i THE ESSENTIAL CAUSE 9 



veins. In the lungs there occur lobular patches of con- 

 solidation, due to fibrinous exudation into the alveoli and 

 infundibula, the capillaries being distended by blood ; 

 haemorrhages occur in the peribronchial tissue with 

 numerous B. pestis. In the kidney the capillaries of the 

 glomeruli are distended by and filled with blood and B. 

 pestis ; the blood-vessels in the cortex next the boundary 

 layer are in many places surrounded by extravasated blood 

 with numerous B. pestis. The vessels of the Malpighian 

 pyramids are distended with blood, and some contain B. 

 pestis. Plague bacilli can be recognised in the space of 

 the Malpighian capsules, in the connective tissue around 

 the extravasated blood, and also in some of the uriniferous 

 tubules of the boundary layer. It is obvious that the 

 blood of the general circulation readily yields positive 

 result qud B. pestis on microscopic examination and in 

 culture. 



The intestine shows, both in its small and large divi- 

 sion, occasionally numerous punctiform haemorrhages, the 

 contents being bloody mucus ; such mucus, even on 

 microscopic examination, and, better, on culture and 

 experiment on animals, reveals the presence of B. pestis in 

 it. The spleen is literally packed with B. pestis ; it is 

 enlarged, and on section shows all parts of the pulp 

 permeated by continuous masses of B. pestis. The 

 number of B. pestis in the blood of the general circulation 

 after death is, in some cases, so great that their number is 

 not much inferior to that of the blood corpuscles. 



In the liver many interlobular capillaries show masses 

 of B. pestis ; the liver cells around them in some places are 

 full of fat globules, in other places they show coagulation 

 necrosis. In the suprarenals the blood-vessels are dis- 



