82 BACTERIOLOGY OF THE OYSTER. 



were fitted to all the dishes and during the process two of the oysters 

 closed. The other one remained open even after reaching the 

 laboratory. After the cover was removed and the shell touched with 

 a glass rod it closed immediately. A heavy precipitate was found on 

 the bottom of each of the dishes and a great deal of mucus was seen 

 in suspension. This matter could not have come from the outside 

 of the oyster, because they were thoroughly cleaned before the 

 experiment began. There is no question but what the oyster had 

 opened; three were found open and two of them closed immediately 

 upon being agitated. The other three must have opened in order 

 to discharge so much mucus, but had closed again of their own 

 accord at 34°F. 



Two oysters were infected with B. coli and put into dishes in cold 

 storage January 20. The dishes were later found to be cracked and 

 the water leaked out. These two oysters were brought to the 

 laboratory April 17. One was put into a dish of sea water, while 

 the other was opened and two cubic centimeters of the juice was 

 inoculated into each of four bile tubes. Gas appeared in each tube 

 and typical B. coli was isolated on litmus-lactose-agar plates. This 

 was eighty-seven days after infection. The other oyster opened 

 before morning, but was apparently dead for it would not respond to a 

 mechanical stimulation of its gills and mantle. When opened both 

 oysters appeared plump and in prime condition. From their appear- 

 ance they could not have been told from oysters freshly caught. 



From these experiments the writer believes that oysters do close 

 their shells for varying periods, depending upon the temperature. 

 Whether they close their shells under natural conditions when the 

 temperature falls around 0°C. no one has determined. That they do 

 not lose control of their adductor muscles is demonstrated in both 

 experiments. The writer is lead to believe that there is no definite 

 period at which this phenomenon can be said to begin. Mitchell 

 in an unpublished observation states that with a temperature below 

 20°C. oysters get "nervous" and will close upon the slightest provo- 

 cation and remain closed for fairly long periods. It appears that at 

 this temperature the irritability of the oyster is much increased. 



These experiments lead one to conclude that the so-called period 

 of hibernation of the oyster is a relative term. The length of time 

 that they remain closed depends upon the temperature which deter- 

 mines the rapidity of the oxidative and other metabolic processes of 

 the oyster. An oyster will remain closed as long as its supply of 



