OYSTER-CULTURE IN FRANCE. 
371 
COATING WITH CEMENT (CHATJLAGE). 
Early in the spring each proprietor causes his collectors to be thorougly sun-clried. 
The cement vat is then prepared with a mixture of lime and sea water, often with a 
proportion of sand or mud stirred to the consistency of thick cream. The collectors 
are rapidly dipped in this limy fluid, allowed to drain off, arranged on rough trays, and 
set aside for several days to thoroughly dry. The cement crust should then be about 
a millimeter in thickness, somewhat brittle, separating from the tile in flakes. The 
dipping of the tiles in cement is sometimes performed by hand, sometimes by means 
of a well-sweep. The operation is a rapid one, the attendant women on one side of 
the vat passing up the tiles separate or in bunches, as in bouquets , for immersion; 
another detachment promptly removes the moist collectors and spreads them to dry. 
A new tile is first saturated with a watery mixture of quicklime and water, to fill the 
pores in its spongy substance. It is then dried and subjected to the regular process. 
Of the properties and ingredients for chantage each proprietor has his own recipe. 
At Arcachon the formula is in general that of M. Daste: one part quicklime, three 
parts fine sand, with coloring matter sometimes added. In the region of Auray, M. 
Martin gives his tiles a double liming, first with a light coating of quicklime, and sec- 
ond, after the tiles have dried, Yvith one of hydraulic cement. In the Trinitd River 
region, M. Leroux prepares a mixture of one part quicklime and one part of fine gray 
mud, as best suited to his locality. 
PLACING AND MANAGEMENT OF COLLECTORS. 
In localities where spat collection is naturally favorable, as at Arcachon and in 
the region of Auray, the tide limits along the beaches will be seen covered with col- 
lectors (Plate lxx, Eig. 1). These are most numerous near the low- water mark, usually 
arranged in close regular order, but with alleyways between leading shoreward, wide 
enough for the passage of a cart or boat. In placing collectors it is usually arranged 
so as to allow the current to run counter to the length of the tile, in order thereby to 
gain nodes of still water under each tile as places of refuge for the young oysters. It 
is claimed, however, that this precaution is a needless one. The matter of the great- 
est importance, universally conceded, is when the collectors should be put in place. 
Experiments have shown that in localities of French production the placement should 
be arranged during the low tides of the last week in June and of the first fortnight 
in July, and that the bulk of the collectors should be in position by the commence- 
ment of July. The question of time is carefully studied by the culturist. He exam- 
ines the oysters from time to time, looking for the gray spawn, the nurslings which 
the oyster is about to eject. As long as the spawn is white or creamy in color the 
culturist defers the placing of collectors. As the collectors so speedily become slime- 
covered, the question of a few days is regarded as of the greatest importance for the 
success of the set, since the major portion of spawning is found to take place quite 
suddenly. The anxiety of the culturist in regard to exactness of time seems one that 
should be carefully considered at home, for the habits of the fry appear to be very 
similar to those of our own, especially as it is now conceded that the swimming stage 
of the European species lasts for several days, or even a week. 
The set once obtained, there is nothing to do but wait till growth has rendered 
the young large enough to be safely separated from the tile. They have attained by 
