I068 OYSTERS, AND ALL ABOUT THEM. 



basis for attachment. . . . but there is still another 

 reason. As the flood-tide rushes up the channels, it stirs 

 up the fine mud which has been deposited in the deep 

 water. The mud is swept up on to the shallows along the 

 shore, and if these are level much of the sediment settles 

 there. If, however, the flat is covered by groups of 

 oysters, the ebbing tide does not flow off in an even sheet, 

 but is broken up into thousands of small channels, through 

 which the sediment flows down to be swept out to sea. 

 The oyster bed thus tends to keep itself clean, and for 

 these various reasons it follows that the more firmly estab- 

 lished an oyster bed is the better is its chance of perpetua- 

 tion, since the young spat finds more favourable conditions 

 where there are oysters, or at least shells, already, than it 

 finds anywhere else. 



Now what is the practical importance of this descrip- 

 tion of a natural bed ? It is this : Since a natural bed 

 tends to remain permanent, because of the presence of 

 oyster shells, the shelling of bottoms where there are no 

 oysters furnishes us with a means of establishing new beds 

 or of increasing the area of the old ones. (z) 



The oyster dredgers state, with perfect truth, that by 

 breaking up the crowded clusters of oysters and by scatter- 

 ing the shells, the use of the dredge tends to enlarge the 

 oyster beds. The sketch just given shows the truth of this 

 claim, but this is a very rough and crude way of accom- 

 plishing this end, and I shall devote the rest of this chapter 

 to a description of the means which have been employed, 

 in different places, to accomplish the same result more 

 efficiently and methodically. 



Although the development of the oyster industry on a 

 large scale is quite modern, seed oysters for planting have 

 (i) The Development and Protection of the Oyster in Maryland. 



