MUSEUM OF COMPARATIVE ZOOLOGY. 245 
of the clear cells denotes that fecundation has occurred, how have the 
spermatozoa effected an entrance into the egg? The germinative vesicle 
and dot disappear probably before the gonophore is detached from the 
axis of the adult, and, without doubt, before the egg leaves its gono- 
phore. In the immature gonophore in which the body pg. was seen, 
the opening into the bell cavity of the gonophore had not formed. 
Whatever the cell pg. may be, spermatozodn or polar globule, both 
germinative dot and vesicle disappear before the ovum leaves its gono- 
phore. If this event is a result of an impregnation, there seems to 
remain but one conclusion, — namely, that the fertilization of the ovum 
takes place in the gonophore. We are led to suppose that the sperma- 
tozoa either penetrated the sac walls of the ovum and gonophore, or 
passed through the apical canal, which is not in free communication 
with the surface of the ovum. It seems more natural to adopt the latter 
supposition, unless we suppose that nucleus and nucleolus vanish before 
impregnation. The cell, with its enclosed cellular body, which we have 
called the nucleus and nucleolus, disappears and leaves the egg of homo- 
geneous appearance, with the contents made up of the protoplasmic 
network of cells already mentioned. The next change is that by which 
the egg separates itself from the sac in the gonophore in which it is 
contained. 
Several authors have commented upon the peculiar sinuses which are 
sometimes found at this time in the female bell about the egg. These 
sinuses are of many shapes, and lie between the egg and its membranous 
sac (Pl. I. fig. 2). They have the appearance of spaces left here after 
preliminary movements of the ovum before escape from the gonophore, 
or by a shrinkage of the walls. A single gonophore (fig. 4) was observed 
in which the ovum was in the act of escape; and in that gonophore the 
folded remnant of a structure, which may be the sac which formerly 
enclosed the egg, was seen just under the apex of the bell in its cavity. 
The diameter of the opening into the cavity of the bell was in this 
instance observed to be smaller than that of the egg, so that the egg in 
some instances suffers a considerable compression before it escapes from 
the cavity of the gonophore. After the egg leaves the gonophore it 
assumes a spherical form, with a diameter of .45 mm. (PI. I. fig. 6). One 
pole is ruby in color, the other transparent. The network of protoplasm 
which extends through the entire contents imparts to it a cellular ap- 
pearance, while a thin layer, probably of protoplasm, is found over its 
entire surface. 
