692 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [101 
upper portion of the gills hang two pairs of furrowed folds, or lobes (the labial palps), 
between which is the mouth opening. The swollen upper portion of the body contains 
the generative organs, the liver, stomach, intestine, andheart. The bean-shaped organ 
near the center of the body is the adductor muscle, the so-called stool. This muscle 
which closes the valves consists of an upper grayish and a lower whitish portion. 
3.—THE REPRODUCTION OF THE OYSTER. 
If the surfaces of all the Schleswig-Holstein oyster-beds should be 
united together they would not cover a space equal to the one-hundredth 
part of that portion of the sea-flats which remain under water. Why 
is this? Isit because from a lack of oyster-broods all the places between 
the banks are yet to be peopled? I cannot accept this view for the fol- 
lowing reasons: The entire number of full-grown oysters existing upon 
the Schleswig-Holstein beds I estimate to be not far from five millions. 
According to my observations, 44 per cent. at least of these oysters will 
bring forth broods of young oysters in the course of a summer.* 
*The data from which I arrived at the conclusion that at least 44 per cent. of full- 
grown oysters spawn during each spawning season were derived from the following 
observations : 
These con- 
tained— e 
. ~ 
I opened on— H On | da 3 
So Nei a aeaeca lated 2 
enh (ieee vase hl vaca hale 
io) = fo | Seo} Ay 
shamed OUR 7a ed oo Seco va Saree on eae ee ee ee eee 112 | °5 |e 4 9| 8 
hUlye 6 S73 se Coates se ole cans ue Seance eee een ae coon nee nee eee 63 Uf 6 13 20.6 
AM HISt loli SOO ase cewees me teces eae 3 adem ise ietcarttatslsie ein aueenctaeie eee ASO i|(ctatatetaig eereteial= 72 15.8 
of Ae) 1) EARS ry Rr tes ee Oe AG IS BEBE a Heanee res eborlesacea|Seeese 44.4 
I do not know the length of time of development, from the beginning of segmenta- 
tion of the egg until all the embryos have passed out from the mother animal, but it is 
probably less than four weeks; for while, in the last weeks of May in the years 1871 
-and 1874, from June 4 to 6 of the year 1873, and June 6 to 9 of the year 1876, in hundreds 
of oysters which I opened, I found no embryos in the beard, yet of 112 oysters dredged 
on the 16th of June, 1873, five contained germs of a white color, and four contained 
germs already bluish, and possessed of shells and vela. 
If by the end of the first week in June no eggs have been laid, but by the beginning of 
the third week germs are found of a bluish color, then the transformation of the white 
germ into the blue cannot consume more than a week, and these germs will hardly re- 
main in the beard for an additional period of more than two weeks. Those oysters, 
then, which are found with eggs during each of the following months must be differ- 
ent individuals from those which spawned during the earlier periods; hence, it is right 
to add together the percentage of egg-bearing oysters found separately in June, July, 
and August in order to arrive at the percentage of egg-bearers for the entire summer. 
And since many oysters are found upon the Schleswig-Holstein beds with germs of a 
bluish color in the mantle even in the beginning of September, then the percentage 
of 44.4 per cent. surely cannot be too high. Oysters are hermaphrodite. In a large 
number of oysters which I examined I found ova in the generative organs, but no 
