File:The American lobster (Cut 27-30) (6678738929).jpg

Bull II S F. C. 1895. The American Lobster. (To face page 208 )
Plate H.
Cut 27. — Surface view of embryo, show-
ing buds of first pair of antenna? and
clouds of in-wandering cells. Tbe lat-
ter extend in great cumulus-like folds
and surround large masses of yolk with
tbin layers of cells. Embryo about 9
days old. August 6, 1891. 29 diameters.
In cuts 25-33 tbe eggs were fixed with
hot water and Mayer's picro-sulpburic
acid, and stained in Kleinenberg's hsemo-
loxylon or Grenadier's borax-carmine.
Cut 28. — Surface view of embryo, show-
ing buds of first pair of antennas and
of mandibles. Tbe stomodaeum is
present in form of a small transverse
pit, on tbe level of a line drawn
through tbe posterior margins of the
antennary buds. Tbe outlines of the
masses of yolk-cells appear much
more circumscribed than in the earlier
stage shown in cut 27. Embryo 9 to
10 days old. August 5, 1891. 29 dia-
meters.
Cut 29. — Surface view of early egg-
nauplius embryo, showing buds of
the first and second antenna? and
the mandibles. Mouth or opening
of stomodaeum distinct; in-wandering
cells beneath the thoracic abdominal
plate shaded dark. The yolk-cells are
still further circumscribed to outward
appearance, having wandered far into
the egg. Optic disks more clearly de-
fined. Embryo about 10 days old. 29
diameters.
Cut 30. — Surface view of egg nauplius,
slightly older than that shown in cut 29;
second antenna? bifid; labrum and tho-
racic abdominal fold present; embryo
about 11 days old. July 12. 29 diame-
ters.
In cuts 25-30 surface-cells are roughly
indicated only in the immediate region
of the embryo.