i THE ESSENTIAL CAUSE 11 



Sections were made and stained ; examined under the 

 microscope the hepatised portions showed uniform and 

 dense infiltration with leucocytes and red blood corpuscles, 

 the alveolar septa indistinct, the infundibula and bronchi 

 distended by and filled with red blood corpuscles, leuco- 

 cytes, and fibrin. Everywhere in these parts the walls of 

 the infundibula, bronchi, and alveoli were indistinct and 

 more or less broken, and everywhere between the blood 

 corpuscles and leucocytes there were B. pestis in con- 

 tinuous streaks, so much so that they filled all spaces left 

 by the cells ; some of the bronchioles were plugged with 

 continuous masses of B. pestis. Haemorrhage was present 

 in the peribronchial tissue. 



The rusty haemorrhagic sputum of cases of plague 

 pneumonia during life is described, by some observers, as 

 showing, besides numerous normal bipolar plague bacilli, 

 also some spindle-shaped and other swollen involution 

 forms. I have not come across these either in the lung 

 juice or lung sections of the above two cases, nor in the 

 bronchial contents of the affected lungs of animals which 

 had died of subacute plague, in which the lungs showed 

 larger or smaller, more or less necrotic patches, or were 

 in the condition of red hepatisation ; whether these spindle 

 forms occur naturally in the sputum or are artefacts, made 

 when preparing the film specimens, I am unable to say. I 

 have paid particular attention to this point in connection 

 with the exudation which is invariably present in the 

 larynx, trachea, and bronchi of animals (guinea-pigs and 

 rats) which are affected with subacute plague, and in 

 which the lungs are the seat of severe inflammation and 

 necrosis (pneumonic plague), but I have not been able to 

 meet with these spindle forms, and, as mentioned above, I 



