THE PLAGUE. 253 



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

 mice in one to three day.s. 



In guinea-pigs after some hours there is cedema 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 

 oidematous, and the neighbouring lymphatic glands enlarged and 

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



I* V'v - . 



ft 



*'.■. 



Fig. 12.3. — Bacilli of Plac4Ue and Phagocytes, x 800. 

 From human lymi^hatic gland. (Aovajia.) 



congested and enlai-ged. In less acute cases an abscess of the 

 abdominal wall occa.sionally results. 



The bacilli are sometimes found in the pleural and peiitoneal 

 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 theii- 

 virulence gradually, but the viru.s can be intensified by successive 

 inoculations in animals. The disease is infectious to mice as 

 well as inoculable. Pigeons are insusceptiljle. Eats and flies may 

 convey the bacilli. 



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



