When the embryos are at this stage their number may be estimated in the
following manner: The whole mass of embryos is carefully scraped from
the beard of the mother oyster by means of a small hair brush. The whole
mass is then weighed, and afterward a small portion of the mass. This
small portion is then diluted with water or spirits of wine, and the
embryos portioned out into a number of small glass dishes, so that they
can be placed under the microscope and counted. Thus, knowing the weight
of the small portion and the number of embryos in it by count, we can
estimate the total number of embryos from the weight of the entire mass,
which is also known. In this manner I estimated the number of embryos
in each of five full grown Schleswig-Holstein oysters caught in August,
1869, and found that the average number was 1,012,956.
Notwithstanding this great fecundity, but an extremely small proportion
of the young oysters produced during the course of the summer arrive
at maturity, 421 only out of 500,000,000 escaping destruction.
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