OYSTERS 133 



single ripe oyster. About a fortnight after the eggs have 

 been shed, the same tubular chambers in the oyster's body 

 which produced the eggs by growth from their inner walls, 

 produce the spermatozoa, so that they are too late to 

 fertilise the eggs of the same oyster. They pass out of 

 the oyster into the sea water, and are carried within the 



FIG. 31. The eggs of the oyster taken from 

 a ripe individual magnified 500 times 

 linear. 



shelter of the shells, and so on to the surface of the 

 protected bodies of other neighbouring oysters by 

 the currents created by the " ciliated " gill-plates of these 

 neighbours. 



The sperm particles or spermatozoa (Fig. 32) are 

 produced by millions, and form a cloud finer than dust 

 in the sea water. They are carried within the shells of 

 both egg-producing and sperm-producing oysters, and are 



