BACTERIOLOGY OF THE OYSTER. 7 



between Nos. 1 and 5. It will further be noted that in oysters Nos. 1 

 and 3 B. prodigiosus was isolated from the cloacal chamber (hole No. 

 2) before it was found in hole No. 1, although the distance between 

 holes Nos. 5 and 2 was also about twice as far as between 5 and 1 . In 

 no case did B. prodigiosus appear at hole No. 1 before it did at No. 2. 



Series III. 



A third set of experiments were now performed in order to show 

 that bacteria can pass from the cloacal chamber to the gill chamber 

 and to ascertain, if possible, the avenue through which this takes 

 place. In this experiment two oysters were used and secured to the 

 bench in the same manner as in the previous experiments. Three 

 holes were bored into the branchial chamber as indicated by the 

 Nos. 1, 5 and 4 in the plate. One hole was bored into the 

 cloacal chamber as indicated by No. 2 in the plate. Control 

 inoculations were made as before from these four holes. These 

 showed no colonies of B. prodigiosus. A loopful of B. prodig- 

 iosus was placed in hole No. 2, and loopfuls were taken from holes 

 Nos. 1, 5 and 4 at intervals of two minutes for fourteen minutes. 

 The results are shown in table No. 2. 



Table No. 2. 



Showing the time at which B. prodigiosus was recovered from holes 

 Nos. 1, 5 and 4 after inoculation of the cloacal chamber at hole No. 2. 



+ ^ presence of B. prodigios 



= absence of B. prodigiosus. 



