Fig. 1. Section through the germinal disc of a ripe ovarian ovum of the
Skate. _gv._ germinal vesicle.
Fig. 2. Surface-view of a germinal disc with two furrows.
Figs. 3, 4, 5. Surface-views of three germinal discs in different stages of
segmentation.
Fig. 6. Section through the germinal disc represented in fig 3. _n._
nucleus; _x._ edge of germinal disc. The engraver has not accurately copied
my original drawings in respect to the structure of the segmentation
furrows.
Figs. 6_a_ and 6_b_. Two furrows of the same germinal disc more highly
magnified.
Fig. 6_c_. A nucleus from the same germinal disc highly magnified.
Fig. 7. Section through a germinal disc of the same age as that represented
in fig. 4. _n._ nucleus; _nx._ modified nucleus; _nx´._ modified nucleus of
the yolk; _f._ furrow appearing in the yolk around the germinal disc.
Figs. 7_a_, 7_b_, 7_c_. Three segments with modified nuclei from the same
germinal disc.
Fig. 8. Section through a somewhat older germinal disc. _ep._ epiblast;
_n´._ nuclei of yolk.
Figs. 8_a_, 8_b_, 8_c_. Modified nuclei from the yolk from the same
germinal disc.
Fig. 8_d_. Segment in the act of division from the same germinal disc.
Fig. 9. Section through a germinal disc in which the segmentation is
completed. It shews the larger collection of cells at the embryonic end of
the germinal disc than at the non-embryonic. _ep._ epiblast.