86 THE OYSTER. 



to the open end of number one, thus raising itself a 

 little above the crowd. After number one was killed 

 number two continued to grow, and number three 

 fastened itself to its shell, and so on. Usually the 

 oysters upon such a bed are small, but in some places 

 shells twelve or fourteen inches long are met with. 

 The most significant characteristic of a bed of this kind 

 is the sharpness of its boundaries. In regions where 

 the oysters are never disturbed by man it is not unusual 

 to find a hard bottom, which extends along the edge of 

 the shore for miles, and is divided up into a number of 

 oyster rocks, where the oysters are so thick that most 

 of them are crowded out and die long before they are 

 full-grown, and between these beds are areas where 

 not a single oyster can be found. The intervening area 

 is perfectly adapted for the oyster, and when a few 

 bushels of shells are scattered upon it they are soon 

 covered with young, and in a year or two a new oys- 

 ter rock is established upon them, but when they are 

 left to themselves the rocks remain sharply defined. 

 What is the reason for this sharp limitation of a 

 natural bed? Those who know the oyster only in its 

 adult condition may believe that it is due to the ab- 

 sence of power of locomotion, and they may hold that 

 the young oysters grew up among the old ones, just as 

 young oak trees grow up where the acorns fall from 

 the branches. This cannot be the true explanation, 

 for the young oysters are swimming animals, and they 

 are discharged into the water in countless numbers, to 

 be swept away to great distances by the currents. As 



