ARTIFICIAL OYSTER CULTIVATION. 1169 



hence their widely extended use. The average cost is 

 per 1000, or about a halfpenny each, and there are more 

 than ten million in use on the crassats at Arcachon. 



The time for placing them in position varies according 

 to climate and locality. At Arcachon they are laid down 

 about the ist of June. At Auray the spatting season is 

 fully a month, and sometimes six weeks later ; so the tiles 

 are not in position much before the middle of July. But 

 these dates, of course, depend a good deal on the season. 

 The bottom of the sea in the immediate vicinity of the tiles 

 is generally strewn with clean culch. 



The methods of arranging the tiles depends upon the 

 position in which they are placed. In the large flat pares 

 at Arcachon they are placed in rows or patches, on the 

 beds which are dry, at low spring tide. The tiles are laid 

 in stacks, crosswise one row above another, till the height 

 of three or four feet is reached ; they are then secured from 

 the run of the tide by stones and stakes. The weed around 

 them is hoed away for a few yards, and the oysters are laid 

 down. The greater portion of the spat is found adhering 

 to the under surface of the tile. It is an unsettled question 

 as yet whether this is merely because the concave surface 

 is cleaner, or whether the oyster does or does not spat most 

 often on the flood tide, in which case the spat would adhere 



in rising. 



The tile crates are erected about every twenty yards, 

 and arranged alternately, or, as the French say, en quinconce, 

 so as to break the flow of the tide evenly, and thus catch 

 most spat. The top of the crate is often protected by planks 

 coated with pitch, on which culch has been strewn before it 

 is dry ; these coverings often catch a lot of spat. Where 

 there is no tide, or the ebb and flow are equal, it is recom- 

 mended that the tiles should be placed at an angle, as they 



