SOURCES OF CONTAMINATION. 
7, 
TABLE 2.—Results of the bacteriological examination of hard clams (quahaugs) in the shell. 
COLLECTED FROM GROUNDS WHERE INSPECTION SHOWED NO SERIOUS POLLUTION. 
Sample number. 
Bacteria 
per cubic 
centimeter 
(plain agar 
incubated 
four days 
at 25° C.). 
300 
2,700 
32,000 
150, 000 
4,000 
4,000 
32, 000 
B. coli per 
cubic cen- 
timeter. 
ae) 
COLLECTED FROM GROUNDS SHOWING VERY SERIOUS POLLUTION UPON 
Clams appear to contain a larger number of bacteria in their liquor 
This may be explained in part 
INSPECTION. 
Saskia rel he A 13, 000 10 
Same ented 8 Mis SOU hh ae 11, 000 1,000 
ARGS etc 0 SE 1, 122, 000 1,000 
et ae ee ee ee en pre 2, 108, 000 10 
ieee Pee ey ee 100, 000 100 
Uae a NORE RORY ek eager SS 12, 000 100 
ao) SACS nye ere 60, 000 1,000 
489, 000 460 
and body contents than do oysters. 
by the fact that the clams in the latter table were collected from 
localities where extreme pollution was indicated. Each sample gen- 
erally represented at least five clams, which constituted a composite 
sample. Ina few instances only one or two large clams were obtained 
from a given locality for examination. 
TABLE 3.—Results of the bacteriological examination of sea water over oyster beds. 
COLLECTED FROM LOCALITIES WHERE INSPECTION SHOWED NO 
Sample number. 
Surface water. 
Approximate average 
SERIOUS 
POLLUTION. 
Deep water. 
Bacteria B. enteri-|| Bacteria B. enteri- 
per cubic | B. coli | tidisspo-|| percubic | B. coli | tidis spo- 
centimeter | per cubic} rogenes || centimeter | per cubic| rogenes 
(plain agar| centi- | percubic|| (plain agar| centi- | per cubic 
four days | meter. centi- four days | meter. centi- 
at 25° C.). ‘ meter at 25° C.). meter. 
30 0 0 130 0 0 
100 0 0 40 0 0 
20 0 0 30 0 0 
500 1 0 700 1 0 
100 0. 0 100 1 0 
200 1 0 300 i 0 
20 0 0 70 0 0 
15 0 0 40 0 0 
120 0.2 0 170 0.4 0 
72743°—Bull. 136—11——3 
