340 Harper.—Sexual Reproduction in Pyronema 
reaching such a point would, by its vigorous branching, pro¬ 
duce a centre of growth and result in a radially arranged 
mycelium such as I have described. The Fungus certainly 
spreads by means of loose, cobwebby hyphae over consider¬ 
ably greater areas than are ultimately covered by the 
apothecia. These scattered hyphae are hardly to be described 
as definite stolons such as are found in Rhizopus , and yet 
their general function is much the same. 
I have never found any traces of asexual reproduction by 
conidia or otherwise. Sexual reproduction is so prolific 
apparently, and the ascus-fruits are produced in so short 
a time, that asexual reproduction has been dispensed with. 
I have not tried germinating the spores in nutrient media, and 
it is quite possible if they could be made to grow in this way 
that some type of vegetation fragmentation might appear, 
but it is quite certain that such reproduction does not occur, 
or at least does not play any prominent role in the life 
history of the Fungus in nature. Pyronema has developed 
the opposite habit to that found in Penicillium , for example, 
where the asexual conidia are the predominant reproductive 
bodies, ascocarps being formed rarely or perhaps never in 
nature. What has led to such different lines of development 
in the two forms is as yet an unsolved problem. Doubtless 
the explanation of the predominance of the Penicillium and 
the comparative rarity of Pyrone 7 na is involved to some 
degree at least in this difference in their reproductive habit. 
Vertical median sections through a mycelial growth such 
as I have described show ascocarps in various stages of 
development, the older near the centre, the younger toward 
the periphery. The first indication of sexual reproduction, 
as it has so many times been described, consists in the forma¬ 
tion of thickened hyphal branches which tend to stand vertical 
to the substratum. Thin microtome sections are not favour¬ 
able for the investigation of the question as to whether these 
knots of hyphae arise from one or more than one parent 
branch. The results of a study of the question on living 
material by the different authors have been already referred 
