ACHLYA AND SAPROLEGNIA, 105 
antheridium from the filament it contains a small but variable number 
of nuclei. These nuclei undergo: the same changes as those in the 
oogonium, Zz. e., they divide karyokinetically, and some disorganize. 
The fecundation-tubes are now developed and usually more than one 
from each antheridium. They penetrate the wall of the oogonium at 
Fig. 37,—Stages in development of sexual organs of A. ameri- 
cana var. cimbrica,—(After Trow.) 
A, young odgonium before delimination from hypha; base 
of globular enlargement incloses a vacuole which is con- 
tinued back into hypha. 
B; much later stage; an antheridium applied to odégonium, 
both organs delimited from hyphz; protoplasm of oégo- 
nium, which now forms a thick wall-layer, has begun to 
ball up to form the eggs. 
C, still later stage ; balling more pronounced, 
D, odgonium with differentiated eggs; conjugation-tubes from 
applied antheridium have entered odgonium and become 
applied to some of the eggs. 
A-D drawn from living material. 
the thinner places or pits, and grow in among the eggs (Fig. 37, D, f. t.). 
These tubes contain nuclei which are exactly like those of the eggs, 
though smaller. In one case Trow was able, as he states (99, p. 159) 
to trace the fecundation-tube without a break into an egg which was 
already surrounded by a delicate membrane (Fig. 38, C). This 
instance ‘¢suggests that the fertilization-tube grows up to the egg, 
presses against it, indents it, stimulates it to the formation of a cell-wall, 
and grows obliquely into the mass of protoplasm, carrying at its apex 
a single nucleus (Fig. 38, C). . . . Later stages tend to show 
that the wall of the tube within the oosphere breaks down, the nucleus, 
