vii INFECTION OF ANIMALS WITH PLAGUE 175 



the materials were found quite dry and extremely hard 

 and brittle. They were now given as food to two white 

 mice, Nos. 5 and 6 (rice plague organs), and to three 

 wild mice, Nos. 7, 8, and 9 (wheat plague organs). The 

 animals ate all the food within twenty-four hours. One 

 of the white mice was found dead on June 16. It had 

 extensive skin disease and a big worm in the liver, but its 

 intestine and spleen were not affected. The other white 

 mouse and the three wild mice remained alive and un- 

 affected. From this it would seem that the material had 

 been dried too much, and that probably all plague bacilli 

 in them had been killed. 



Experiment 9. — This experiment was made in repeti- 

 tion of experiment 3. Wheat and rice were mixed with 

 old gelatine cultures of B. pestis (derived from blood and 

 spleen of rats and mice dead of plague after feeding), and 

 the mixed materials dried over sulphuric acid for twenty- 

 four hours. The materials were then, June 21, given to 

 rats, two for each lot. One of the rats, No. 14, fed with 

 wheat gelatine culture was found dead in the morning of 

 June 25 ; the companion, No. 15, pregnant, was very 

 ill and was killed. On post-mortem examination this 

 animal (15) contained seven dead foetuses, nearly full 

 time ; there was a great deal of peritonitis ; the spleen 

 was small and had no plague bacilli ; there was no appear- 

 ance of plague. 



But the post-mortem examination of rat No. 17 

 showed lesions in the ileum and Peyer's glands, mesenteric 

 glands, and spleen, identical with those already described. 

 It is not necessary, therefore, to further refer to them 

 beyond saying that film specimens and cultures of the 

 hemorrhagic mesenteric glands, of the spleen, and of the 



