BACILLUS PESTIS 395 



results found at autopsy are: blood-stained edema at the 

 site of inoculation, reddening and swelling of the lymphatic 

 glands, bloody extravasation into the abdominal walls, serous 

 effusion into the pleural and peritoneal cavities; the intes- 

 tine is occasionally hyperemic, the adrenal bodies congested, 

 and the spleen enlarged, often being studded with grayish 

 points, suggestive of miliary tubercles. The plague, or pest, 

 bacillus is detected in large numbers in the local edema, the 

 lymph glands, the blood, and the internal organs. 



As is the case in general with the group of hemorrhagic 

 septicemia bacteria, the members of which it resembles in 

 certain other respects, when death does not result promptly 

 after infection there is usually only local evidence of the 

 inoculation, the distribution of the microorganisms through- 

 out the body being considerably diminished. 



Animals that survive inoculation with this organism 

 usually exhibit a certain degree of immunity from subsequent 

 infection. 



Nuttall 1 notes that feeding experiments have resulted 

 in fatal infection in gray and white rats, house- and field- 

 mice, guinea-pigs, rabbits, hogs, apes, cats, chickens, sparrows, 

 and flies. He also calls attention to the fact that flies may 

 live for several days after being infected with this organism, 

 and if at liberty to fly about may infect persons or foodstuffs 

 on which they alight or fall. 



All opinions and investigations agree in that the flea is the 

 most common and important of the agents of transmission, 

 carrying the disease from man to animals (rodents, rats in 

 particular) and from animals to man. 



The bacilli apparently lose their virulence after long-con- 



1 Loc cit. 



