22 THE OYSTER AND THE OYSTEK IXDUSTIIY. 



own weight and under the force of tlie waves. On hard ])ottom the 

 disintegrated i)arts are rolled a])out and more or less evenly distrib- 

 uted, resulting eventually in the production of other similar clusters 

 scattered at intervals. On soft mud the shells can not roll so readily, 

 and they fall and remain close to the base of the original cluster, 

 where, if not completely engulfed, they form places of attachment for 

 new generations. If the mud be very soft they sink for a short dis- 

 tance and accumulate until they harden the bottom and form a firm 

 support for the shells which fall later, and which in turn are covered 

 with a growth of young. 



As these phenomena recur year after year the original single cluster 

 gradually extends around its edges now more or less at the top until 

 it becomes converted into a little bed composed of a dense mass of 

 clusters, with its boundaries sharply defined and limited by the soft 

 mud surrounding it. A number of other clusters have probably been 

 gro'svdng simultaneously on the same muddy bottom, and, the areas 

 between becoming narrowed and ol)literated, there results a great 

 flat bed made up of a number of smaller patches separated by a 

 muddy network. Where a deep, muddy channel occurs the oyster 

 growth usually stops near the edge of the slope, the shells which would 

 else serve as clutch sinking down into the deep soft ooze. Opposite 

 the mouths of smaller streams, even where there is no such deep chan- 

 nel, the oyster growth is also inhibited, partly by the freshness of tlie 

 water, but principally and often entirely by the deposit of silt which 

 soon spreads its thin coating over everything lying on the bottom. 

 In some cases the beds may be completely interrupted, but in others 

 they are continuous in their offshore part, passing by and inclosing 

 the unfavorable area as an oval or subtriangular barren, muddy patch 

 surrounded, excepting on its shoreward side, by productive oyster 

 bottom. 



It is difficult to say what may have been the condition of the nat- 

 ural beds in Chesapeake Bay before they were disturbed by man, but 

 at the present time they are essentially in the condition so far de- 

 scribed, though wdth their boundaries of ten ill-defined and the clusters 

 usually smaller and less dense as a result of tonging and dredging. 

 They usually exhibit no great depth of shells, though the bottom is 

 more or less hardened by their accumulation in the undei-lying mud. 

 They usually extend alongshore, their greatest length in the direction 

 of the currents and their width extending from a couple of feet below 

 low water toward, and often to, the edge of the deep, muddy 

 channels. 



In South Carolina and adjacent regions the beds are of essentially 

 the same type, excepting that they are smaller and narrower, and 

 particularly that they are crowded closer to the shores and almost 

 entirely confined to the area between high and low water, a situation 

 impossible in Chesapeake Bay and more northern regions, owing to 

 the killing cold of winter. 



Further development in the history of natural oyster beds beyond 

 the stage which has been described results in a gradual thi(>kcning of 

 the deposit of shells and the production of a short reef or lump, with 

 a more or less distinct shoaling of water over its top. The living 

 oysters standing vertically in the dense mass, with their growing tips 

 directed upward and kept clean by the currents, present the only 

 available place for spat fixation. Each year the set occurs on preced- 



