ABOUT THE SPAWN. 247 



spawning-season. Each adult individual sheds its own 

 cloud of progeny. A living dust is, as it were, exhaled 

 from the crowded oyster-bank, disturbing the water, and 

 communicating to it a dense foggy appearance ; and this 

 dust gradually spreads abroad, until it is scattered far 

 away from its focus of production. Unless the " spat," 

 as the spawn is technically called, encounters some solid 

 body to which it can adhere, it inevitably falls a victim 

 to the voracity of the numerous enemies which prey upon 

 it. The state of the weather is also an important con- 

 sideration, as a cold day will kill the spat. 



The quantity of spawn produced by a single oyster is 

 not very accurately known. Some authorities count by 

 millions ; others estimate the season's product at five or 

 six hundred thousand. Mr. Bertram says that he has 

 examined oyster-spawn, taken direct from the oyster, 

 under a powerful microscope ; he describes it as a liquid 

 of some little consistency, in w^hich the young oysters, 

 like the points of a hair, sw r im actively about, in great 

 numbers, as many as a thousand being distinguishable in 

 a very minute globule of spat. There can be no doubt, 

 therefore, of the fecundity of this wonderful hermaphrodite, 

 but it is much modified by variations of temperature. If 

 the breeding-season be not mild and genial, the fall of 

 spat is only partial. 



On finally taking leave of the parent 

 shell, the young oyster is provided with 

 a locomotive apparatus ; a kind of pad 

 or cushion, surrounded by vibratory 



. YOUNG OYSTER. 



cilise, and set in motion by certain 



powerful muscles. Hence it is able to swim about freely 



in search of a resting-place and this once found, a 



