52 
about 1:022 to 1:024, and Dr. Bashford Dean and others 
state as their opinion that a low specific gravity is neces- 
sary for a good deposit of spat. I asked Mons. Dasté his 
opinion on this point. He has had great experience as a 
practical ostreo-culturist and has moreover been in the 
habit of taking temperatures and specific gravities. He 
said that unusually low specific gravities (due to wet 
weather) during the breeding season did harm at Arcachon, 
while further north at the other end of the‘‘ bassin”’ they 
did good and resulted in more abundant spat because of 
differences in the local conditions. 
Therefore it can scarcely be predicted for any particular 
place whether a high specific gravity of the sea water will 
or will not be advantageous for oyster culture. On the 
whole Mons. Dasté thinks that salter water is better for 
breeding and for the growth of the shell (‘‘ coquillage’’) 
but that less salt water—some admixture of fresh from 
springs or streams—is better for the growth of the animal 
(the soft parts in contradistinction to the shell) when one 
or two years old. Certainly the French wild oysters that 
I came across attached to rocks at low tide on the shores 
of the open sea, although their shells might be well grown, 
had the animal meagre, stringy, and saltish to the taste 
and wanted the fatness and flavour of those reared in 
*“elaires. 
At Arcachon the young oysters are allowed to remain 
on the tiles at least till October or early in winter, when 
they are about the size of the finger-nail, say } to inch 
in diameter (see Pl. II, fig. 1). Then the tiles are collected 
and taken ashore and the process of ‘‘ détroquage”’ or 
separating the oysters from the tiles takes place. This is 
effected very rapidly by a skilled hand, the little oyster 
with the film of lime to which it is attached being flicked 
off the tile rapidly by a square-ended knife. 
