THE OYSTER. 77 



part of the bottom that no one would have much 

 chance of finding oysters by promiscuous dredging, in 

 ignorance of their location. Although the young are 

 distributed every year by the tides and currents over 

 all parts of the bottom, the dredge seldom brings up 

 even a single oyster outside the limits of the beds, 

 under natural conditions. 



The restriction of the oysters to certain points does 

 not depend on the supply of food, for this is every- 

 where abundant, nor to any great degree upon the 

 character of the water. It is almost entirely due to the 

 nature of the bottom. 



The full-grown oyster is able to live and flourish in 

 soft mud so long as it is not buried too deeply for the 

 open edge of the shell to reach above the mud and 

 draw a constant supply of water to its gills; but the 

 oyster embryo would be ingulfed and smothered at 

 once if it were to fall on such a bottom, and in order 

 to have the least chance of survival it must find some 

 solid substance upon which to fasten itself, to preserve 

 it from sinking in the soft mud, or from being buried 

 under it as it shifts with wind and tide. In the de- 

 posits which form the soft bottom of sounds and 

 estuaries golid bodies of any sort rarely occur, and the 

 so-called *' rocks " of the Chesapeake are not ledges or 

 reefs, but accumulations of oyster shells. 



Examination of a Coast Survey chart of any part of 

 the Chesapeake Bay or of any of its tributaries will 

 show that there is usually a mid-channel, or line of 

 deep water, where the bottom is generally soft and 

 where no oysters are met with, and on each side of 

 this an area where the bottom is hard, running from 



