ARTIFICIAL OYSTER CULTIVATION. 1183 



cleaned if only affected by outside growth, and mussels, 

 starfish, and vermin of all kinds brought ashore and thrown 

 away. When returning the healthy oysters to the water, 

 they are sorted as far as possible, so as to be more readily 

 got at during the coming season. Oysters separate much 

 more easily in summer than in winter. If the cultack be 



J 



freely or carelessly used during the cold weather, oysters 

 are apt to rob one another, i.e. to tear away pieces from each 

 other's shells. 



The Whitstable people have an idea that constant 

 dredging tends to fatten oysters by bringing them into 

 contact -with a wider food area, and this opinion, we think, 

 is not contrarv to that of the most experienced Essex 

 merchants. 



TANK SYSTEM OF CULTIVATION. 



t 



The pares at Marennes are situated on both sides of 

 the river Seudres ; they are not, like those at Arcachon, 

 submerged every rise and fall, but only at high spring-tides. 

 Each claire, or tank, is about thirty yards square, and they 

 are so arranged that a certain number can be laid aside for 

 cleaning whilst the others are in use. The walls for retain- 

 ing the water are low banks of earth about five feet thick 

 and three feet high. The tide is admitted by water-tight 

 sluices, as it is considered most essential to be able to regu- 

 late the inflow and outflow of water with the greatest exac- 

 titude. A trench is cut on the inside of each pond so as to 

 collect the green slime necessary for the production of the 

 green fins, and some considerable trouble is required before 

 the tanks are fit to receive the oysters. 



The preparation of a reservoir for the reception of 

 ovsters, called in French le parage, takes place in March. 

 It consists of two operations: i. Called le gralage, which 



