OYSTER AND MUSSEL REPORT. 131 



the same, the fauna both macroscopic and microscopic is 

 not appreciably richer, and although the temperature of 

 the water is certainly higher in the south, probably on the 

 average about 10°F. higher, still I do not think that that 

 is essential, and it may even be considered doubtful whether 

 it is much advantage. The opinions of the practical men 

 I met in France differed on this point. Mons. Daste at 

 Arcachon was convinced that considerable heat was 

 absolutely necessary for the successful breeding of oysters, 

 and that the greater the heat the better the deposit of spat. 

 It is not unnatural for the successful breeder of oysters to 

 be influenced — perhaps unconsciously — by the desire to 

 keep that branch of the industry as much as possible in 

 his own hands, and to think that the conditions found in 

 his district are essential, and that all that should be 

 attempted elsewhere is to rear the oysters he has pro- 

 duced. In opposition to that opinion we have the facts 

 that Capt. Dannevig has had oyster spat produced in 

 abundance in his pond at Arendal in Norway, and that 

 both on the north coast of France and the south coast of 

 England oysters reproduce and spat is deposited. 



Lately Prof.H. de Lacaze-Duthiers has proved that even 

 under artificial conditions in the aquarium of the Zoolog- 

 ical Station at Boscoff on the North Coast of Brittany, he 

 can bring seed oysters to a high state of development and 

 commercial value, and that the oysters will reproduce in 

 the aquarium, spat be deposited, and the young oysters 

 be readily reared up until they are fit for the market — the 

 entire life-history having been passed through in confine- 

 ment. I consider that this is an important observation 

 as there can be no doubt that under natural or semi- 

 natural conditions a very large proportion of the free- 

 swimming embryos are carried away by tides or currents 

 and either destroyed or lost to the cultivator. 



