880 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [56] 
PAVING-STONE COLLECTORS. ° 
Oyster spat is also gathered upon blocks of stone, such as are some- 
times used in parks; this practice obtains in the neighborhood of La 
Rochelle, and notably at Laleu and the isle of Ré. | 
These stones, irregularly and obliquely arranged one against the 
other, serving for mutual support, should form numerous winding cay- 
erns, Whose arches are protected from mud, and afford numerous large 
spaces where the young oysters may fasten themselves. 
The paving-stone collectors can be constructed at small cost, and each 
one of them offers. also, the advantage of accommodating two crops; 
all that is necessary to accomplish this is simply to return the blocks 
to the same places from which they were taken, and arrange them as 
nearly as possible in the same position as they originally occupied. 
By this operation the oysters fastened to the lower surfaces are placed 
in a full light, which is a most favorable condition for their growth; 
while the upper surface of the stones, when reversed, furnishes to suc- 
ceeding generations shelter and an excellent surface for their adherence. 
But while these paving-stone collectors offer incontestable advantages, 
they are also open to grave objections, made evident by experience. 
The oysters are apt to fasten one whole side of the valve to the stones, 
and hence cannot be removed except with great loss; and then again, 
those that are not attached in this manner are liable to contract defec- 
tive shapes. 
It is not only necessary that large quantities be produced, but also 
that the product may be easily gathered, and that the oysters have a 
desirable form. 
