BACTERIOLOGY OF THE OYSTER. 79 



when the temperature of the water approaches 0°('. was first put 

 forward by Gorham in 1910;^ to explain certain bacteriological find- 

 ings in Providence River oysters. It was found, that during the 

 warmer months the oysters in certain parts of the river were badly 

 polluted, but in January, with the temperature of the water around 

 0°C., the oysters were found free from colon bacilli. In order to 

 explain this phenomenon Gorham advanced the theory that when the 

 temperature of the water approaches 0°C. the oyster closes its shell 

 and remains closed until the temperature of the water begins to rise 

 and then it opens its shell and resumes its normal activity. This 

 period was called its "Hibernation Period." A little later Pease, ^ 

 Field, of the Massachusetts Fish and Game Commission, and others 

 advanced a similar idea. So far as the writer is aware, however, no 

 experiments have been tried to confirm or deny this theory. The 

 experiments of the writer cited elsewhere on the cleansing of polluted 

 oysters seem to show that oysters do remain closed for several days 

 with a temperature of about 5°C. But in order to throw further 

 light upon the matter the following experiments were tried. 



Experiment I. 



January 12, fourteen oysters were placed in sea water which had 

 been inoculated with a pure culture of B. coli. The oysters were 

 left in the sea water a day and a night. They were removed January 

 13th, and the outside of the shells scrubbed thoroughly with a stiff 

 brush and running tap water and were then put into a strong solution 

 of calcium hypochlorite for one-half hour and stirred up about once 

 a minute. They were then put into 7% formalin for the same length 

 of time and stirred with a glass rod for a few seconds at about one 

 minute intervals. They were then washed for a considerable time in 

 fast running tap water, temperatures between 7°C. and 8°C., and 

 stirred at intervals of two or three minutes. The oysters were then 

 taken (Jan. 13), to a cold storage room of the Merchant's Cold 

 Storage and Warehouse Co., Providence, and put into storage at 

 34°F. (about 1.1°C.) The temperature of the room is maintained 

 constant throughout the year and is never allowed to vary more than 

 .5°F. The next day sterile sea water which had been kept in the 



^(l) Report of Commissioners of Shell Fisheries of R. I., 1910. (2) Seasonal Variation in the 

 Bacterial Content of Oysters, Am. Jour. Pub. Health, II, 1910, 24. 



^Some Bacteriological Problems in the Oyster Industry, The Fishing Gazette, 28, 1911, 865. 

 July 15. 



