THE BACILLUS OF BUBONIC PLAGUE. 319 



iridescent,, transparent, and whitish. On gelatin at 

 18 20 C. it develops as small, sharply defined, white 

 colonies without liquefaction of the medium. In stab- 

 cultures it develops both on the surface and along the 

 track of the needle. Its growth is slow. It does not 

 cause a diffuse clouding of bouillon, but grows rather 

 as irregular, flocculent clumps that adhere to the sides 

 or sink to the bottom of the vessel, leaving the fluid 

 clear. It shows but limited growth on potato. It does 

 not ferment glucose with production of gas, nor does it 

 form indol. It coagulates milk. 



This organism is killed by drying at ordinary room- 

 temperature in four days. It is killed in three or 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. 1 



It is pathogenic for rats, mice, guinea-pigs, rabbits, 

 hogs, horses, monkeys, cats, chickens, and sparrows. 

 Pigeons, hedgehogs, and frogs are immune, and dogs 

 and bovines are apparently so. 2 Animals succumb to 

 subcutaneous inoculation in from two to three days. 

 According to Yersin, the site of subcutaneous inocu- 

 lation becomes oedematous and the neighboring lym- 

 phatics are 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 



1 See " Viability of the Bacillus Pestis," by M. J. Eosenau, U. S. 

 Marine-Hospital Service, Bulletin No. 4, of the Hygienic Laboratory, 

 U. S. M.-H., Washington, D. C., 1901. 



2 Nuttall: Centralblat fiir Bakteriologie und Parasitenkumle, 18M7, 

 Abt. i. Bel. xxii. S. 1)7. 



