vi PLAGUE INDUCED IN OTHER RODENTS 133 



vessels of the mucosa are distended and filled with blood, with 

 capillary haemorrhages into the tissue ; the epithelium of the surface 

 is detached and wanting in many parts, and here the tissue of the 

 mucosa is breaking down ; the epithelium lining the crypts of 

 Lieberkiihn is detached and disintegrating. Plague bacilli are found 

 in great numbers and masses in the superficial parts of the broken- 

 down mucosa ; where this is denuded of its epithelium there may be 

 a continuous layer of these bacilli, all showing beautiful bipolar 

 staining. It is clear, therefore, that the bowel discharges of such an 

 animal would be containing plenty of B. pestis. 



From these descriptions it is seen that in the acute and typical 

 form of plague such as in rats follows the cutaneous inoculation of 

 small doses of virulent B. pestis the changes in the different organs 

 are generally severe and very pronounced, and that the distribution 

 and multiplication of the B. pestis in these organs is of a very intensive 

 nature. 



II. — Mice inoculated cutaneously with the Virulent Type of B. pestis 



The conditions of the organs in the mouse are of a character 

 which may briefly be described as an exaggeration in intensity of 

 those observed in like circumstances in the rat. In all organs dis- 

 tension of the blood-vessels with haemorrhages is a dominant feature ; 

 and besides, the inguinal lymph glands and the spleen may be said 

 to be practically crowded with masses of B. pestis, which are in all 

 parts in continuous masses and in some places may almost entirely 

 obscure the tissue. 



1. The inguinal glands corresponding to the inoculated side, the 

 cortical as well as the medullary lymph sinuses, are practically 

 injected with B. pestis. Also in the lymphatic tissue of the cortex 

 and medulla masses of B. pestis can be seen everywhere. What is left 

 of the lymph tissue is necrotic in many parts. Not only the lymph 

 vessels and lymph spaces of the gland itself, but those also of the 

 surrounding tissue, show distension and almost complete injection 

 with B. pestis. 



2. In the spleen pulp there exists a continuous network of streaks 

 and irregular masses of plague bacilli, the blood-vessels of the pulp 

 being greatly distended and filled with blood. 



3. The lungs show uniform distension and filling of blood-vessels 

 with blood ; in many places within them are found continuous masses 



