114 OMENTAL PLAGUE chap. 



The following experiments illustrate this : — 



Series A 



Experiment 1. — A rat (a) was injected cutaneously 

 with a three days old gelatine culture of " L.P. L" 



A second rat (b) was at the same time injected 

 with a three days old gelatine culture of the swollen 

 gland of one of the Haffkine protected rats just 

 referred to. 



In both cases, therefore, the B. pestis was originally 

 the same strain, viz. L.P. I. ; but, as just described, the 

 culture for rat (b) was derived from the gland of a 

 protected rat. 



Eat (a) died in less than three days : post mortem 

 there was a big bubo on the inoculated side crowded with 

 B. pestis ; the spleen was large, dark, full of B. pestis ; the 

 intestine was inflamed, containing sanguineous mucus ; 

 the heart's blood contained numerous B. pestis. 



Eat (b) had a big bubo on the inoculated side ; but 

 it remained lively and fed well up to the seventh day, 

 when it was killed. Post-mortem examination showed 

 the inguinal glands much enlarged, and necrotic in their 

 interior; few bacilli noticeable. The viscera, including 

 the spleen, appeared unaltered. 



Experiment 2. — One rat, 1a, was inoculated sub- 

 cutaneously with (a large dose) two loops of a four days 

 old agar subculture (second transfer) of the swollen gland 

 of the protected rat. This rat died on the fourth day. 

 On post - mortem examination it showed : big bubo, 

 crowded with short B. pestis; spleen enlarged and 

 containing some (bipolar) B. pestis ; intestine, liver, and 



