28
VICTOR L. LOOSANOFF AND HARRY C. DAVIS
Development of the egg of a bivalve, as described above, is typical
only of a group in which the germinal vesicle breaks upon discharge
F
f 53 x 137
I
206x 184
J
219 x I93
K
233 x 207
L
257x 231
Mactra (Spjsula) solidissima
FIG. 14. Development of Mactra (= S p i ~ u h )
. Y O ~ i r l i 8 m W A from atraight-hinge Htage (A)
Meesurernentq of length arid width of larvae of different
to metwnorphosis (L).
stages are given in microns.
or upon stripping, thus rendering the egg ready for fertilization.
Eggs of Crassostreu virginica and many other species belong to this
category. In the other group stripped eggs continue to retain their