114 ASCOMYCETES AND RHODOPHYCE, 
42, D). During this process, or sometimes later, as stated in a pre- 
ceding paragraph, the nuclei of the trichogyne disintegrate. When 
this has taken place the antheridial nuclei begin to migrate through the 
pore into the trichogyne, whose protoplasmic contents become still 
further disorganized. This migration of nuclei continues until the 
tube is quite densely filled and sometimes slightly swollen (Fig. 42, E). 
In the meantime conspicuous changes have been taking place in the 
oogonium. The nuclei, which are evenly distributed throughout the 
interior of this organ, begin to migrate toward the center, where they 
* 
Fig. 42.—Copulation of sexual organs of Pyronema —(After Harper.) 
D, the trichogyne has copulated with antheridium, nuclei in trichogyne disintegrated ; hypothecial 
hyphe springing from stalk cells. 
E, trichogyne filled with nuclei from antheridium ; antheridium curved around trichogyne so that the 
TT appears in section to cut through it; trichogyne still separated from oégonium by transverse 
become collected into a dense, hollow sphere, equal in diameter to 
about half that of the odgonium, or they may aggregate into an irreg- 
ular, crescent-shaped mass in either the upper or lower half of the 
oogonium (Fig. 42, E).. Less frequently several masses of nuclei are 
formed instead of one. 
The cytoplasm of the oégonium, which was charged with densely 
staining substances, becomes tenuous and loosely spongy in texture. 
After the oogonial nuclei have aggregated in the center of the egg-cell, 
the basal wall of the trichogyne breaks down and the antheridial nuclei 
