v PLAGUE IN THE RAT 107 



interlobular connective tissue as well as the liver cells of 

 the acini. The lungs both in the rat and in the guinea- 

 pig, besides showing petechise, are also permeated by few 

 or many grey consolidations (some small and more or less 

 circumscribed, others large and irregular), the surrounding 

 lobules being much congested and showing more or less 

 red hepatisation. In the lung, both in the red hepatised 

 parts as also in the grey patches, vast numbers of B. pestis 

 can be demonstrated. Sections through the diseased 

 parts show the bronchi, infundibula, and alveoli distended 

 by and filled with fibrinous exudation — red and white 

 cells and continuous masses of B. pestis. Figs. 16 

 and 17 show this condition well. Fig. 16 is from a 

 section of the lung of a rat showing extensive grey 

 hepatisation. This rat (I) had died nine days after 

 cutaneous inoculation with the sanguineous mucus of the 

 intestine of a previous plague-infected rat (k). The muco- 

 purulent matter which was found, on careful dissection 

 and opening, in the pharyngeal cavity of the rat (I), was 

 inoculated cutaneously into a rat (m). Rat (m) developed 

 the typical inguinal bubo and died in three days of 

 plague. A film specimen of this inguinal bubo of 

 rat (m) is shown in Fig. 6. I shall return later to the 

 application of these observations ; at present I am content 

 to record them, and to add that the muco-purulent matter 

 that was present in the oral and pharyngeal cavity of the 

 rat (I) was examined by stained film specimens and by 

 culture, and that the abundant presence in it of typical 

 B. pestis was in this way demonstrated. Looking at 

 Fig. 17, which represents a section through a bronchus, 

 it will be readily understood how it comes that the oral 

 and pharyngeal mucus of this animal contained B. pestis 



