I I 70 OYSTERS, AND ALL ABOUT THEM. 



have then been found to attract the greatest quantity of 

 spat. The system of laying down tiles has been abandoned 

 at Auray on account of the rapidity with which they become 

 covered with mud. 



M. Leroux has substituted a plan of suspending the 

 tiles on an iron wire, which is firmly strung between two 

 posts fixed in the ground. This seems to answer well, and 

 has the further advantage of being easily taken up and 

 laid down ; twelve or fourteen tiles are thus placed on 

 one wire. (b] 



Writing on tile collectors, Dr. Brooks says : 

 Those which are used in France are much like a common 

 drain pipe, sawed in two longitudinally. . . . Each 

 tile is about 18 inches or 2 feet long, 6 or 8 inches wide, 

 concave on one side and convex on the other. The shape 

 of the tile is important, as nearly all the oysters fasten 

 themselves upon the concave surface. They adhere so 

 firmly that it is difficult to detach them without injury, and 

 to avoid this the French oyster breeders coat the tiles with 

 a thin whitewash, which can be scaled off with the young 

 oysters when these are large enough to be distributed upon 

 the planting grounds. 



The following is an account of the method of coating 

 the tiles as employed in France : 



" What is most remarkable concerning liming is the fact 

 that both quicklime and hydraulic cement are decomposed 

 by sea- water. Hydraulic cement hardens in fresh water ; 

 but salt water, although it permits of a first hardening, in 

 the course of time produces complete decomposition. 

 This change is favourable to the removal of the young 

 oyster, and to the assimilation of lime by the young." 



(b) Anson & Willett's ' ; Oyster Culture," pp. 65-80. 



