AQUICULTURE 283 



its numerous natural enemies, such as the boring sponge 

 (Cliona), which ruins the shell; starfishes and crabs, which 

 manage to suck or pick out the soft animal ; and whelks 

 {Purpura and Nassa) and other Gastropods, which can bore 

 a hole through the shell and prey upon the oyster within. 



The ambulances are constantly looked after by the oyster- 

 men, and especially women, who come at low tide, when 

 the " caisses " are exposed, open the lid, and pick over the 

 contents, removing any enemies or impurities which may 

 have got in, such as crabs, taking out any dead shells, and 

 rearranging the oysters, if necessary, so that all may have 

 a fair chance of obtaining food and growing normally. The 

 young oysters grow rapidly iu the ambulances, and have 

 soon to be thinned out. The larger ones are removed to 

 other ''caisses" — or, if large enough, they are thrown into 

 the open enclosures or little fields of the pare. Additional 

 young ones may now be added, or all the space may be 

 required for a time by those left. In this way, by thinning 

 out, rearranging, and adding, relays of young oysters in 

 their first year may occupy the ambulances for eight months, 

 although an individual oyster may only be in for one month 

 or so. Eventually all the oysters not sold to " eleveurs " or 

 exported get transferred from the ambulances to the field- 

 like enclosures of the pare (PI. XXV). 



During the last half-century the number of oyster-pares 

 at Arcachon has varied from about 3,000 to 6,000. The 

 number of oysters exported in the year has generally varied 

 from about 300 million to 500 million, and the value from 

 about a milhon francs upwards, according to the current 

 prices for oysters. 



The whole of this prosperous industry, both at Arcachon 

 and elsewhere on the coast of France, was started between 

 1859 and 1865, by a professor of biology, M. P. Coste, 

 who, instigated by the Government, made investigations 

 and experiments, and is said to have imported Scottish 

 oysters from the then flourishing natural beds in the Firth 



