62 BACTERIOLOGY OF THE OYSTER. 



The results are so irregular that we can draw no very specific 

 conclusions. It appears that in the first two weeks there is no initial 

 decrease but rather a steady increase in the total number of bacteria 

 present. This increase is also apparent in the ST^C. count and the 

 "red" count. On January 27, fifty-three days after the beginning 

 of the experiment there was a remarkable change in the proportion 

 of bacteria in the "washing" as compared with the shell liquor in 

 all except the B. coli count. The detailed analsyis for this date 

 shows that oyster number nine is responsible for this marked change. 

 It is very probably that this oyster had died and decomposition was 

 taking place. 



The B. coli count shows a decrease on the fourth day, but this 

 decrease is not particularly marked and may well be due to variations 

 in the oysters and not to an actual decrease. This is all the more 

 likely when it is found that on the seventh day the number of B. coli 

 is approximately the same as on the first day. The subsequent 

 examinations show that the number of B. coli is about one-half the 

 initial number and remains fairly constant throughout the experi- 

 ment. In the last analysis made, eighty days after the beginning of 

 the experiment, all the bile tubes showing gas after twenty-four hours 

 incubation were tested for B. welchii by inoculating a cubic centimeter 

 of the bile into freshly sterilized milk tubes and incubating anaerobi- 

 cally. No visible change took place in the milk after eighteen hours 

 incubation. It was a noticeable fact that not over ten per cent, of the 

 tubes showing gas after twenty-four hours incubation had one 

 hundred per cent, of gas, the amount said to be characteristic of 

 B. welchii. Most of the tubes had about fifty per cent. gas. From 

 these facts it appears that the fermentation was caused by some mem- 

 ber of the B. coli group and not by B. welchii. It is not surprising 

 to find that B. coli should live eighty days in oysters under such 

 conditions for Clark^ has shown that B. coli will live in ten per cent, 

 sewage eighty-four days. and in fifty per cent, sewage one hundred and 

 sixty-six days. Unpublished results from this laboratory show that 

 B. coli will live in sea water for one hundred and eighty days. The 

 writer has shown in the experiments on the hibernation of the oyster 

 that B. coli will live in oysters kept at 1.5°C. for at least one hundred 

 days. 



^Report of State Board of Health of ^lass., 1905, p. 455. 



