CHAPTER II. 



THE ANATOMY OF THE OYSTER. 



The most prominent fact in the organization of the 

 oyster is its shell. Its body is shut in between two 

 long concave stony doors, which are made of lime- 

 stone, and are fastened together at one end, somewhat 

 in the same way that the covers of a long, narrow 

 check-book are bound together at the back. One of 

 these shells, the flat one, is on the right side of the 

 body, and the other, which is much deeper, on the 

 left. When oysters are fastened to each other or to 

 rocks, the left shell is attached, and the oyster lies on 

 its left side. When it is at home and undisturbed its 

 shell is open, so that the water circulates within it, but 

 when disturbed it shuts its shell with a snap, arid is 

 able to keep it firmly closed for a long time. The 

 snapping drives out the water, together with any irri- 

 tating substances which may find their way in, and on 

 the natural beds the oysters snap their shells shut, 

 from time to time, for this purpose. The snapping is 

 popularly called feeding, but it is nothing of the kind. 

 It serves to drive food out instead of taking it in, and 

 so long as the shell is open a gentle current of water is 

 drawn in by a delicate piece of microscopic machinery 



