WHEN DO OYSTERS BECOME EEPEODUCTIVE ? 235 



and the age at which reproduction begins has never been accu- 

 rately 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 ^.^am-, 



increase. The smallest, about the ^ i'C?^'^ 



dimensions of a pin's head, may be jIHfiL nJ^-^v 

 called a fortnight old. The next size 

 represents the oyster as it appears 

 when three months old. The other 

 sizes are drawn at the ages of five, eight, and twelve months 

 respectively. Oysters are usually 

 four years old before they are sent 

 to the London market. At the age 

 of five years the oyster is, I think, 

 in its prime ; and some of our most 

 intelligent fishermen think its aver- 

 age duration of life to be ten years.' 



In these days of oyster-farming the time at which the 

 oyster becomes reproductive may be easUy 

 fixed, and it will no doubt be found to 

 vary in difierent localities. At some places 

 it becomes saleable — chiefly, however, for 

 fattening— in the course of two years ; at 

 other places it is three or four years before 

 it becomes a saleable commodity ; but on 

 the average it will be quite safe to assume 

 that at four years the oyster is both ripe 

 for sale and able for the reproduction of 

 its kind. Let us hope that the breeders will take care to 

 have at least one brood from each batch before they ofier any 

 for sale. Oyster-farmers should keep before them the folly of 

 the salmon-fishers, who kill their grilse — i.e. the virgin fish — 

 before they have an opportunity of perpetuating their race. 



Another point on which naturalists differ is as to the 

 quantity of spawn from each oyster Some enumerate the young 

 by thousands, others by millions. It is certain enough that the 

 number of young is prodigious — so great, in fact, as to prevent 

 their all being contained in the parent shell at one time ; but I 

 do not believe that an oyster yields its young " in mUlions " — 

 perhaps half a million is on the average the amount of spat 

 which each oyster can " brew " in one season. I have examiaed 

 oyster-spawn (taken direct from the oyster) by means of a 



