136 ORIENTAL PLAGUE chap. 



(5) Kidneys. — Great congestion of cortical vessels, in some 

 places haemorrhage; epithelium of convoluted tubes disintegrating. 

 B. pestis to be found only in large vessels amongst the blood 

 corpuscles. 



Rat lo. — (1) Bubo. — Almost complete necrosis due to infarct. 

 Masses of B. pestis in the cortical lymph sinuses and adjoining 

 cortical necrotic parts. 



(2) Spleen. — Infarct ; blood-vessels full of coagulated blood ; 

 Malpighian corpuscles shrunk and partially necrosed. B. pestis few, 

 chiefly in necrotic parts of Malpighian corpuscles. 



(3) Liver. — Infarct ; bacilli very sparse, if any. 



(4) Lung. — General congestion, some infundibula filled with 

 fibrin and leucocytes. B. pestis very sparse, if any. 



(5) Kidney. — Slight congestion, only larger vessels distended by 

 blood. B. pestis very sparse, if any. 



Rats 1q and In differed in no way from the previous rats, 

 except that the inguinal lymph glands showed extreme filling of 

 the cortical lymph sinuses with masses of B. pestis; so also the 

 lymph vessels around the glands were partially or wholly filled with 

 B. pestis. 



IV. — Mice inoculated cutaneously with B. pestis of Attenuated Type. 



There was no difference, in the condition of the organs and in 

 the wide and copious distribution in them of B. pestis, between mice 

 of this series and the mice described in reference to the virulent 

 series. The extreme prevalence of B. pestis in connected masses in 

 the lymph spaces and lymph sinuses of the bubo, in the spleen pulp, 

 in the vessels of the liver and lung, is a remarkable feature ; just as 

 conspicuous as that described of the mice in connection with the 

 virulent type of B. pestis. 



From this it appears that as regards the mouse both types of 

 plague act in the same manner j that for both types of plague bacilli 

 the tissues of the mouse offer a most excellent nidus for growth and 

 multiplication. But it is different with the rat. In this animal a 

 distinction between the two types can be made in view of the 

 result of the changes produced in the spleen and by the distribution 

 of the B. pestis in this organ, in the lung and liver, and in the blood 

 in general. 



In the attenuated type the spleen of the rat is in a large per- 



