458 
POPULAR SCIENCE REVIEW. 
stratum of material which had lain without much adhesion 
on the tile with moveable cement.* 
Both of the above methods are still adopted, but that in 
which tiles are the medium is the most general. The tiles are 
usually mounted on posts driven into the sea-bottom, the 
object of this arrangement being to prevent the accumulation 
of mud and silt. The simplest form of tile collector is that 
which consists of a number of tiles placed upon horizontal bars 
and retained in situ by means of heavy stones. (PI. XVIII., 
fig. 1.) Figure 8 shows a variety of the first form, resulting 
from a combination of two. Fig. 7 illustrates another 
variety where the tiles are arranged obliquely, and in an 
overlapping manner, whilst in fig. 2 we have represented 
a collector in which the tiles are placed against each other 
like the rafters of a house. The cement in each case lines the 
concavity of the tile, and the numerous currents drag the 
embryo oysters along, and allow them to become attached 
to it. 
The end to be gained by all these different apparatus is the 
same — the collection of the young. This, however, is not the 
only thing to be effected : after the oyster has been detached 
from its temporary resting-place, it must be fed and fattened. 
How are these processes carried out ? Along the foreshores 
there are constructed reservoirs of a certain depth, and with a 
firm bottom. These are provided with sluice-gates, and 
are so arranged that when the tide retires, the water is 
retained. In these reservoirs the young detached oysters are 
carefully laid, convex side downwards, and there they are 
allowed to remain, feeding upon the abundant vegetable 
matter, and luxuriating in the increased temperature, till they 
have grown large enough for the market. These processes 
are fundamentally what the French have carried out, though 
of course, in many instances, with considerable modifications, 
whose description would be out of place here. The results 
have been incontestably successful. The increased supply of 
oysters in the once exhausted beds of Rochelle, Marennes, 
Rochefort, and the Bay of St. Brieuc, is a fact sufficiently 
corroborative of the truth of this statement. But the most 
convincing evidence of all is that afforded by the Island of Re. 
Five years since , the shores of this island were barren and un- 
cultivated ; noiVj they give employment to 3,000 men , and the 
crop which was produced in 1861 ivas valued at £320,000 
sterling. Nothing could be more satisfactory than this achieve- 
* The moveable differs from the fixed cement in being attached to the 
edges only of the tiles, though spread over their surface. Both forms are the 
same chemically. 
