vii INFECTION OF ANIMALS WITH PLAGUE 179 



Similarly I am inferring that the negative results of feed- 

 ing with fresh materials are due to all the ingested plague 

 bacilli becoming readily exposed to the action of the gastric 

 juice, so that no living plague bacilli are capable of reach- 

 ing the ileum, and that the animal therefore escapes. 



It must be obvious from the above description that 

 the discharges of the intestine and the secretion of the 

 kidney in animals (rats, mice, or guinea-pigs) affected with 

 plague by feeding, in all probability contain abundance of 

 plague bacilli. It has been seen that the materials within 

 the cavity of the ileum of such animals swarm with B. 



necrotic nodules crowded with the B. pestis ; that is to say, the animal presented 

 the appearance of subacute plague which follows the cutaneous inoculation. 

 But in addition a portion of the lower ileum of this guinea-pig showed great 

 haemorrhage with a blood -clot in its cavity firmly adhering to the mucous 

 membrane, while the mesenteric glands were enlarged and showed haemorrhages ; 

 there were haemorrhages also — besides those mentioned — in the subcutaneous 

 tissue surrounding the inguinal bubo, also in the testis and omentum. Sections 

 were made of the haemorrhagic portion of the ileum and of the mesenteric 

 glands. These showed : (a) in the ileum and firmly adhering to the mucosa 

 (villi) a mass of blood, in which were large numbers of nests of B. pestis ; the 

 tissue of the villi was full of B. pestis, forming reticulated masses, as described 

 and figured of former cases, in which infection had started from the intestine ; 

 the central chyle vessel, as also the lymph vessels of the mucosa, were literally 

 crowded and injected with B. pestis, as were also the lymph vessels of the sub- 

 mucosa and of the outer muscular coat ; in the mesenteric margin of this part 

 of the intestine the efferent chyle vessels were distended and filled with blood and 

 with masses of B. pestis ; the large blood-vessels of the same parts were also 

 filled with blood, amongst which some B. pestis could be recognised, (b) The 

 mesenteric glands showed the same appearances as were described on a former 

 page, viz. the afferent and efferent lymph vessels were distended and filled with 

 B. pestis, so also were the cortical and medullary lymph sinuses ; a great deal of 

 haemorrhage was noticeable in the cortical lymph follicles. 



The appearances above described appear to me to admit of one interpretation 

 only, viz. this : in the ileum haemorrhage had taken place, witness the presence 

 of a blood-clot in the cavity ; the B. pestis in this clot being in a suitable place — 

 the ileum— had multiplied and had become readily absorbed by the villi in which 

 indeed they abounded ; the same process had followed in all the absorbents 

 of the intestinal wall and mesenteric glands. This was evidently made possible 

 by the duration of the disease (six days). So that a direct lodgment of B. pestis 

 in the intestinal cavity having occurred while the animal continued to live, time 

 was given for a secondary infection of this part of the ileum of the same character 

 as that observed in the other cases in which the B. pestis had reached the ileum 

 by way of the food. 



