32 THE POPULAR SCIENCE MONTHLY. 



of the sound is shoal, and these shoals covered with oysters scattered 

 singly and in small groups, or existing in large, well-defined beds. 

 Several small creeks empty their waters into this sound, and one large 

 river, the Pocomoke, discharges into it also. The majority of the 

 beds were found on the eastern side of the sound, and the largest 

 were about the middle and near the mouths of the creeks.^ The beds 

 in both sounds were located and defined during the summer of 1878, 

 and the area upon which oysters were scattered was also ascertained 

 approximately. The entire area in both sounds upon which oysters 

 were found amounts to fifty-four square miles. The area covered 

 by oysters, but only very thinly, they being scattered in small 

 groups or singly, comprises in Tangier Sound fourteen square miles, 

 and in Pocomoke Sound twenty-nine square miles. The area of the 

 beds proper, or those grounds where the oysters are to a great extent 

 uniformly spread and where the majority of the dredging-vessels work, 

 amounts to six square miles in Tangier Sound and to four square miles 

 in Pocomoke Sound. 



The information obtained in 1878, so far as it related to the con- 

 dition of the beds, may be summarized as follows : The number of 

 oysters on the beds had been very much diminished since the com- 

 mencement of the fishery, or during the last thirty years. The area 

 of the beds had been greatly increased since the commencement of 

 the fishery. There had been during the period alluded to no change 

 of the usual natural conditions to which the animals are subjected. 



Before attempting to draw any conclusions from the above, it will 

 be well to see if the extension in area of the beds and diminution of 

 the number of oysters can be accounted for by the action of natural, 

 unassisted causes. 



After the original formation and growth of the beds, they would 

 at some time, the same conditions continuing to operate, cease their 

 development, neither increasing in size nor in number of oysters, there 

 being a natural limit to expansion in either direction. Suppose, then, 

 a bed to have extended itself as far as the conditions of bottom and 

 water or other natural limit would allow, all future expansion could be 

 only in the number of oysters on the bed, and this is limited by the 

 amount of food and room for development, the question of enemies 

 not being considered, as, there being no increase, if they were not in 

 sufficient numbers to prevent the growth of the bed and number of 

 oysters, they would not be sufficient to cause its destruction or deteri- 

 oration. The number of oysters on a limited bed would then steadily 

 increase, as long as there were sufficient room and food supplied them, 

 until they had reached their limit, a rather undefinable one, in that 

 direction. Having reached that point, the number of oysters would 

 to all intents remain the same as long as the conditions under which 

 they had previously lived were not changed. To cause, then, either 

 an increase or diminution of the number of oysters or the size of the 



