BIVALVE MOLLUSCA. 375 
to the mouth and tentacles ; the second, to the respiratory branchiz. 
With organs of the senses oysters are unprovided. Condemned 
to a sedentary life, riveted to a rock where they have been rooted, 
as it were, in their infancy, they neither see nor hear ; touch appears 
to be their only sense, and that is placed in the labial tentacles of 
the mouth. 
The mode of reproduction in these creatures is very peculiar. 
The oyster unites in itself the functions of both sexes. In the same 
organ are found the eggs—called sgaf—and the mobile corpuscles 
intended to fertilise ther. 
The eggs are yellowish in colour, and exist in prodigious numbers 
in each individual. We are assured that an oyster may carry as many 
as two millions of eggs! Nature always makes ample provision for 
the preservation of species ; but in spite of the most ample provision 
here displayed, man, in his reckless and wasteful gluttony, has all 
but defeated Nature. A tyro can compute how many individuals a 
bank of oysters reckoned at 20,000 would produce, at the rate 
of 2,000,000—or 800,000, as other authorities assert—from each one 
annually, and it will amount to an incredible number—in fact, each 
would multiply itself by millions in three years; and yet, thanks to 
our improvident management, oysters get scarcer every year. 
The spawning season is usually from the month of June to the 
end of September: during this season the oysters deposit their eggs 
in the folds of their mantle. During the period of incubation the 
eggs remain surrounded by mucous matter, which is necessary to 
their development, the whole having the appearance of a thick cream 
—this milky appearance being due to the accumulated mass of ova 
surrounded by the mucus: this mass undergoes various changes of 
colour while losing its fluidity, becoming successively yellowish, 
greyish, brown, and violet, a condition which indicates the near 
termination of the embryo state, for the oysters do not, like many other 
inhabitants of the sea, eject their ova; they incubate them in the 
folds of their mantle, and only discharge them when they can live 
without maternal protection. Nothing is more curious to witness 
than a bank of oysters at the spawning season. Every adult in- 
dividual of which it is composed throws out its phalanx of progeny. 
A living dust is seen to exhale from the oyster bank, troubling the 
water and giving it a thick cloudy appearance, which disseminates 
itself little by little in the liquid, until it dissipates and loses itself far 
from its focus of production. The saz is soon scattered far and wide 
by the waves; and unless the young oystér finds some solid body to 
which it can attach itself, it falls an inevitable victim to the larger 
