SOURCES OF CONTAMINATION. 19 



These samples of water were collected with difficulty from the 

 right lower deck, aft, on a steamboat while the wind was blowing a 

 gale and the sea was greatly agitated. They were taken in 4-ounce 

 sterile bottles hung at the end of a weighted line. At the upper 

 limit at which oysters grew to maturity the water had a saline con- 

 tent of from 0.97 to 1.08 per cent. Seed is said to set above this 

 point, but it does not mature well. 



COMPARISON OF RESULTS OBTAINED ON SAMPLES FROM KNOWN SANITARY AND 

 INSANITARY GROUNDS. 



The New York City Board of Health 52 has demonstrated that the 

 beds from which oysters are taken for consumption in that city often 

 lie in grossly polluted waters. It is not the depredations of the star- 

 fish, borers, drumfish, etc., that threaten the life of the shellfish 

 industry, but the contamination by wastes. These practical facts 

 should stimulate every oysterman to see that his grounds are in a fit 

 sanitary condition and that they are kept fully protected from sub- 

 sequent contamination. Oystermen should not deceive themselves 

 by believing that their grounds are free from pollution, in the absence 

 of definite evidence to the contrary. If oyster growers can not 

 themselves determine the sanitary conditions of their layings, they 

 should appeal to their National organizations, or enlist the aid 

 and cooperation of their State shellfish commissions and boards 

 of health. A thorough sanitary survey of every oyster bed should 

 be made, and this should be supplemented by repeated bacteriological 

 examinations of both the water and shell stock taken at regular inter- 

 vals under varying conditions. 



There are many factors which may influence the degree and extent 

 of sea-water pollution, and before passing judgment on the sanitary 

 condition of a particular oyster laying all the facts in the case should 

 be considered. The influence of tidal change, percentage of sunlight, 

 amount of rainfall, seasonal variations, prevailing winds and currents, 

 the depth, and the amount of salt in the water must all be consid- 

 ered, though of course the proximity to sources of possible contami- 

 nation is the most important item. Oysters offered for sale from 

 polluted beds are in constant danger of seizure and condemnation 

 by health officials. The occurrence of sewage matter in oysters can 

 not be tolerated from a public health point of view. 



Where oyster beds are proved to be polluted or located in ques- 

 tionable territory, and it is desired to continue their use, there would 

 seem to be no objection to raising seed stock on such grounds for 

 transplanting purposes only. Oysters grown on such holdings 

 should under no circumstances be offered for sale to be consumed 

 either raw or cooked. Numerous experiments and the opinion of 

 practical oystermen indicate that oysters taken from polluted beds 

 "cleanse" themselves in a few days when placed in pure sea water. 



