338 OYSTER-GROWTH. [CHAP. vin. 



The operation of nursing, brewing, and exuding the spat 

 from the parental shell will occupy a considerable period- 

 say from two to four weeks. It is quite certain that the 

 close-time for oysters is necessary and advantageous, for we 

 seldom find this mollusc, as we do the herring and other 

 fish, full of eggs, so that most of the operations connected 

 with its reproduction go on in the months during which there 

 is no dredging. As I have indicated, immense quantities of 

 the spawn of oysters are annually devoured by other mol- 

 luscs, and by fish and crustaceans of various sizes ; it is 

 well, therefore, that it is so bountifully supplied. On occa- 

 sions of visiting the beds I have seen the dredge covered 

 with this spawn ; and no pen could number the thousands 

 of millions of oysters thus prevented from ripening into life. 

 Economists ought to note this fact with respect to fish gener- 

 ally, for the enormous destruction of spawn of all kinds must 

 exercise a very serious influence on our fish supplies. I may 

 also note that the state of the weather has a serious in- 

 fluence on the spawn and on the adult oyster-power of spawn- 

 ing. A cold season is very unfavourable, and a decidedly 

 cold day will kill the spat. 



Some people have asserted that the oyster can reproduce 

 its kind in twenty weeks, and that in 

 ten months it is full-grown. Both of 

 these assertions are pure nonsense. At 

 the age of three months an oyster is 

 not much bigger than a pea; and the 

 age at which reproduction begins has never been accurately 

 ascertained, but it is thought to be 

 three years. I give here one or 

 two illustrations of oyster-growth in 

 order to show the ratio of increase. 

 The smallest, about the dimensions 

 of a pin's head, may be called a fortnight old. The next 



