SOURCES OF CONTAMINATION. 



25 



the quotations from the literature on this subject (page 40), many of 

 the known epidemics of typhoid fever due to eating infected shellfish 

 were traceable to those which had become polluted during the process 

 of drinking. There appears to be no necessit}^ for floating oysters, 

 and, as practiced at present, it is often exceedingly dangerous to 

 public health. 



The Xew York City Health Department Report on Typhoid Fever" 

 shows many illustrations of floats located in waters subject to sources 

 of pollution and the conclusion reached is as follows: "The process 

 of 'freshening,' 'fattening/ or 'drinking/ often performed as it is in 

 small streams, badly contaminated with sewage, is a most dangerous 

 practice and should be discontinued. '' The following data on floated 

 and unfloated oysters confirm these views: 



TABLE 7. Bacteriological examination of condemned shellfish token from floats located 



in polluted waters. 



COMPOSITE SAMPLES OF FIVE OYSTERS KACII. 



WATER IN REGION OF FLOATS. 



These results show that all the samples of shellfish and water taken 

 from this locality were contaminated. In this case the water con- 

 tained sufficient salt for the normal growth of oysters, but it was 

 badly polluted. 



TABLE 8. Bacteriological results on unfloated and floated oysters and on water over floats. 



OYSTERS. 



72743 Hull. 



