162 EXPERIMENT STATION RECORD. 



Sources of coritamiiiMtiou and similar questions arn discussed and fhe results 

 of coolving tests on the bacteriological content of shellfish are reported. The 

 bulletin contains a digest of data on sewage contamination and an extended 

 bibliography. 



Quotations from tlie author's summary follow : 



" There is undisputed evidence to show that shellfish become contaminated 

 when placed in sewage-polluted water, and that Bacillus coli and B. typhosus 

 will survive for variable lengths of time in the liquor and the body contents of 

 such shellfish after their removal from infected water. 



" The presence of sewage organisms in oysters and other shellfish, even in 

 small numbers, may be indicative of great danger; for, where such oi'ganisms 

 exist, the specific cause of enteric fever and allied disorders may also be 

 found. . . . 



" The indiscriminate introduction of sewage into our natural bodies of water 

 is now the greatest enemy to the shellfish industries. In order to correct this 

 evil it will be necessary to prevent further pollution of our waters, or else to 

 remove the shellfish industries from the grounds subject to pollution. 



" Oyster beds should be protected from every possible source of contamina- 

 tion, and they should be located in water proven to be pure by repeated exami- 

 nations. . . . 



" The practice of fioating oysters in water of questionable purity should be 

 absolutely prohibited because of the probability of sewage contamination. When 

 it is desired to remove the gross filth from the exterior of the shell, oysters 

 may be floated and allowed ' to cleanse themselves ' in suitably constructed 

 devices in waters free from pollution, and containing no less salt than the 

 water in which they will gi*ow to maturity. 



" Like other perishable food products, oysters may become unfit for use if 

 stored or kept under insanitary conditions. This spoilage, however, may take 

 place wholly from the length of time out of water. 



" Oysters removed from pure beds may become contaminated during the 

 process of shucking or preparation for the market in insanitary shucking es- 

 tablishments. . . . 



" The liquor in the shell surrounding the oysters contains more bacteria than 

 does an equal volume of meat from the same oyster. This liquor, together with 

 any sand in the gills of the oyster, can be removed and the meat chilled at the 

 same time by the use of pure ice and water. This washing process can be done 

 efliciently within 3 to 10 minutes, depending upon the method employed. Oys- 

 ters should not be allowed to soak in fresh water, as they increase in volume, 

 change in appearance and flavor, and decompose more rapidly than those not 

 soaked. 



" [As shown by cooking tests], steaming contaminated oysters and clams in 

 the shell, or cooking them after shucking for 15 minutes at boiling tempera- 

 ture, practically destroys all organisms of a questionable character, but since 

 in practice shellfish are never cooked for this length of time, cooking can not 

 be depended upon to remove this danger. 



" Oysters intended to be eaten on the half shell, above all others, should be 

 produced from beds of unquestionable purity, and they should be consumed 

 preferably while fresh from the beds; although if properly kept at cool tem- 

 peratures under sanitary surroundings shell oysters may remain wholesome 

 and in good condition for several weeks after dredging. 



"The investigations show that vast areas of valuable shellfish grounds in 

 this country are now reasonably free from sewage pollution, but this territory 

 will gradually diminish in size if sewage is not properly cared for in the 

 future. Comparatively si)eaking, only a small acreage is now subject to serious 

 pollution." 



