34 SHELLFISH CONTAMINATION FROM SEWAGE-POLLUTED WATERS. 
ined, and some proved to be satisfactory, while others were unfit for 
such purposes. The bacteriological condition of water can only be 
determined by making the necessary examinations. Most large 
cities have records of the bacterial content of their water supply, and 
if such waters were being used for washing shellfish the oystermen 
could inform themselves as to its purity from the records of the city 
health office. | 
That the hquor bathing the meat of the oyster contains more 
bacteria per given volume than does an equal volume of minced 
oyster meat is shown in Tables 10 andil. A brief, brisk washing, 
not to exceed 3 or 5 minutes in duration, is usually sufficient to 
remove this liquor, and also the adhering sand and grit which may 
be clinging to the gills of the oyster. It is not necessary to soak 
oysters over night in order to wash them. Soaked oysters, like 
floated oysters, deteriorate more rapidly than do those which have 
not been so treated. Oysters may be washed two or three times 
before finally reaching the consumer. The total length of all the 
combined washings should not exceed 30 minutes, and pure iced 
water should be used. The efficiency of any washing device or 
method depends largely on its mechanical points, and the amount 
of soakage taking place will vary with the manner of washing, the 
relative quantity of oysters and water used, and the eee 
of the wash water. 
Tables 10 and 11 illustrate the relative bacterial content of the meat 
and liquor of shellfish, Table 11 being considered with special refer- 
ence to the development in plain and in saltless agar. 
TaBLE 10.—Bacterial content of oyster meat and oyster liquor compared. 
| 
Oyster meats. i] Oyster liquor. 
| Bacteria per cubic Bacteria per cubic 
centimeter after | centimeter after 
four days’ incuba- . || four days’ incu-| 4; : 
tion. B.coli || bation. B. coli 
Sample per cubic | per cubic 
No. |---| ecenti-  |}—_———_| centi- 
| meter. || sete meter. 
Plain agar ma le salt Plain agar le salt 
omen ey. || eA Pathe Caleta oe 
SiG | | a 2 ieee 
| 
| i =F 
ee eee 2, 800 | 30 | 1 || 55,000 | 34,000 10 | 
2 10,900 | 90 | 1 |} 13,500 | 1,200 10 
5s Saye 3, 700 2 | 1 |} 93,600 30 10 | 
Y pees 1,200 | 6 | 1 || 4,200 70 10 | 
EG eAcuae 2,000 20 | 1 |} 3,800 300 1 
6h 1000 ie aaa O->}| 445000" |e 2 eee 0 
Teneo) 2000 ose ee D7 0007 | ee 0 
Approxi- 
mate | 
aver- =i 
age.. 4,300 30 0.7 31, 000 7,120 5.9 
} 
The results show that the oyster liquor in these samples contained 
more than seven times as many organisms per given volume as did 
