364 Harper.—Sexual Reproduction in Pyronema 
mine with certainty. The only nuclear divisions I have seen 
in the ascogenous hyphae of Pyronema are the simultaneous 
divisions in the hyphal tips just referred to. These divisions 
are very readily observed and can be found in great numbers. 
It would seem if the paired nuclei arise by division of 
a single fusion-nucleus, that the nuclear figures should be 
readily found, but I have been unable to discover them. 
'Pyronema presents in the development of its ascogenous 
hyphae unusually simple conditions. The apothecia are very 
small and the total number of asci produced is not greater 
than could be provided for in the manner described without 
increase in the number of nuclei beyond those which are 
fertilized in the oogonium. In larger forms like Peziza , where 
the apothecia continue to grow in diameter for a long time, 
the conditions may be very different, and nuclear multiplica¬ 
tion in the hyphae may probably provide for the development 
of the successive series of asci formed. It is to be remembered, 
too, that several ascogonia in Pyronema contribute ascogenous 
hyphae to the same apothecium. 
The fate of the sister nuclei to those enclosed in the ascus 
is not certain. Dangeard seems to consider that the apical 
recurved cell of the hypha shows no further growth, though he 
is not very explicit on this point. I have never found evidence 
of this apical cell developing further. I have found frequent 
cases where it had degenerated, and it is safe to assume that 
this is the rule. As to the fate of the fourth nucleus I have 
found a number of preparations which show that in Pyronema , 
at least in some cases, it also does not develop further. 
Fig. 31 shows that the fourth cell from the hyphal tip pro¬ 
duces the second ascus, the third cell containing the nucleus 
in question remaining sterile. The second ascus is formed 
just as the first was, the fourth hyphal cell pushing out into 
a lateral branch whose tip becomes recurved, just as in the 
first case. In the case figured the nuclei in the second branch 
are two in number and are in the equatorial plate stage. If 
the same plan were carried further back it might be the fifth 
cell which would produce the next ascus, the sterile cell in this 
