Fluctuations of Virulence 



27 



(b) Was inoculated with 0.1 c.c. of an emulsion of the brain 

 of (a). 24 hours later, it was sick and unsteady on its feet; 

 blood culture was negative. 48 hours later nervous symptoms 

 were very marked, consisting of ataxia and increased irritability; 

 it was so sick in the afternoon of this day that we killed it with 

 ether. At autopsy cultures from the brain and heart's blood 

 were negative. 



(c) Received 0.1 c.c. of heavy emulsion of organisms from 

 a chocolate agar slant, inoculated from organism recovered 

 from brain of (a). Blood cultures were positive 6 hours, 24 

 and 48 hours after inoculation, but were negative at 72 and 96 

 hours. The animal was sick 24 hours later, showing ataxia 

 and dyspnea; it became progressively worse, developing a stiff 

 neck and finally was killed with ether four days after inocula- 

 tion as it was so sick. At autopsy, the brain at the site of in- 

 oculation showed an area of yellowish friable material 0.3 cm. 

 in diameter, extending 0.2 cm. into the substance of the cor- 

 tex. Cultures from the brain were positive, but the heart's 

 blood was negative. 



(d) Inoculated with 0.1 c.c. of emulsion of brain of (b) 

 which was shown to be sterile. At the end of three days, it 

 developed diarrhea and looked sick; two days after this, ,it died. 

 At autopsy the brain at the inoculation site showed an area of 

 yellowish friable material 0.2 x 0.1 cm. Smears and cultures 

 of this area, the ventricular fluid and the heart's blood were 

 negative. 



3. By stomach tube. One animal was given 20 c.c. of a 

 20 hour growth in chocolate broth. It was never sick. Blood 

 culture seven hours after inoculation was negative. 



C. Experiments with strain "J" : 



1. Intracerebral. One animal was given 0.1 c.c. of a 20 

 hour chocolate broth culture. Blood culture was negative 24 

 hours later. It never was sick. 



2. By stomach tube. One rabbit received 27.5 c.c. of a 20 

 hour chocolate broth culture and never was sick. 



D. Experiments with strain "Z" : 



1. Intracerebral. One rabbit received 0.1 c.c. of a 20 hour 

 chocolate broth culture. He developed no symptoms so that 3 

 days later was given 2 c.c. of a similar culture intraperitoneally ; 

 following this, blood cultures 5 hours and 24 hours later were 



