SEWAGE CONTAMINATION OF OYSTER BEDS. 229 
river were infected. Seventy-four per cent of the water samples 
taken over the Sabins Point oyster ground, directly across the river 
from Pawtuxet, gave positive tests for B. “Coli Seventy per cent of 
the ovsters from this ground contained this organism within their 
shells. 
Fifty-nine per cent of the water samples taken over the Bullock 
Neck oyster beds, 2 miles below Sabins Point, contained £2. col/. 
This organism was isolated from 53 per cent of the oysters obtained 
from this locality. 
Fifty per cent of the water samples collected on the Conimicut 
Point oyster beds, but only 32 per cent of the oysters from this source 
contained LB. cold. 
Off Nayatt Point, 55 miles south of Fields Point, the water is much 
freer from sewage pollution. Thirty-one per cent of the water sam- 
ples and only 23 per cent of the oysters taken from this part of the 
river contained colon bacilli. | 
The Warren River, however, is a polluted stream, 2. co/7 being fre- 
quently found ina series of samples taken at intervals from the mouth 
of this river to the town of Warren; and also in a sample taken in 
the Providence River in the flow of the tide from the Warren River, 
though this pollution is soon swallowed up in the larger volume of 
the Providence River, so that no trace of B. coli can be found 2 miles 
distant from the entrance of the Warren River. The bacillus was 
found in over 60 per cent of the oysters taken from the Warren River 
beds. 
On the western side of the river, 6 to 8 miles below the sewer out- 
let, 2. colt is found only occasionally and then ona falling tide. It 
was present in only one oyster from this section of the river. 
From the above data it may be noted that the zone of sewage pol- 
lution of the Providence River reaches southward from the Fields 
Point sewer outlet for a distance of about 6 miles. 
In Narragansett Bay proper a different set of conditions exists. 
The western passage is free from sewage pollution, and neither the 
water nor oysters at Prudence Island or Wickford are infected with 
the colon or other sewage bacteria. 
The Fall River sewer is, of course, the principal source of contami- 
nation of the waters of Mount Hone Bay, but it is at least 4 miles 
away from the nearest oyster bed, and the water and oysters from the 
Kickemuit River are not found to be infected with any sewage bacteria. 
In the sample from the Narrows, the entrance to Mount Hope Bay, 
BL. coli was found in a single instance. Two oysters from the beds 
situated off the shore of Bristol Ferry were infected. 
