EXPERIMENTAL STUDY OF THE OYSTER GILL St 



of the Shellfish Industry (1925) failed to recommend any precise bacterial standards 

 for waters from which the talcing of shellfish is permitted until additional data are 

 assembled and considered. It was regarded as unnecessary, however, to apply to 

 such waters the rigid standards that are established for drinking-water supplies in 

 interstate commerce. It is known at present that because of the mode of feeding, 

 the oyster is able to concentrate in the shell liquor the microorganisms present in the 

 sea water. Undoubtedly the process is dependent on the rate of filtration of water 

 through the gills and on the rate of ejection of the accumulated material. Both 

 processes very likely are affected by changes in the environment. Wells (1926), 

 working at the United States Public Health Laboratory at Fishermans Island, 

 arrived at the conclusion that the number of B. coli in the shell liquor is higher as 

 compared to that of the water, where the B. coli concentration was low, and that the 

 ratio decreased as the abundance of B. coli in the water increased. The same relation 

 was observed by Tarbett (1926) in the waters of lower Chesapeake Bay. He has 

 shown that with water scoring from to 0.5, the ratio of water score to oyster score 

 was 1 to 600; in water scoring 1.4 to 5 the ratio was 1 to 44.8; and in water scoring 

 from 14 to 50 the ratio was 1 to 7.6. Tarbett admits that the relation between the 

 B. coli content in water and in the oyster is not a simple one and that temperature 

 is an important factor. Neither Wells nor Tarbett give any explanation for the 

 differences in the ratios they have observed. It is very likely that a number of 

 factors, like temperature, pH, and changes in the chemical composition of water, 

 should be held responsible for the differences in the ratios observed by these investi- 

 gators. It is difficult to believe that merely the fluctuation in the abundance of 

 B. coli may affect the activity of the oyster. It is very likely that the increase or 

 decrease in B. coli content in shallow and polluted waters where the observations were 

 carried out are accompanied by physical and chemical changes in the water, which 

 in turn affect the activity of the oyster gills. 



In a study of seasonal fluctuations in B. coli score in the oyster, and in discussing 

 the questions of feeding and hibernation, some of the investigators (Round, 1914; 

 Nelson, 1921, 1923) regarded the oyster as feeding whenever its shells are open'. As 

 it will be shown in the present paper, the fact that the shells are open does not neces- 

 sarily mean that the oyster is feeding. The two phenomena namely, the contrac- 

 tion of the adductor muscle and the ciliary activity of the gill epithelium — are 

 independent from one another and should be studied separately. 



The crisis of the oyster industry in 1924 caused a revision of the methods of 

 sanitary control of shellfish. At the same time, the question of the effect of temper- 

 ature on the activity of the oyster was taken up again by the bacteriologists engaged 

 in the sanitary inspection of shellfish and by the oyster growers interested in the 

 safety of their product. It is the author's belief that the solution of the practical 

 problem concerning the standard of purity of the oyster should be based on a profound 

 knowledge of the functions of the organism and its relation to its environment. On 

 the other hand, understanding of the activity of the organism is essential for the 

 oyster growers who, by adopting methods that permit self-purification of the oj'ster, 

 are trying to insure the cleanliness of their product. *" 



The present investigation was made for the purpose of filling the gap in our 

 knowledge of the physiology of the oyster and to supply information concerning the 



