286 PHILIP HADLEY 



As a final test, in order to explain, if possible, the discrepancies 

 between Bull's results and those of the present writer, it seemed 

 desirable to repeat the experiment with the same culture used 

 by Bull. Fortunately, as a result of the careful records kept by 

 the laboratory of the Curator of Public Health, at the American 

 Museum of Natural History, it was possible to locate the culture 

 used by Bull, who had in the meantime discarded his strain, 

 and to obtain a subculture, together with a brief history of 

 organism. This seemed especially desirable in view of the many 

 errors that are made in the recognition of the organism of the 

 authentic fowl cholera. It can scarcely be doubted that the 

 majority of the cultures so labelled, that may be obtained from 

 any laboratory, are not B. avisepticus. 



Upon receipt of the culture it was plated and subcultured in 

 chicken agar. Flasks of chicken broth were inoculated and incu- 

 bated for forty-eight hours at 37°C. One of the cultures was 

 then passed through a Berkefeld N-candle under suction and 

 this filtrate tested for sterility. The filtrate was then divided 

 into two portions, one of which was inoculated at 37°C. over night 

 as a final test of sterility; the other kept in the ice-box. The 

 following morning, all evidences having pointed toward the 

 sterility of the filtrate, a 1.5 cc. sample was injected intraven- 

 ously into a 1375-gram rabbit, which died in less than three hours 

 with symptoms of intoxication. 



Another rabbit of 1347 grams was inoculated intravenously 

 with 0.7 cc. of a twenty-four-hour chicken broth culture of Dr. 

 Bull's strain and no ill effects resulted. Apparently 1.5 cc. of a 

 forty-eight-hour culture-filtrate contained a lethal dose of toxin, 

 while 0.7 cc. of a twenty-four-hour culture did not. This is sug- 

 gestive of an endotoxin rather than an exotoxin. To demonstrate 

 this further, a forty-eight-hour culture of Dr. Bull's strain was 

 shaken for one-half hour, incubated at room temperature for forty- 

 eight hours and shaken again for three hours. It was then passed 

 through a Berkefeld N-candle and the filtrate tested for sterility 

 by subcultures. Of the sterile filtrate 0.5 cc. was then injected 

 into the ear vein of a lOOO-iram rabbit. One hour after the 



