274 BACTERIOLOGY. 



lymphatics enlarged in a few hours. After twenty-four 

 hours the animal is quiet, the hair is rumpled, tears 

 stream from the eyes, and later convulsions set in which 

 last till death. The results found at autopsy are : blood- 

 stained oedema at the site of inoculation, reddening and 

 swelling of the lymphatic glands, bloody extravasation 

 into the abdominal walls, serous effusion into the pleu- 

 ral and peritoneal cavities; the intestine is occasionally 

 hypersemic, the adrenal bodies congested, and the spleen 

 is enlarged, often showing the presence of grayish points 

 suggestive of miliary tubercles. The plague, or pest, 

 bacillus is to be detected in large numbers in the local 

 cedema, the lymph glands, the blood, and the internal 

 organs. 



As is the case with the group of hemorrhagic septi- 

 csemia bacteria, when death does not result promptly 

 after infection there is usually only local evidence of 

 the inoculation, the distribution of the micro-organisms 

 throughout the body being considerably diminished. 



It is said that when virulent cultures are employed 

 animals may sometimes be infected by way of the ali- 

 mentary tract. 



This organism is killed by drying at ordinary room 

 temperature in four days. It is killed in three to four 

 hours by direct sunlight. It is destroyed in a half hour 

 by 80° C, and in a few minutes by 100° C (steam). 

 It is killed in one hour by 1 per cent, carbolic acid 

 and in two hours by 1 per cent, milk of lime. 



The bacilli apparently lose their virulence after long- 

 continued cultivation under artificial circumstances, 

 and it is said that from slowly developing, chronic 

 buboes non-virulent or feebly virulent cultures are 

 often obtained. Variations in the degree of virulence 



