104 FECUNDATION; HETEROGAMETES. 
kinetically, thereby doubling their number, which may be ten times 
greater than the number of egg-cells produced in the oogonium. 
According to Trow the nuclei reveal a structure similar to that in the 
higher plants. Immediately following the division of the nuclei rapid 
changes take place, whose interpretation has led to differences of 
opinion. In both Saprolegnia and Achlya, according to Trow, only 
as many nuclei remain functional in the oogonium as there are egg- 
cells developed, the supernumerary nuclei being digested immediately 
after the karyokinesis mentioned above (Fig. 38, B). In Aeklya 
americana the appearance of the supernumerary nuclei suggests that 
they may possibly divide again before disorganization. In Saprolegnia 
the same author states that some of the degenerating nuclei do really 
appear to unite in pairs. Hartog, on the contrary, maintains that the 
diminished number of nuclei was brought about by nuclear fusions, 
and consequently each functional nucleus remaining in the oogonium 
is the result of such fusions. Judging from what we now know of 
the behavior of nuclei in multinucleated sexual organs in which the 
sexual nuclei are not the product of nuclear fusions, and from the 
evidence which Trow has furnished, I am inclined to believe that the 
evidence is in favor of his conclusions, namely, that the functional 
nuclei of the egg-cells are not the result of fusions. 
As is well known the cytoplasm now begins to ball up in masses 
which eventually form the egg-cells (Fig. 37, B, C). In each mass, 
_as in the completely differentiated egg, only one functional nucleus is 
present. Accompanying or surrounding this nucleus is a conspicuous 
mass of finely granular cytoplasm, which, although appearing less 
highly differentiated than in certain Peronosporee, may havea similar 
function. The young egg rapidly becomes spherical and is provided 
at first with a plasma membrane only. The details in the cytoplasmic 
differentiation of the egg-cells have not, as yet, been critically worked 
out, except in so far as that is possible in the living specimen or from 
observations of the organs zz toto. Whether the balling of the proto- 
plasm described by both earlier and more recent observers is a cleavage 
such as is known to take place in other Phycomycetes can not be 
affirmed positively, but the facts seem to indicate a similar cleavage 
or a closely related process (Fig. 37, B, C).1 
The antheridia, as is also well known, are developed from the ends 
of filaments which apply themselves closely to the surface of the oogo- 
nium (Fig. 37, D). When the cross-wall is formed, separating the 
1 The process of the differentiation of the egg-cells as described in the foregoing paragraph is con- 
firmed by the very careful observations of B. M. Davis on Safrolegnia mixta. The manuscript of 
these pages had left my hands before the receipt of Professor Davis's paper. 
