80 Our Food Mollusks 



European oyster beds. The idea was to cover the tiles 

 with a crust of some substance that could easily be re- 

 moved after the oysters had become fixed to it. After 

 some experimenting, a cement was invented that an- 

 swered all requirements, and it is in use all along the 

 coast to-day. It is a mixture of quick-lime and sea 

 water to which is added enough fine sand or mud to give 

 it the consistency of thick cream. Into this, dry tiles are 

 dipped, and coated with a layer of the mixture having a 

 thickness of about a millimeter. The coat is thoroughly 

 dried before the collector is placed in the water. After 

 several weeks of immersion, it softens somewhat by the 

 action of the sea water, and, though still firm enough to 

 adhere while the tile is being handled, it flakes off 

 readily in the process of removing the young oysters. 

 This is effected by means of a flat knife-blade. When 

 the crust bearing the spat has thus been removed, the tiles 

 are stored to be coated and used again during the next 

 spawning season. In this way the same collectors are 

 used for several years. At Arcachon and Auray it is 

 estimated that each tile annually affords attachment to 

 about two hundred oysters. 



The spawning season is not sharply limited. As in 

 the case of the American oyster, some young appear in 

 the water at almost all times of the year. But the great 

 majority are produced in the early summer, and it is a 

 matter of great importance to the French culturist to 

 determine the time of their appearance. If tiles were 

 immersed for any length of time before spawning be- 

 gan, even their concave surfaces would become so con- 

 taminated with slime, that attachment would be inter- 

 fered with. Salinity of the water, temperature, and 

 other conditions that vary from year to year, determine 



