762 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [10] 
tion of its structure we will pass at once to the study of the phenome- 
na of reproduction, which have for us a very important significance. 
The oyster is hermaphrodite* ; that is to say, each individual contains in 
itself the organs of both sexes—the ovary, or egg-producing organ, and 
the testicle, or organ for the formation of the male element or spermato- 
zoa. This question, which for a long time was the subject of debate, 
is now entirely settled (MM. Quatrefages and Blanchard sustained the 
contrary opinion, and several memoirs read before the Academy of 
Sciences treat of the artificial fecundation of the eggs and the artificial 
formation of oyster beds). It is recognized that in every individual are 
to be found at the same time both eggs and spermatozoa, and that, more- 
over, the eggs present all the phases of fecundation before they have left 
the ovaries of the animal and have reached a place where an external 
impregnation could be possible. One should not think, therefore, of 
artificially impregnating the eggs of the oyster, for this would require 
the removal of the eggs from the ovary of the mother while in course of 
development, which would be incompatible with an independent ex- 
istence.t 
The spawning season of oysters lasts about three months, from June 
to September. The eggs are produced in the ovary,t which is situated 
deep in the body of the animal, and whence, after they have arrived at 
a certain stage of maturity and have been impregnated, they descend 
along spacious canals into a fold of the mantle, where they remain in- 
closed in a mass of mucus, until they have completed their develop- 
ment. The eggs form at this time two whitish, creamy masses, which 
increase the size of the oyster very much, and cause it to be much sought 
* This is without doubt not true so far as regards the American oyster (Ostrea Vir- 
giniana). I have examined, under the microscope, hundreds of oysters during the last 
two years, and throughout nearly the entire spawning season as late as the middle of 
October, and never in a single instance have I found any evidence of hermaphro- 
ditism, the sexes always being well marked and perfectly distinct. Neither have I 
seen any evidence of the development of the egg until after it had passed from the 
ovary and come in contact externally with the floating spermatozoa; from my own 
observations, and from those of accurate observers with whom I am acquainted, I am 
of the opinion—which coincides with that of Quatrefages and others as to the Eu- 
ropean form—that the American oyster is as truly unisexual or dicecian as any mam- 
mal.—(Tr. ) 
tNotwithstanding this statement in regard to the oyster in general, Prof. W. K. 
Brooks, of the Johns Hopkins University, Baltimore, Md., has succeeded, during the 
past summer of 1879, at Crisfield, Md., in successfully impregnating great numbers 
of eggs of the American oyster. The impregnation was effected by taking the ripe 
eggs from the ovary of the female and mixing them artificially with the spermatozoa 
taken from the male animal. Many others of the party, of the Chesapeake Zoological 
Laboratory, including myself, also succeeded with the artificial impregnation, and 
there is no question but that such a process can be successfully performed, although 
to what extent it is practicable is a question yet to be settled.—(Tr. ) 
{ The statement of the author in regard to hermaphroditism and its results, and the 
changes undergone by the eggs within the ovary, must, in all probability, be consid- 
ered as entirely erroneous.—(Tr. )- 
