The North Carolina Field 233 



erations of oysters attach to the upper ones, so that 

 finally the living oysters are raised first to the low and 

 then nearly to the high tide line. In this manner, the 

 point, advancing on the foundation that it itself prepares, 

 thrusts itself in the form of a narrow reef out into the 

 current, and its advance will continue until the direction 

 of the current is changed, or its force is checked. 



In the meantime, the current has become so slow at the 

 point on the shore from which the reef began to grow, 

 that most of the oysters in that locality have died. 

 There is here, then, no longer a living crust of oysters 

 on the reef to protect it from erosion, and gradually the 

 rising and falling tides wear through it, and cut it down 

 until the remainder of the reef has lost all connection 

 with the shore from which it arose, and has become an 

 island. This widens somewhat, waves now and then 

 throw detached oysters on to its center, floating matter 

 catches there, grass begins to grow, and it gradually rises 

 above the ordinary high tide line. Around its margins 

 oysters still continue to grow between the tide lines. 



Such a process requires many years for its completion, 

 and even after an island is formed, it probably is still sub- 

 jected to slow but unceasing changes that are in some 

 cases constructive, in others destructive. In many of the 

 bays or rivers, all stages of growth, from the small and 

 inconspicuous point to the fully developed island, may 

 be observed. 



To one familiar with other fields where oysters never 

 are found fixed between the tide lines, but exist only on 

 bottoms that are continually immersed, these peculiarly 

 elevated reefs, and bottoms so generally barren, are very 

 curious. Two questions at once arise in his mind. 

 First, why do not oysters naturally establish themselves 



