34 SHELLFISH CONTAMINATION FROM SEWAGE-POLLUTED WATERS. 



ined, and some proved to be satisfactory, while others were unfit for 

 such purposes. The bacteriological condition of water can only be 

 determined by making the necessary examinations. Most large 

 cities have records of the bacterial content of their water supply, and 

 if such waters were being used for washing shellfish the oystermen 

 could inform themselves as to its purity from the records of the city 

 health office. 



That the liquor bathing the meat of the oyster contains more 

 bacteria per given volume than does an equal volume of minced 

 oyster meat is shown in Tables 10 and 11. A brief, brisk washing, 

 not to exceed 3 or 5 minutes in duration, is usually sufficient to 

 remove this liquor, and also the adhering sand and grit which may 

 be clinging to the gills of the oyster. It is not necessary to soak 

 oysters over night in order to wash them. Soaked oysters, like 

 floated oysters, deteriorate more rapidly than do those which have 

 not been so treated. Oysters may be washed two or three times 

 before finally reaching the consumer. The total length of all the 

 combined washings should not exceed 30 minutes, and pure iced 

 water should be used. The efficiency of any washing device or 

 method depends largely on its mechanical points, and the amount 

 of soakage taking place will vary with the manner of washing, the 

 relative quantity of oysters and water used, and the temperature 

 of the wash water. 



Tables 10 and 11 illustrate the relative bacterial content of the meat 

 and liquor of shellfish, Table 1 1 being considered with special refer- 

 ence to the development in plain and in saltless agar. 



TABLE 10. Bacterial content of oyster meat and oyster liquor compared. 



The results show that the oyster liquor in these samples contained 

 more than seven times as many organisms per given volume as did 



