110 OYSTERS, AND ALL ABOUT THEM. 



by a long series of developmental changes which take place 

 in that ovum after it has united with another living particle 

 of extremely minute size, the spermatozoon, and in conse- 

 quence of the fertilisation effected by that union, just as 

 the ovule of a plant develops in consequence of the influ- 

 ence of the pollen upon it. And the first problem is, 

 Where are these ova and spermatozoa formed ? Does each 

 oyster produce both, or are they formed in distinct oysters ? 

 (i) This is, in fact, the vexed question of the sexes of the 

 oyster, which has been the subject of so much discussion, 

 and for which the answer is gradually shaping itself, 

 thanks mainly to the recent labours of Mobius and Hoek. 



I have already stated that if the surface of the trunk 

 of a full-grown oyster is examined carefully with a lens, or 



(/) In order to shew the difference of opinion upon this point of 

 the Oyster Question, I quote an extract from an article headed 

 " Oysters : Native and Foreign," by an anonymous writer in " Whit- 

 aker's Journal of Amusing and Instructive Literature," (1876.) 



" Staid, morose, and uncommunicative as an oyster is, closely 

 secured in his shell armour, the thousand years or more that he has 

 been under cultivation have not served to unfold half the secrets 

 connected with his internal economy and domestic arrangements. To 

 this day, the mode of reproduction in this creature is not definitely 

 ascertained, and it is generally believed that it is ' hermaphrodite,' i.e., 

 that each individual possesses the attributes of both sexes. To this 

 view, the writer is personally opposed ; it is more probable that a 

 similar course prevails with these molluscs to that which is known to 

 obtain among fish. The milt of the male salmon, for instance, and the 

 ova of the female are both emitted at the same time, and the latter 

 fecundated by coming into contact, in the water, with the former. 

 Oysters, however, are not oviparous, but viviparous, and the young are 

 emitted from the mother oyster in a perfect state ; it is more than 

 probable that impregnation takes place through the agency of milt 

 floating in the water, the structure of the oyster preventing the possi- 

 bility of any other solution of the difficulty." 



