100 NEW YORK ZOOLOGICAL SOCIETY. 



oyster was normal in every respect, and its heart was pulsating 

 when opened. In oyster No. 2, 25 per cent, of the organisms iso- 

 lated from it were found to be Bacillus typhosus. On opening 

 this oyster no signs of life could be detected. No. 3 was dead be- 

 yond doubt, and had turned black ; and in this case all organisms 

 tested were found to be B. typhosus. 



The two little-neck clams examined looked normal in every 

 way, except that no pulsation could be noticed in clam No. 2. No 

 typhoid bacilli could be found in No. 1, whereas No. 2 showed all 

 organisms to be B. typhosus. 



It was seen from this that this method of infecting the tanks 

 could not be used, so in all further work the tanks were infected 

 in the following manner : 



The bacilli were sown on agar planted in flasks. They were 

 incubated for 24 hours. At the end of 24 hours about 20 c.c. of 

 sterile sodium chloride solution was placed in the flask, and the 

 growth washed off the agar into this solution. This was poured 

 into the tank, and more fresh sodium chloride solution placed in 

 the flask, to wash the remaining bacilli off, as the whole growth 

 could not be removed at the first washing. This was also added 

 to the tank. 



After this the oysters were removed at the end of certain pe- 

 riods for examination. After the first experiment five oysters 

 were removed each time. These were washed and scrubbed to re- 

 move as many organisms as possible from the shell. The oyster 

 was then opened by cracking off the edge and inserting a sterile 

 platinum needle and stirring it around, then draining the juice 

 into a sterile beaker glass. One-tenth of a c.c. of this juice was 

 used to inoculate each tube of plate media. The plates were in- 

 cubated for 48 hours, and then either 20 or 40 colonies were 

 planted in bouillon — that is, 20 or 40 colonies from each oyster of 

 the 5 removed, making either 100 or 200 colonies examined. At 

 the end of 24 hours the bouillon cultures were tested in the hang- 

 ing drop, with the serum of a young goat immunized to B. typho- 

 sus, and having great agglutinative power for this organism. The 

 dilution used was 1-800. If the organisms in the tube did not 

 agglutinate, they were thrown out, and no further test was made 

 on them. If they showed agglutination, they were planted in 

 Dunham's solution, and tested for indol, also in lactos bouillon 

 for gas production, and in milk for coagulation ; but later in my 

 work I relied wholly on the agglutination test. 



It will be seen from Chart I, that when the oysters remain in 

 the infected water the B. typhosus may remain present until the 



