vi PLAGUE INDUCED IN OTHER RODENTS 131 



lung — organs, that is, which are always found more or less congested ; 

 and only in few instances have I seen the intralobular capillary 

 blood-vessels of the liver containing groups and streaks of plague 

 bacilli. It follows, therefore, that the state of the blood-vessels 

 around the inguinal glands is entirely different from the state of the 

 blood-vessels obtaining in other organs ; and further, that this 

 peculiar state of the venous vessels around the gland — viz. their 

 containing large and small masses of B. pestis — is due to the B. pestis 

 being absorbed and carried from the seat of inoculation directly by 

 way of the veins. The cutaneous injury, above described, would no 

 doubt involve many superficial veins, and owing to the state of the 

 inguinal glands — viz. great swelling and necrosis — the circulation of 

 blood in them would become impeded. This in its turn would affect 

 and impede the circulation also of the surrounding tissue, hence in 

 many of them stasis of blood and multiplication of the B. pestis would 

 be the result. 



2. The next organ in importance is the spleen. This organ is 

 generally considerably enlarged, dark in colour, and firm; on a cut 

 being made into its substance no fluid (blood) oozes out. This latter 

 condition of the organ is in contrast with that in septicaemia and 

 other diseases in which, the spleen being large and dark owing to 

 hyperemia and active congestion, there is always a quantity of 

 blood oozing out from the spleen's cut surface. On examining 

 microscopic sections through the " plague spleen " such as is in question, 

 the blood-vessels and blood spaces of the pulp are found greatly 

 distended by blood which mostly is not in a fluid but in a clotted 

 state ; in fact, there is extensive infarct. In many instances there is 

 indication of necrosis and breaking down of pulp tissue of the spleen, 

 but only in small microscopic foci. As regards the distribution of 

 B. pestis in the spleen, these micro-organisms are found almost every- 

 where and in great abundance — in a scattered manner, but 

 particularly in smaller and larger connected masses, in streaks and 

 clumps in the blood-vessels (stasis), and in amongst the pulp tissue 

 in which breaking-down process is observed. On careful inspection 

 the streaks and clumps of B. pestis are seen to be really contained 

 within the blood spaces of the pulp tissue where this reaches an 

 extensive degree, as, for instance, in the necrotic nodules of the spleen 

 in the subacute form in guinea-pigs. The blood spaces show in places 

 an almost perfect natural injection with B. pestis. 



3. The lungs are greatly congested either uniformly through lobes 



