CHAP. VHI. J THE SPAWNING OF OYSTERS. 337 



season, because were the beds disturbed by a search for the 

 healthy oysters the spawn would be scattered and destroyed. 



Oysters do not leave their ova, like many other marine 

 creatures, but incubate them in the folds of their mantle, and 

 among the laminse of their lungs. There the ova remain 

 surrounded by mucous matter, which is necessary to their 

 development, and within which they pass through the embryo 

 state. The mass of ova, or " spat " as it is familiarly called, 

 undergoes various changes in its colour, meanwhile losing its 

 fluidity. This state indicates the near termination of the 

 development and the sending forth of the embryo to an 

 independent existence, for by this time the young oysters can 

 live without the protection of the maternal organs. An eminent 

 French pisciculturist says that the animated matter escaping 

 from the adults on breeding-banks is like a thick mist being 

 dispersed by the winds the spat is so scattered by the waves 

 that only an imperceptible portion remains near the parent 

 stock. All the rest is dissipated over the sea space ; and if 

 these myriads of animalculse, tossed by the waves, do not meet 

 with solid bodies to which they can attach themselves, their de- 

 struction is certain, for if they do not fall victims to the larger 

 animals which prey upon them, they are unfortunate in not fix- 

 ing upon the proper place for their thorough development. 



Thus we see that the spawn of the oyster is well matured 

 before it leaves the protection of the parental shell ; and by 

 the aid of the microscope the young animal can be seen with 

 its shell perfect and its holding-on apparatus, which is also a 

 kind of swimming-pad, ready to clutch the first " coigne of 

 vantage" that the current may carry it against. My theory 

 is, that the parent oyster goes on brewing its spawn for some 

 time I have seen it oozing from the same animal for some 

 days and it is supposed that the spawn swims about with 

 the current for a short period before it falls, being in the 

 meantime devoured by countless sea animals of all kinds. 



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