78 BACTERIOLOGY OF THE OYSTER. 



coli from 73 per cubic centimeter to one per cubic centimeter in six 

 days. In another experiment with an average temperature of 13°C. 

 during the period of investigation the oysters showed an eUmination 

 of B. coh from an average of 46 B. coh per cubic centimeter to 7.3 B. 

 coU per cubic centimeter in four days and to 2.8 per cubic centimeter 

 of shell liquor in nine days. As no examination was made between the 

 fourth and ninth day, it is quite possible that the limit of possible 

 elimination was reached sometime before the ninth day. No doubt 

 an examination on the sixth or seventh day would have shown a B. 

 coli content sufficiently low to pass the standard set by the Bureau of 

 Chemistry of the Federal Government. 



In another experiment in November, 1912, with an average tem- 

 perature 5.4°C. twelve days was not sufficient to eliminate B. coli to 

 any appreciable extent. The examination on the twelfth day showed 

 a very marked decrease in the number of B. coli, but as no subsequent 

 examinations were made it is not possible to say with authority 

 whether this was the beginning of an elimination process or not, 

 though the writer is led to believe such was the case. The interesting 

 feature of this experiment is that no elimination took place in nine 

 days, while in the other two experiments a very marked reduction 

 took place in six days in one case and in five and nine days in the other 

 case. 



These sets of experiments seem to throw some light upon the so- 

 called hibernation of the oyster. With an average temperature of 

 13°C. in one case and 9.7°C. in the other the oysters opened and began 

 to eliminate B. coli almost immediately, but in the first experiment 

 with an average temperature of 5.4°C. no reduction in B. coli was 

 found until the twelfth day. These experiments lead the writer to 

 beheve that when the temperature of the water is somewhere between 

 9°C. and 5°C. oysters close their shells for a longer or shorter period. 

 But from experiments detailed elsewhere, the writer believes that 

 there is no time above 0°C. when oysters close their shells for an 

 indefinite period. The length of time that oysters remain closed is in 

 inverse proportion to the temperature which determines the rapidity 

 of the metabolic processes going on within the oyster. 



EXPERIMENTS ON THE HIBERNATION OF THE OYSTER. 



The so-called hibernation of oysters has attracted much attention 

 during the last four years. The theory that oysters close their shells 



