228 EEPOKT OF THE COMMISSIONER OF FISHERIES. 



Practical!}" all of the clams and mussels analyzed as representing- the 

 condition of shelllish on the Pawtuxet shore, 2 miles below the city 

 sewer, were infected with colon bacilli; but 70 per cent, however, of 

 the oysters taken on the Sabins Point oyster ground, which lies directly 

 across the river from Pawtuxet Neck, were thus infected. 



Fifty-three per cent of the oysters collected from the Bullock Neck 

 layings, about -i miles south of Fields Point, contained B. colt. 



Thirty-two per cent of the oysters obtained from the Conimicut 

 Point ground, 1^ miles below the locality where the oysters from the 

 Bullock Neck layings were dredged, contained colon bacilli. 



Twentj^-three per cent of the specimens dredged on the Nayatt Point 

 oyster beds were infected. 



On the other hand, oysters from the Pocky Point ground, 6 to 8 

 miles below the chief source of sewage contamination of the river, are 

 practicallj" free from pollution. B. coll was isolated from but one 

 specimen of a lot of 32 oysters which were obtained from these grounds. 



A sharp rise in the percentage of oysters infected with sewage 

 foritTs was noticed when specimens from the Warren River were ana- 

 lyzed. Five out of a total of 8 oysters examined were infected with 

 B. coll. ^ • 



Oysters from Prudence Island and Wickford Harbor do not cotj- 

 tain B. coll or other sewage bacteria. 



Oysters from the Kickemuit lliver were not infected with these 

 organisms. Only a small percentage of the specimens taken from the 

 layings in the entrance of Mount Hope Bay contain any trace of sew- 

 age bacteria. 



COMPAEISON OF RESULTS OF WATER ANALYSIS AND SHELLFISH ANALYSIS. 



If we consider the presence of B. coll in waters and food stuffs an 

 indication of sewage contamination, we may trace the distribution of 

 sewage in the Providence Piver and Narragansett Bay as follows: 

 Starting in the neighboi'hood of Fields Point and proceeding grad- 

 ually down the river to the bay below, we find that all water samples 

 taken within a radius of one-half to three-quarters of a mile from the 

 Providence city sewer outlet contain'^, coll^ and often other species 

 of bacteria commonly found in sewage. B. coll was abundant, not 

 only in the water about Fields Point, but was readily isolated from 

 samples of sand taken from the beaches near b}"; also oysters col- 

 lected from these highly polluted waters, and clams and mussels from 

 the shores within half a mile from the sewer outlet, without exception, 

 contained B. coll^ and in many cases other sewage bacteria, within 

 their shells. 



Nearly all the water samples collected at Pawtuxet Neck, about 2 

 miles below Fields Point, were found to contain B. coll; also most 

 of the shellfish (clams and mussels) obtained from this section of the 



