[51] OYSTER CULTURE. 803 
so as to enable it to part with the greater share of the mud which it 
carries. ; 
In order to prepare the ground of the claire for the reception of oys- 
ters, it must first be cleared of stones and all vegetation which may 
‘cover it, and then the necessary slope from the center towards the sides 
may be given it. The ditch is next dug and the yard thrownup. Then 
with the sluice-way made and the gate in place the claire is ready to be 
filled with water during the first high tide. When the basin is full the 
gate is closed and the water retained after the sea has returned to its 
ordinary level. Thesea-water soon penetrates the soil of the claire, satu- 
rating it with salt, destroying all injurious germs, and transforming it, in a 
word, into a marine bottom. Assoon as it is supposed that this effect is 
produced the gate is opened and the surface paved; that is, it is first 
smoothed over, and then pounded until it has the even, compact appear- 
ance of a threshing-floor. In about two months the bottom of the claire 
will be ready for the reception of the oyster. The breeders to supply these 
claires have, up to the present time, had recourse to oysters taken di- 
rectly from the sea, either from banks near at hand or along the coasts 
of Brittany, and brought in bulk in coasting vessels. In order that the 
products should be of a good quality and that the regimen of the claire 
should have a beneficial influence upon the oysters contained therein, it 
is necessary that they should not be older than from fifteen to eighteen 
months, or larger than from five to seven centimeters in diameter (about 
two inches). The breeder culls them, cleans them, chooses the best- 
shaped ones, and then scatters them with a shovel over the surface of 
the basin. Afterwards they are all arranged by hand so that nothing 
shall hinder their development or interfere with the opening of their 
valves. In this manner about 150,009 can be accommodated upon a hec- 
tare (about 2.41 acres) of surface. The claire is then filled with water, 
which is maintained at a uniform depth of 30 to 35 centimeters. This 
water, as has already been said, is renewed only at the spring-tides, 
and at this time the water in the claires is necessarily very much raised 
in level, and consequently the most active supervision is necessary, for 
the heavy pressure upon the dikes may produce breaks or fissures which 
it is necessary to repair immediately or widespread disaster may result. 
During cold or hot weather or sudden changes of temperature the 
breeders maintain the water in the claires at a higher level than the ordi- 
nary, in order to obviate the destructive action of the frost in winter or 
the rapid evaporation and heating of the water in summer. Neverthe- 
less, the construction of the claires does not always permit of accidents 
from these causes being guarded against, and sometimes the result is an 
enormous mortality and the ruin of the breeders. Moreover, the water 
by remaining in the same basin necessarily deposits there a certain 
amount of sediment which continually accumulates, being added to at 
each high tide, and especially during the equinoxial tides, thus placing 
the oysters in no slight danger. To remedy this evil, since it is impos- 
