Rickett.—Fertilization in Sphaerocarpos. 235 
a dense, stringy, deeply staining material filled with various small bodies 
and granules. I have not succeeded in detecting the free-swimming anthero- 
zoid in its passage through these regions, though I have examined many 
slides made from material fixed at various short intervals after flooding. 
Neither have I seen a single case in which I can say with certainty that the 
antherozoid was penetrating the egg. The membrane of the latter is at this 
time very delicate, and, either naturally or as a result of fixation, the surface 
layer of the cytoplasm is somewhat ‘ frayed out ’ into the surrounding space ; 
so that instead of a clear boundary of the egg there is a confusion of little 
strands and granules which seem to belong to the cytoplasmic reticulum. 
Among these bodies the entering antherozoid may in some cases lie con¬ 
cealed. The thinness of the egg membrane at this time has been noted also 
in Riccia sorocarpa by Kny (1866), who thought that the membrane is 
resorbed, at least at the distal end of the egg. 
The first sign of the presence of the antherozoid in the egg is the 
occurrence, in fixations made fifteen, twenty, and forty-five minutes after 
flooding, of a slender curved body lying in the peripheral regions of the egg 
cytoplasm and hardly to be distinguished from the latter. Such a case is 
shown in PI. Ill, Fig. 1 . In several cases these bodies were parallel to the sur¬ 
face of the egg. Some were in the distal end of the egg (Fig. 1 ), some in the 
basal end, and still others in one side. This makes it doubtful whether the 
concavity sometimes seen in the distal end of the egg, described above, has 
any real relation to the entrance of the antherozoid. If it really represents 
the receptive spot described for other forms, then the receptive spot, in 
Sphaerocarpos at least, is not the only place at which antherozoids can 
penetrate the egg. It is noteworthy that these bodies which I have inter¬ 
preted as antherozoids correspond in their variable position in the egg 
cytoplasm to the male nuclei clearly seen in later stages, which similarly may 
approach the female nucleus from above, from below, and from the side. In 
one case, a slender strand of the mucilaginous material that fills the venter 
extended across the ventral cavity from the archegonial wall to a point 
on the surface of the egg near where the antherozoid lay inside the egg. 
First Phase. 
The antherozoid first appears clearly and unmistakably discernible as 
a small, rod-shaped, often curved body lying in the egg cytoplasm, sur¬ 
rounded by a clear space of varying dimensions, whose boundaries are not 
clearly defined. This body is dense, staining most readily with safranin, 
and apparently homogeneous ; I have found no evidence of a differentiation 
of its contents at this stage. It may be pointed at one or both ends, but 
usually both ends are rounded. It measures about 6 by 1 * 5 /x. This stage 
is illustrated in Fig. 2 . 
Whether this is the whole antherozoid or only its nucleus could not be 
