236 REPOKT OF THE COMMISSIONER OF FISHERIES. 



The waters of Mount Hope Bay, at least in the areas occupied ])y 

 oyster ground, are also free from sewage pollution of any extent. 



The Warren River, however, from the town of Warren to its union 

 with the Providence River, must be considered a polluted stream. 



Examination of oysters and other shelltish from various portions 

 of the river and ba}" show that there is a distinct relation between the 

 presence of B. coll in the water and in the shelltish living in these 

 waters. When B. coll is entirely absent from the water it can not be 

 found in the shelltish, ])ut when the surrounding waters are infected 

 with it it is almost certain to be found in the shelltish. It seems 

 probable, however, that B. coll may be present in larger numbers in 

 the water than in oysters, for almost without exception a much larger 

 numl)er of water samples than oysters from a given locality gav^e posi- 

 tive reactions for sewage bacteria. This fact ma}' be explained as due 

 partly to the influence of the tide currents and partly to the resist- 

 ance against infection exerted by the oyster itself. 



Examination of the shelltish from the lower river and bay demon- 

 strate that the bacteria usuall}' occurring in oysters taken from uncon- 

 taminated waters are such forms as are commonly found in water. 

 No organisms of the colon group were isolated from these 03'sters. 

 Hence, analj'sis of the juice contained within the shells of 03'sters, 

 clams, and mussels is practically an analysis of the water in which 

 these molluscs are living. The stomachs of 03'sters are often found 

 sterile. B. coll has been found in the juice of o}'sters whose intes- 

 tines were apparentlj' free from infection.* 



No organism which will grow in the presence of 0.05 per cent of 

 phenol has been found in oysters from an unpolluted source. 



The results obtained in these experiments indicate that B. coll is 

 not normall}^ found in sea water or in the common edible shelltish, 

 and that the presence of this organism in oysters, clams, mussels, and 

 similar shelltish is an indication of sewage pollution. 



BIBLIOGRAPHY. 



Cameron, Sir Charles. On Sewage in Oysters. British Medical Journal, 1880, vol. 

 II, p. 471. 



Klein, E. Oysters and Typhoid. Twenty-fourth Annual Report of the Local Gov- 

 ernment Board, 1894-95. 



BuLSTRODE, H. T. Oyster Culture in Relation to Disease. Twenty-fourth Annual 

 Report Local Government Board, 1894-95. 



Conn, H. W. Oyster Epidemic of Typhoid Fever at Wesleyan University. Med- 

 ical Record, 1894, vol. 46, p. 743. 



FooTE, C. J. A Bacteriological Study of Oysters with Special Reference to them as a 

 Source of Typhoid Infection. Medical News, 1895, vol. 66, p. 320. 



Johnston-Lavis, H. J. The Possible Conveyance of certain water-borne Diseases, 

 especially Typhoid Fever, by Oysters and other Molluscs. British Medical Jour- 

 nal, 1895, vol. I, p. 559. 



De GiAXA. Oysters and Typhoid. British Medical Journal, 1895, vol. i, p. 390. 



