312 ANIMAL SKETCHES. CHAP. xxi. 



Sweden which forms a natural hothouse for oyster-culture 

 oysters are found to contain ripe spat as early as the 

 end of March. The spatting season may continue until 

 the end of September. And one of the most curious facts 

 in the natural history of the oyster is this : that so soon as 

 she has laid her eggs the mother-oyster changes her sex 

 and becomes a male. Not all oysters, however, are so 

 changeable as this. Americans and Portuguese have not 

 learned the trick or have abandoned it for the more staid 

 and more respectable habits. Whether this change of sex 

 in our oyster takes place several times in a season, and if 

 so, how often, is not known. It is a curious arrangement : 

 but depend upon it, it has not been instituted by Nature 

 without a purpose. 



THE END. 



RICHARD OLAV AND SONS, I1MITED, LONDON AND BtJNGAV 



