226 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



the New World, wliicli, owing to their sexuality, are, like the Portuguese 

 oyster, suitable for artificial reproductiou, aud are in many respects, 

 especially as regards their flavor aud size, superior to the Portuguese 

 oyster. 



The following has been the endeavor of our researches during this 

 year : 



1. To find out whether artiticial fecundatiou could yield i)ractical re- 

 sults ill entirely closed waters; and 



2. To ascertain whether the raising of the Portuguese oyster is possi- 

 ble and i)rofltable in the ponds on the Mediterranean. 



To begin with, it should be stated that it appears from observations 

 made both on the coasts of the Mediterranean and of the Atlantic Ocean 

 that aeration, a constant renewal of the water, and also its agitation, 

 are necessary for succeeding jn certain cases, especially when the tem- 

 perature is high. Up to a certain point, heat favors the hatching of the 

 eggs and the development of the embryos produced from them ; but if 

 it passes this point, it causes the rajiid decomposition of the generative 

 elements and the death of the young embryos. To oi)e!at(3 under such 

 a condition will almost certainly result in failure. 



The majority of the experiments made during the last seasou have 

 proved this beyond, dispute. At Verdoii these experiments were made 

 in the salt marshes where wo liad previously been stationed. We had 

 purposely isolated one of the experimenting reservoirs, so that the fresh 

 water of the tide coukl not get into it. In this closed reservoir, there 

 were jdaced, at different intervals, the fecundated products of at least 

 a hundred male and female oysters; while in a larger reservoir, which 

 received fresh v.ater at every tide, there was i)laced the fry of only a 

 dozen breeders. The result was that the collectors placed in the closed 

 marsh remained free from si)at, while each of the tiles placed in the 

 reservoir, where the water entered and flowed off freely, contained from 

 thirty to forty young oysters. This may to some extent be explained 

 by the want of aeration and agitation, but it must be attributed prin- 

 cipally to the high tem])erature of tlie water. In fact, when the em- 

 bryos were ])laced in tiie reservoir, which was at the time when the 

 most intense heat of summer sets in, it was found that there was a con- 

 siderable ditference between the temperature of the water in the open 

 reservoir and that of the closed one. Similar observations were made 

 at Cctte and at Berre, in the reservoirs which the Southern Salt-Works 

 Com])any had kindly i)laced at our disposal. 



We must here give an important observation, made on the shores of 

 the Mediterranean, relative to the forwardness of the oysters raised in 

 the waters of the south as regards reproduction. We found that the 

 oysters transferred last year from Verdon to the pond of Thau and the 

 pond of Lattes were capable of propagating at the end of May. Arti- 

 Jicial fecundation attempted at this period produced ninety lively em- 



