=Oysters Preserved in Shell.=--So long as the oyster retains its natural juices, it will live out of water, provided the changes in the temperature are not too sudden. The moment the oyster opens its shells, however, the juices run out, and in a short time afterward the oyster dies. To prevent the oyster opening its stony overcoat, is the object of oyster-shippers; and the Patent Office bears witness to their many devices having this object in view. Some wire the shells, others clasp or envelope the broad end of the shells with tin or other metal. No doubt these devices aid in keeping the oyster alive and fresh a little longer. Whether the nervous system of the oyster is affected by the process, is a question. Scientists tell us that oysters possess organs of sensation, and all who have handled oysters learn in time that a sudden jar or shock will kill them. The jar of the machinery of a steamboat will sometimes kill an oyster. When shipped to Europe they are ordered to be stored as far away from the machinery as possible. Some authorities claim that the oyster can hear. One cannot noisily approach an oyster-bed at feeding time without their hearing, and instantly every shell is closed. A cloud or a boat passing over an oyster-bank will cause every shell to close with proverbial tightness, and the sound of thunder will often kill them while they are in transit,--conclusive evidence that the nervous system in an oyster, while not highly developed, is of sufficient importance to merit attention from those who roughly handle oysters.
=The Food of the Oyster= consists of minute animal and vegetable organisms and small particles of organized matter. Ordinary sea-water contains an abundance of this sort of food, which is drawn into the gills with the water. As the water strains through the pores into the water tubes, the food particles are caught on the surface of the gills by a layer of adhesive slime. As soon as they are entangled, the microscopic hair-like projections on the gills strike against them in such a way as to slide them along the gills toward the mouth. When they reach the anterior ends of the gills, they are pushed off, and fall between the lips, which are also covered with thin hair-like projections, which carry the particles forward until they slide into the mouth. No wonder the intelligent tramp wished that he might become an oyster. His food would then come to him in a sort of endless progression.