THE PLAGUE. 253 



spleen, and blood. Guinea-pigs die in from two to five days, and 

 mice in one to three days. 



In guinea-pigs after some hours there is oedema at the seat of 

 inoculation, and the lymphatic glands are swollen. After twenty - 

 four hours the animal refuses to eat, has a staring coat, and after 

 a time suddenly falls on its side, and is attacked by convulsions, 

 which become more and more frequent until death occurs. 



After death the seat of inoculation is found to be extensively 

 cedematous, and the neighbouring lymphatic glands enlarged and 

 filled with bacilli. The intestine is often congested, and the liver is 



Fig. 123. — Bacilli or Pl.^gue and Phagocytes, x 800. 

 From human lymphatic gland. (Aoyama.) 



congested and enlarged. In less acute cases an abscess of the 

 abdominal wall occasionally resvilts. 



The bacilli are sometimes found in the pleural and peritoneal 

 exudation. The liver and spleen also contain many bacilli. Those 

 in the blood are a little longer than those in the lymphatic glands. 



Inoculations can readily be made from guinea-pig to guinea- 

 pig by using the pulp of the spleen, or the blood. Cultures lose then- 

 virulence gradually, but the virus can be intensified by successive 

 inoculations in animals. The disease is infectious to mice as 

 well as inoculable. Pigeons are insusceptible. Rats and flies may 

 convey the bacilli. 



According to Aoyama, the bacilli found in the blood of plague 



