BACTERIOLOGY OF THE OYSTER. 



Table No. 1. 



Showing the time at which B. prodigiosus teas isolated from the 

 different holes after inoculation of the gill chamber at hole No. 5. 



Oyster No. 



Hole No. 

 Control . 



2 min . . 



4 '•• . . 



4 

 



+ 

 + 

 + 



+ + 



1 2 







+ 



+ 



+ + 



+ + 



3 

 

 



+ + 



+ + 

 + + 



+ 1 + 



+ 1 + 



4 1 



o! 



0^ 



+ 

 + 

 + 



+ 

 + 



+ 



+ 



-f- = presence of B. prodigiosus. ■= absence of B. prodigiosus. 



From this table it is seen that in oysters Nos. 1 and 2 B. prodigiosus 

 was isolated from all the holes at the end of four minutes; in oyster 

 No. 3 at the end of six minutes, and in oyster No. 4 not until the end 

 of fifteen minutes. Oyster No. 4 was a long narrow oyster and hole 

 No. 3 in this case wfis necessarily moved further into the middle of 

 the oysters, so that the opening came nearly over the stomach, and so 

 did not reach the cloacal chamber. In the other cases, hole No 3 was 

 made nearer the edge of the oyster and close to the free edge of the 

 mantle, so that there was much greater chance of bacteria reaching 

 the hole from the liquor between the free edges of the mantle, for 

 the edges of the mantle are everywhere free except, at the "head" end, 

 where the the edges fuse and form a hood, which is attached to the 

 body by a flap of tissue. Between the free edges of the mantle and 

 between the hood and the body there is a space which extends around 

 the whole oyster and forms a kind of moat or trench filled with the 

 liquor in which bacteria can and do move by the currents set up by the 

 ciliary mfechanism of the oyster, which will be described a little later. 

 It will also be noticed that in every oyster of this series B. prodigiosus 

 was isolated from hole No. 4 before they were from hole No. 1. although 

 the distance between holes Nos. 4 and 5 were nearly twice as far as 



