4 
of my first experiment, I learned by the microscope that the* 
attempt at artificial fertilization was successful, and that 
nearly all of my eggs had started on their long path towards, 
the adult form. 
I made careful microscopic examination of the gills and 
mantles of all these oysters, but neither at this time nor after- 
wards did I find any fertilized eggs or young inside the parent 
shell, although I examined more than a thousand adults dur- 
ing the season. During the summer I found females with the 
ovaries so distended with ripe eggs that they were oozing 
from the openings of the oviducts ; others where the ovaries 
were half emptied, and others which had discharged almost 
all their eggs, and others at all the intermediate stages, but 
in no case did I find a single developing egg inside the shelf 
of the parent. 
I have accumulated enough evidence to show beyond the 
possibility of doubt, that so far as the oysters of the Chesa- 
peake Bay, during the summer of 1879, are concerned, the 
eggs are fertilized outside the body of the parent, and that,, 
during the period which the young European oyster passes 
inside the mantle cavity of its parent, the young of our oyster- 
swims at large in the open ocean. 
While this evidence cannot be regarded as sufficient to* 
show that the young of the American oyster are never car- 
ried by their parents, it is certainly enough to show that this 
cannot be assumed from the analogy of the European oyster. 
Most of the popular treatises on the use of the microscope- 
state that during the summer young oysters may be found 
inside the shells of the old ones, and as the number of ama- 
teur workers with the microscope in this country is quite 
large, I should be glad to learn whether any one has ever 
found this to be the case with American oysters. 
Until some such evidence is produced it is fair to conclude 
that my results are to be applied to all the American oysters^, 
and that there is a very important difference between them 
and the European species. 
