National Republican., 1883-10-26
OYSTER CULTURE.
Interesting Experiments on Rearing Oysters
from ArtfCially Fertili2ed Eggs
Report OF MIR. John A. Ryder, EmbryoIo-
gist OF the Fish CommIssion.

United states fish commission, who was as
signed to investigate that subject several
months ago. Tho paper states that the de-
STABILITY Of testing the breeding of oysters in
ponds in the United States as practiced for
many years in France has long been been q
desderatum. In order to test the feasibility
OF such method on scale large enough to
give practical results, an arrangement to
carry out such scheme was finally effected
with the Eastern Shore Oyster company. A
pond was excavated in the salt marsh ON the
shore of Chinooteague bay, Maryland. This
pond covered an area of about so square yards
and was connected with Chesapeake bay by q
trench or canal about 10 feet in length, g feot
wide, and 81 feet in depth, tho same depth
as the pond itself. The water supply for the
pond was filtered through permeable porous
gate, which was placed in the trench con-
Meeting the pond with the bay, and no water
was allowed to enter the pond which had not
been first filtered through the porous gate.
The latter was constructed of boards por.
forated with augur holes and lined on
the inside with gunny cloth or sack
ing, and the space between the perforated
boards filled with sharp, clean sand Through
this space the tide ebbed and flowed, giving u
successive tides. This apparatus constituted
the receptacle into which the artifcially fer
tilized eggs of q number of oysters were in
troduced every two or three days. Tests were
made, and it was discovered that tho tempera-
turo and specific gravity of the water in the
pond remained tho same as that Of the bay.
Another question arose, which was whether
o sufficient amount Of food would be generated
in the pond TO supply any young
or old oysters with nourishment. The pond
water, however, soon acquired a distinctly
brownish green tint Amicroscopical investi-
CATION of the water showed that the brown
color was innumerable microscopical plants
consisting largely of diatoms, having brown
ish contents. Monads and other oyster food
were found in the pond greatly in excess of
what may be found in the open bay, Thus
the most important conditions of the success
of the experiment was established, as the
final results afterward confirmed, for spat
grew just as rapidly in the pond as In the
waters of tho bay, and there is no reason to
suppose that the pond spat would not grow to
marketable size just rs certainly as the spat
collected in the natural way.
The collectors used in our experiment were
of the simplest possible character, the object
being TO make the experiment as practical rs
possible. Stakes were driven into tho bottom
of the pond, extending above the surface
some distance. to which oyster Shells with
holes punched through, were attached after
being strung upon galvanized iron wire. A
number OF these simple collectors were
placed in the pond, each set being marked
with tho date on which they were placed in
position, in order to afford date for a more
detailed study Of the results of the expert
uent
The oysters used for the purpose of spawn
ing were taken from the Vicinity of the
oyster house, and others were obtained from
the deeper waters of the bay. The eggs from
hnl .
readily fertilized as those from tho deeper
water, and an abundance of good spawn was
obtained until the latter part of July.
Tho oysters from which spawn was OBJ
tanned were carefully opened by removing
the right valve and allowing the soft parts OF
the animal to remain attached by the muscle
to tho left one. The spawn itself was
then pressed out of the generative organs
by means of q pipette gently stroked
over the gland and out along the course of
the etferent ducts, so as to force tho spawn
out into the upper gill chamber. The sexes
were distinguished apart very easily by the
drop test" which consists simply in drop-
ping the spawn from pipette into dish of
clean sea water and watching the kind of
cloud which it forms after it strikes the
water Invariably, If the specimen was a
female, the eggs would break up into gran
ular cloud, which could be very readily
seen to be composed of very minute
was hold up so as TO look
down through it upon dark ground
below. In case the specimen was u male the
drop of milt would not so readily break up
hut would exhibit somewhat glairy consist
ency; and if the drop was stirred in the water
1t would break up into wisps and streaks, SO
as to appear on u small scale like q series of
minute mares tail clouds, such as are seen In
the sky at times, This test is SO practicable
and simple that novice can easily distin-
guish the oyster sexes after one lesson. The
spawn so taken was mixed together in small
dish, thoroughly stirred together and poured
from time to time as the water be-
comes milky in tho small glass
collecting vessel into wooden pail and then
poured into the pond at different points in
order to distribute it over as great an area as
possible.
Forty-six days after the beginning of the
experiments, several of the oyster shell col
lectors were takon out Of the pond and young
oysters or spat found attached to them, rang
ing from one-fourth to three.fourths of an
inch in diameter demonstrating that the
young would grow just as rapidly in the pond
as in the bay,
I'VE are therefore prepared to assert," says
the report, that 1t is perfectly feasible to
rear oysters from artifcially fertli2ed eggs,
and SO far as l can judge, quite as successfully
as by the method of sowing shell on the bot
tom, now largely practiced on the coast of
Connecticut in the waters of Long island
sound. While our experiment has not shown
that we could get greater set of spat than
that ordinarily obtained under natural con-
ditions on planted shells, the experiment has
settled several questions which are of the
greatest Importance in the practical work OF
oyster culture"
The young oyster depends largely for food
On the very low and minute forms. In fact,
II Is possible TO frequently find young oysters
in the stomachs ofwhich multitudes Of minute
plants are rotating under the impulse of the
! vbratile ella with which the stomach is
! lined the stomach itself being q cavity not
over the one-four- thousandth part of an inch
in diameter, which will give some idea of the
minuteness Of tho food required to nourlsh
30 tiny u creature.
The practical utility of the experiment
proves that ponds or inoosed areas of water
may be readily utilized on tho eastern coast
of the Unitod States for cultivating oysters
in the same way rs Is practiced in France
and other European countries. There are
many thousands of acres of salt marsh all
along tho eastern coasts of Virginia Mary.
land, Delaware, New Jersey, and perhaps
New York aud Chesapeake, Delaware, and
Chincoteague bays, which could be readily
converted into permanent and profitable
planting grounds for the cultivation OF
oysters. The great advantage of this method
would be that the persons constructing the n-
closures and digging out ponds on their
own territory, would be absolutely protected
by law from the inenrsions of tho laWless