274 Shaw . — The Fertilization of Onoclea. 
terior turn of the corkscrew. The spermatozoid of O. sensibilis 
is like that of Chara , as described by Belajeff 1 , in having the 
cytoplasm extending along the nucleus. The thickened 
outer edge of the cytoplasmic band may correspond to 
the ‘ Riickfaden ’ which Belajeff was able to distinguish in the 
forward cytoplasm of the spermatozoid of Chara until a late 
stage in its development. 
Long before the archegonium opens the egg-nucleus comes 
to the resting condition, and contains one or more nucleoli. 
The ventral canal-cell is the smallest cell in the archegonium. 
After it is formed, the pressure of the egg makes it still 
smaller and concave, and its nucleus becomes flattened. In 
later stages the walls of the ventral canal-cell swell up, and 
by pressure cause the egg to become concave on the outer 
side, which later forms the receptive spot. In these stages 
the egg-nucleus also is flattened and concave. The egg is in 
this condition when the archegonium opens. In the living 
sections, under the microscope, the writer observed the egg 
to swell as soon as the canal was cleared of its dissolving 
contents, and fill up the venter. If many spermatozoids were 
near, they swarmed into the canal, and a large number made 
their way into the venter, where they swarmed about freely, 
quite differently from those in the close quarters of the neck, 
which were motionless or moved slowly. Often spermatozoids 
which had entered the venter found the canal again, and 
made their way out, slowly through the narrower portion of 
the canal, but rapidly in the wider part. On first entering 
the slime discharged by the archegonium, the spermatozoids 
left their trophoplasmic vesicles behind, and their motion was 
retarded. It was the resistance of the slime which pulled 
off the vesicles. In the canal the slimy mucilage seemed to 
be denser, and when a spermatozoid entered it, the corkscrew 
spiral became drawn out, and the number of turns increased, 
and the forward motion of the spermatozoid was accompanied 
by a rotation which corresponded to the pitch of the screw. 
1 Belajeff ’94, p. 43. 
