354 Fraser. — On the Sexuality and Development of 
12, 13, &c.), and its nuclei are intermediate in appearance between those of 
the ascogonium and of the ordinary gametophytic cells (Fig. 14). Such 
facts are suggestive of some special activity, and it is possibly significant, in 
this connexion, that the cell next below the ascogonium in Pyronema con- 
flnens , where the antheridium develops independently, differs in no way 
from the other supporting cells of the archicarp. 
The antheridium contains a number of nuclei, but these either remain 
in situ (Fig. 13) or pass into the terminal cell of the trichogyne (Fig. 12), 
and they may be observed, often degenerating, but sometimes in an 
apparently healthy state, late in the development of the ascocarp. This is 
the case in the specimen shown in Fig. 18, where the ascogonium is already 
almost empty. The limits of the antheridium and terminal cell of the 
trichogyne are here difficult to determine. 
Often no clear indication of an antheridium could be found, and it 
would seem that, in some cases, an antheridium is not developed ; but it is 
impossible to speak with certainty of an organ which is distinguished 
mainly by its shape and position, and which can be studied only in section. 
Fertilization . In the specimen represented in Fig. 10 the ascogonium 
is already giving off ascogenous hyphae, while the trichogyne is still 
exposed at the exterior of the sheath and no trace of an antheridium can 
be made out. Again, Fig. 13 shows a branching ascogonium, and a well- 
defined antheridium, in which, however, numerous nuclei may, at this late 
stage, be observed ; and in Figs. 12 and 18, although many male nuclei 
appear to have passed into the terminal cell of the trichogyne, they are cut 
off by its lower cells from the ascogonium. 
Such cases are of frequent occurrence, and it would seem, therefore, 
that ordinary fertilization of the ascogonial by the antheridial nuclei does 
not normally occur. It is of course possible that this process may still 
occasionally take place, but among the nearly 300 ascogonia examined no 
satisfactory evidence of such a fertilization was found. 
Another process, however, was frequently observed ; the ascogonial, 
or female nuclei, were seen to fuse in pairs (Figs. 15, 16, 17) in a manner 
similar to that observed in Humaria grannlata. The nuclei first fuse 
(Fig. 15), and the fusion of the nucleoli takes place later (Fig. 16). 
The fusions occur at very various stages in the development of the 
ascocarp; the earliest seen (Fig. 17) was in the ascogonium shown in 
Fig. 9. In this case it is scarcely possible that antheridial nuclei have 
entered the ascogonium, and that the nuclei in process of fusion are male 
and female, for the trichogyne can be traced with great distinctness, and is 
entirely free either from antheridial or from sheath cells. 
Fusions may also be observed when the ascogonium is nearly empty, 
but the majority probably take place at about the stage represented in 
Figs. 12 or 13, and they occur in various parts of the ascogonium. 
