Collema is due to the development of 
dioecism in the latter. 
Kihlmann concludes, however, that the actual fertilization 
of Pyronema is still an hypothesis. The homology of the 
reproductive organs is unquestioned, but the possibility that 
they are not functional still remains, since parthenogenesis 
and apogamy are widely distributed phenomena. The nature 
of the sexual process was much better understood when 
Kihlmann published his work in 1885, than it was when 
Tulasne and De Bary did their work. Still in spite of the 
progress that had been made, Kihlmann remarks that he 
considers it a question whether nuclei are present in the sexual 
cells of Pyronema , and further, whether their behaviour, if 
present, would show phenomena of decisive worth for settling 
the question of fertilization. 
Observations on Pyronema, 
The sexual reproductive apparatus in Pyronema is the 
largest and most conspicuous which has yet been discovered 
among the Ascomycetes. In it we have a case analogous 
to that of Sporodinia among the Zygomycetes, in which the 
zygospores, contrary to the habit of the group, are produced 
on an aerial mycelium instead of beneath the surface of the 
substratum. The young ascus-fruits of Pyronema are visible 
with a good magnifier, and their distribution and approximate 
stage of development can thus be determined with con¬ 
siderable certainty. 
I found the form used, which seems to be P. conjluens , 
abundant in woods on burned places, especially in half-charred 
masses of 4 eaves, though it also occurs among damp well- 
decayed leaves where there has been no fire. When con¬ 
ditions are favourable it is extremely common, and can be 
obtained in unlimited quantities in all stages of growth. The 
development of the mature fruits from the time of the appear¬ 
ance of the sexual apparatus only requires a few days. The 
development of the sexual apparatus itself up to the stage 
when fertilization occurs requires not more than twenty-four 
