OYSTER CULTURE IN FRANCE. 613 



never found one in which the sex was doubtful. They 

 were all either exclusively male or exclusively female. The 

 difference is also equally great in the mode of reproduction. 

 The eggs of the ordinary oyster are fecundated in the interior 

 of the valves, apparently in the generative orifices ; those of 

 the Portuguese are so in the water. The former cannot 

 develop themselves out of the incubating cavity ; the latter 

 can do so in the open current. The larvae of the edulis 

 must, to live, form themselves, and attain the period of 

 their roving existence out of the albuminous liquid secreted 

 by the parent ; those of the angulata, which are more 

 vigorous, independent, and sooner able to move, carry in 

 themselves or obtain, in spring tides only, the elements of 

 nutrition and constitution, which are necessary for their 

 transformation into spat. 



HYBRIDATION OF OYSTERS. 



There are, then, between the Tagus oyster and that of 

 our coasts very great differences, as much in point of con- 

 chology, or the exterior, as in the internal soft arrange- 

 ments, and especially in point of embryology. The cha- 

 racters peculiar to each are so strongly marked that had 

 they been well known the question of hybridation, which 

 has so thoroughly alarmed our maritime population, would 

 not have been raised. It will be remembered that, accord- 

 ing to a theory advanced by some parqueurs, the two rival 

 oysters are capable of being crossed. 



The Portuguese oyster, on the one hand, was said to 

 debase the race of our own fine oysters, and, on the other, 

 in consequence of its vitality and fecundity, to substitute 

 itself for them, to take possession of our beds, and destroy 

 our pares for reproduction. This anticipation has, happily, 

 not been realised ; and our oysters, whether the gravette of 



