vii INFECTION OF ANIMALS WITH PLAGUE 177 



pestis. The mesenteric glands were necrotic, the lymph- 

 atics here being filled and distended with masses of B. 

 pestis. 



The two other white mice remained alive. 



In a number of other experiments old gelatine cultures 

 of plague bacillus or actual particles of plague organs were 

 mixed with wheat, rice, and flour, and were then left over 

 sulphuric acid for more than three days. As a result the 

 materials became thoroughly dry ; too dry, in fact, as 

 negative result of feeding rats and mice with them showed 

 — the animals remaining unaffected. More than forty- 

 eight hours drying over sulphuric acid appears to preclude 

 expectation of B. pestis remaining present in the material 

 in a living state. 



From these experiments it appears : — 



(1) That irats, mice, and guinea-pigs are capable of 

 infection with plague by feeding them with old 1 and 

 drying gelatine cultures alone ; with old gelatine cultures 

 mixed with wheat or rice and well dried previously ; and 

 with pieces of plague organs mixed with wheat or rice or 

 flour and dried previously. 



(2) That of animals thus fed a considerable percentage 

 become infected ; that the infection takes place in the 

 ileum at or about the Peyer's glands ; and that the in- 

 fected animals die between the fourth and sixth days. 



(3) That haemorrhage with great multiplication of 

 plague bacilli occurs in the ileum at the point of infection, 

 and this not only in the cavity of the intestine and on the 

 free surface of the mucous membrane, but also within the 

 villi themselves, in the absorbents of the villi and of all 



1 By old I do not mean gelatine cultures which are practically dead and have 

 lost all virulence, but gelatine cultures from two weeks to two months old and 

 which yield active and living subcultures. 



N 



