THE OYSTER. 87 



they are too small to be seen at this time without a 

 microscope, it is impossible to trace their wanderings 

 directly, but it is possible to show indirectly that they 

 are carried to great distances, and that the water for 

 miles around the natural bed is full of them. They 

 serve as food for other marine animals, and when the 

 contents of the stomachs of these animals are carefully 

 examined with a microscope, the shells of the little 

 oysters are often found in abundance. While examin- 

 ing the contents of the stomach of Lingula in this way 

 I have found hundreds of the shells of the young oys- 

 ters in the swimming stage of growth, although the 

 specimens of Lingula were captured several miles from 

 the nearest oyster-bed. As Lingula is a fixed animal, 

 the oysters must have been brought to the spot where 

 the specimens were found, and as Lingula has no means 

 of capturing its food, and subsists upon what is swept 

 within its reach by the water, the presence of so many 

 inside its stomach shows that the water must have con- 

 tained great numbers of them. 



It is clear, then, that the sharp limitation of the area 

 of a natural oyster-bed is not due to the absence in the 

 young of the power to reach distant points. There 

 is another proof of this, which is familiar to all oyster- 

 men the possibility of establishing new beds without 

 transplanting any oysters. 



I once observed an illustration of this. On part of 

 a large mud-flat which was bare at low tide there 

 were no oysters, although there was a natural bed 

 upon the same flats, about half a mile away. 



