102 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



time of my visit (July 3rd and 4th) which was just the 

 period when the free-swimming embryos were settling 

 down, the water over the pares seemed to be swarming 

 with them, and the spat was making its appearance all 

 over all sorts of suitable submerged objects. 



The great importance of Arcachon in oyster culture is 

 undoubtedly as a place where the adult oysters reproduce 

 freely, and where the free-swimming larvae or "fry" when 

 settling down as spat can be readily collected and so be 

 saved from destruction and made available for artificial 

 rearing. The oyster chiefly cultivated at Arcachon is 

 Ostrea edulis the ordinary rounded flat oyster of Northern 

 Europe, but the large elongated Portuguese oyster, Ostrea 

 angulata, is also abundant at Arcachon and is said to be 

 increasing. There was some alarm recently amongst the 

 oyster proprietors upon the ground that these two species 

 were breeding together and producing an inferior kind of 

 hybrid. This fear has however been dispelled, as it is well 

 known to biologists that the reproductive arrangements 

 in the two species are very different. A much more 

 practical, and in fact quite likely, difficulty would ensue 

 if the Portuguese oysters became so numerous in the 

 "bassin," that their fry would come into competition 

 with the fry of Ostrea edulis in settling down on the 

 "collectors," and being, it is said, more hardy animals 

 would oust the latter is the struggle for existence. 



The oyster reproduces at Arcachon between May and 

 the beginning of July and the young animal leads a free- 

 swimming existence for nearly a week before settling- 

 down. The cultivators (" parqueurs ") examine carefully 

 the condition of the spawn in the old oyster and at what 

 they consider to be the proper time (generally about the 

 end of June) for catching the deposit of spat, or young 

 oyster ssettling down after the free-swimming existence, 



