34 2 Harper.—Sexual Reproduction in Pyronema 
the latter (Fig. 4). The club-shaped antheridium is slightly 
curved over the oogonium, and the conjugating tube grows 
upward on the broad rounded end of the former. The apex 
of the antheridium reaches to or a little past and to one side 
of a line through the long axis of the oogonium and its stalk 
(Figs. I and 14). The conjugating tube lies in this same axis 
at the start, but coming in contact with the antheridium it 
applies itself closely to its surface and thus becomes curved 
and sometimes even hook-shaped to conform to the surface 
of the antheridium. 
It may grow directly up over the apex of the antheridial 
cell and then bend slightly to the right or left at its tip. 
More commonly the antheridium extending beyond the vertex 
of the oogonium, the conjugating tube grows up on one or the 
other of its flanks, and then bends forward and applies its tip 
to the former a little above its vertex. Frequently the end 
of the antheridium bends towards the conjugating tube as if 
to encircle it so that the tube comes to lie partly enclosed 
by the antheridium. Sections in such cases make it appear 
as if the tube cut through the antheridium (PI. XX, Fig. 14). 
Antheridium and tube are growing at the same time, and their 
attraction for each other is apparently mutual. Frequently, 
the antheridium presses against the tube so that a groove 
is formed in its side in which the tube lies. The upper 
margin of this groove may then be developed into a swollen 
lip. All of these conditions and others have been beautifully 
figured by the brothers Tulasne ( 36 ), and I have not thought 
it necessary to reproduce them further ■ than I have done 
in Fig. 1 which is a surface view of a group mounted in 
glycerine. 
The contents of the conjugating tube are at first in direct 
connexion with the oogonium through its base (Fig. 4). It 
is multinucleated at this stage and its nuclei are not different 
from those in the oogonium. Early, however, and long before 
its tip becomes fused with the antheridium, a cross-wall is 
formed at the base of the tube, cutting it off from the 
oogonium. This wall is formed before the sexual cells or 
