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Scientific Proceedings (125) 



negative. As he was not very sick after the second inoculation, 

 'he was again injected intraperitoneally with 2 ex. of a chocolate 

 broth culture in the morning, and 4 ex. of the same culture in 

 the afternoon. The following day he was perfectly well. 15 

 days after his brain inoculation, he developed paralysis of the 

 hind legs, his respiration was labored and in general he was so 

 sick that we etherized him to death. At autopsy, the brain alone 

 showed any pathological changes; at the inoculation site there 

 was a yellowish caseous area 0.2 x 0.2 x 0.1 cm. Smears and 

 cultures of this area and the heart's blood were negative. 



A second rabbit was given 0.2 ex. of an emulsion of the 

 brain of the preceding rabbit. He never developed any nervous 

 symptoms, but a week later developed diarrhea. He did not die. 



Discussion. 



On comparing the results of I and II, the striking difference 

 in virulence will be noted. In II we were unable to kill or even 

 make sick with intratracheal or stomach inoculations, and while 

 we killed one animal with an intracerebral inoculation, in this 

 case we used a very large dose, and the animal did not develop 

 a septicaemia a few hours later as did the animals in I. On the 

 whole, the results in II closely resembled those obtained with 

 the strains we worked with in III. 



There is one interesting feature in the less virulent group 

 which deserves attention, namely, that in two animals that de- 

 veloped a septicemia 24 hours and 58 hours after inoculation, 

 this septicaemia then cleared up and yet the animals died, in one 

 instance at least, all cultures being negative at autopsy. Three 

 rabbits inoculated intracerebrally, one rabbit inoculated intra- 

 pleurally and a mouse injected with sputum containing numerous 

 B. influenza died with negative cultures at autopsy. This is an 

 important point, especially in connection with human cases, for 

 it brings up the possibility that an individual may die of an in- 

 fection with B. influenza and yet all cultures at autopsy fail to 

 show evidence of this organism. The most probable explanation 

 of this seems to be that at first when the organisms are growing 

 they elaborate a poison causing a fatal injury, and then later 

 the defenses of the body or some other factor kills off the or- 

 ganisms, but too late to prevent death as the injury has been 

 done. 



