708 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [3G] 



ing of the oyster takes place so readily and so rapidly as liere. There 

 are divers opiuious as to what causes we must attribute the change 

 which occurs in the color of the mollusk in the month of September. 

 Some think that it is due entirely to the clayey soil of Marennes, to the 

 brackish waters of the Seudre, or to oxide of iron. Others are as well 

 assured that it is to be attributed to a sort of vegetation which covers 

 the claires at the approach of winter, and disappears in the springtime. 

 According to them, the oyster owes its color to the absorption of the 

 chlorophyll with which the waters of the claires are saturated. A fact 

 of common observation is that the oyster takes on its green color when 

 the claire becomes green, and loses it as soon as the claire is deprived 

 of its vegetable growth. 



Although Marennes is very near Ol^ron, the experiments in reproduc- 

 tion which have been attempted there have not given any satisfactory 

 result. This is not, as certain of the cultivators {eleven rs) assert, be- 

 cause the captivity of the oyster impairs its generative faculties. The 

 oyster, whether it be in claire or pare, emits its spawn in the spriug. 

 We must, therefore, believe that the spawn does not encounter in the 

 water of Marennes, heavily laden with earthy matters, and perhaps too 

 sluggish, the conditions necessary for its existence. 



The areas under cultivation comprise viviers, depots, and claires. The 

 viviers are small establishments, having an area of about 400 square 

 meters, surrounded with walls of dry stone 20 centimeters in height, 

 situated upon the strand, and submerged by the sea at each tide. The 

 dS2)6ts are established upon the muddy flats along the shore. They are 

 inclosed by branches of tamarind stuck in the mud, which also serve the 

 purpose of showing the lines of demarkation between diflt'erent propri- 

 etors. The claires are basins, from 30 to 35 centimeters in depth, exca- 

 vated along the banks of the Seudre. 



The earth which has been excavated from the bottom of these serves 

 to form a bank, the top of which is about one meter above the bottom 

 of the reservoir. They are divided into deep and shallow claires. The 

 shallow claires, placed nearer to the shores of the Seudre, receive the 

 water more frequently. The deep claires, being further from the shore 

 and excavated in a surface which is more elevated, receive fresh water 

 but four or five days each spring tide. 



The greater number of the claires are surrounded with a ditch, which 

 is independent of the supply canal, in which they throw the muddy de- 

 posits which the sea brings in. 



As I have already said, the deepness of the claires varies from 30 to 

 35 centimeters, but in the autumn the depth of water maintained is 

 only from 24 to 30 centimeters. When the cold weather approaches 

 their depth is increased, for the frosts and the snow are very much to 

 be feared, and if the reservoirs chance to become covered with ice it is 

 immediately broken up. 



The shallow claires become green first. This condition lasts from the 



