EXPERIMENTAL STUDY OF THE OYSTER GILL 



26 



The oyster was immobilized b}' plaring it on a brick and embedding its left shell 

 in a mixture made of 1 part of cement and 3 parts of plaster of Paris. A glass rod, 

 attached bj' means of the same mixture to the right valve of the oyster, was connected 

 to the lever of a recording apparatus (fig. 9) and the oyster was kept in a large aquav 



•/•iitv ■rut --:!■ r 



Fig. 9.— Method employed to study the shell movements of oysters, o.— oyster immobilized in plaster 

 r.— rubber connections; «.— glass rods attached to the levers 0) of the recording apparatus; /,- 

 time recorder; to.— weight 



of Paris; 

 -Foxboro 



rium tank with running sea water. The records of the movement of the shells were 

 made with a Foxboro or Bristol two-pen time recorder. The weight of the cement, 

 glass rod, and lever was counterbalanced in such a way that the shell bore no addi- 

 tional pressure. (Fig. 9.) In all the experiments the records of two oysters were 

 taken simultaneously and the temperature of the water was recorded on the thernio- 



