[45] OYSTER CULTURE IN MORBIHAN. 987 
As to the special attentions to be observed, MM. Mauduy and Sol- 
minihac have briefly summed them up, in the following terms: 
‘We take great care of our parked oysters, because experience has 
shown that the more attention given them, the more satisfactory are the 
results. These cares consist mainly in removing all foreign matters, 
which the tides may deposit in the parks, in turning the oysters, in re- 
arranging those that are badly placed, and in repairing defects in the bot- 
tom, after which the oysters may be replaced upon it. These operations 
require the employment of a considerable number of workmen, all the 
year round.” 
The duration of the term of parking for an oyster of salable size, varies 
from six months to one year. There is nothing which more requires the 
eye of the master, and constant and active watchfulness. 
Results obtained ; turning green.—The results obtained are in propor- 
tion to the efforts Alien ed. The well-parked oyster upon our shores 
will assume a closed shell; while before parking it consisted of a chamber 
containing foetid water, which spreads throughout the interior when the 
knife is employed. This defect it' loses and assumes a solid and resist- 
ing surface. The oyster grows, its flesh loses its brown color and be- 
comes quite white. Everything indicates a Seale? for the better, as 
pleasing to the palate as to the eye. 
One quality, long considered as peculiar to the oysters of Marennes, 
a greenish coloration, is easily produced in the parks of Morbihan. 
This singular phenomenon consists in the appearance of a very decided 
greenish color, affecting especially the breathing organs, that is to say, 
the four branchial leaves. 
Coste had observed this fact at Marennes, and had also noticed that 
the green oysters always became white at spawning time. ‘ Those,” 
said he, “ which previously presented this appearance, became paler, little 
by little, as fecundation took place and finished by losing the color en- 
tirely, at the time of spawning. On the other hand, those which were 
white when placed in the parks remained so. It is only after the month 
of August, that they recover from this temporary loss of color, which 
does not affect the trade, since the color reappears immediately after 
spawning.” 
It is now proved that the process of turning green in the parks of 
Morbihan, is connected with the entrance of fresh water into the parks, 
and the development of vegetation upon the bottom. It is effected in 
a few days and has no relation to fattening. What causes the trans- 
formation? Some of our culturists attribute it to a disease of the liver, 
others exclusively to the influence of the bottom. 
Berthelot, who carefully analyzed the green oysters, thinks he can 
ascribe the green color to a metallic oxide, doubtless the oxide of iron, 
The blue marl of the Seudre contains analogous elements. This alone 
indicates that the bed, on which the oysters are placed, exercises so de- 
