_The Propagation of Oysters._--At the recent meeting in this city
of the American Fish Cultural Association, a paper was read on the
propagation of the oyster, by Dr. W. J. Brook, of the Johns Hopkins
University. The manner in which this propagation takes place had never
before, he said, been thoroughly understood. Through studies made by
him last summer, however, great light was thrown on the subject. He
found that the American oysters do not breed their young in the
shell, as had been supposed, and that consequently the eggs can be
impregnated artificially. An average oyster contains from six to nine
million eggs, and one of large size may contain fifty millions. The
plan pursued by him in fertilizing these eggs was to chop the male
and female oyster up together; thus the fluids are mixed and the
impregnation is made complete. The process of development immediately
begins, and goes on so rapidly that a change may be noted every
fifteen seconds. In a very few hours the embryo is sufficiently formed
to swim in the water. The shells at first are very small, and are not
adjacent to each other. They grow very rapidly, closing down over the
sides, and finally unite and form the hinge. In the short space of
twenty-four hours the young oyster is able to take food, and from
three days to a week it attains perfect form. During its early life it
is a swimming animal. The oyster is able to reproduce its species at
the end of a year's growth, and it is marketable at the age of three
years.
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