74 BACTERIOLOGY OF THE OYSTER. 



From the table it is seen that at the beginning of the experiment 

 there were on the average forty-six B. coh per cubic centimeter of 

 oyster juice. After a period of four days this number had dropped to 

 an average of 7.3 per cubic centimeter and after a period of nine days 

 the number had still further decreased so that there were on the average 

 only 2.8 B. coli per c.c. of the oyster juice. This shows that under the 

 conditions of the experiment, oysters which contained 46 B. coli per 

 cubic centimeter can in nine days free themselves from B. coli to 

 such an extent that there remains only 2.8 B. coli pr cubic centimeter. 

 This is well within the standard adopted by the Bureau of Chemistry 

 which allows oysters to be shipped in interstate commerce which 

 contain 4.6 B. coli per cubic centimeter of shell liquor. 



Experiment III. 



On November 8, 1913 a bushel of oysters were taken from Provi- 

 dence River and transplanted to Wickford. These oysters were put 

 into two galvanized iron baskets and hung into the water from the 

 floor of the Beacon Oyster Co. These oysters were suspended in the 

 water near the edge of the channel and located only a few yards from 

 the place where the oysters in the two previous experiments were 

 placed. A sample of ten oysters was taken from this lot and carried 

 to the laboratory for analysis. These ten oysters were found to be 

 badly polluted and had a score of 640. Samples were sent to the 

 laboratory and analyzed on November 10, 12, 14, 17, 19, 21 and 24. 

 The methods of analysis were the same as in the previous experi- 

 ments with two exceptions. The 1-10 c.c. and 1-100 c.c. dilutions 

 were made in duplicate, while the one cubic centimeter samples were 

 only inoculated singly. The oyster liquor was drained into glass- 

 stoppered bottles which were graduated so that the amount of liquor 

 could be read off in cubic centimeters. An equal amount of sterile 

 one per cent, sodium chloride solution was added and the bottle 

 shaken vigorously one hundred times. One cubic centimeter of this 

 mixture was used for the first inoculation and to make the proper 

 dilutions. As a result the quantities as given in the table are for the 

 mixture of shell liquor and salt solution. The amount of shell liquor 

 in the dilutions is not 1 c.c, 1-10 c.c. and 1-100 c.c, but }/2 c.c, 

 1-20 c.c. and 1-200 c.c. But as ten oysters were used the result 

 equals an analysis of five oysters where 1 c.c, 1-10 c.c. and 1-100 c.c 

 samples of the shell liquor were used. For comparative results, 



