vni AGGLUTINATION OF B. PESTIS 215 



derived from a case of bubonic plague that had occurred 

 in a sailor at LlandafF. The blood serum of the above 

 guinea-pig caused decided agglutination of both strains in 

 ten minutes, the control specimen of the salt emulsion 

 showing no alteration. 



The single injection, therefore, of living culture had 

 decidedly enhanced the agglutinating power of the blood 

 serum of this animal. 



(e) The further history of this animal is as follows : — 

 On April 22 it was reinoculated subcutaneously with one 

 loopful of living bacilli taken from a recent gelatine 

 culture ; it was further injected on May 2 and May 28 

 and June 17, each time with two to three loops of living 

 gelatine culture. On July 9 its blood serum was tested 

 (dilution 1 : 20) and found to produce complete-agglutina- 

 tion in about five minutes, certainly within ten minutes. 

 On same day (July 9) it was again injected with two to 

 three loops of living culture. Its blood serum was tested 

 (dilution 1 : 20) on July 16, and gave complete agglutina- 

 tion of plague emulsion in ten minutes. 



On July 18 the guinea-pig was further injected with 

 two to three loops of living culture. On July 29 its 

 blood serum was tested (dilution 1 : 20) ; result, no agglu- 

 tination in fifteen minutes, but distinct in forty minutes. 

 It was again injected on July 31. On August 9 its blood 

 serum produced no agglutination in thirty minutes. The 

 animal was reinjected on August 26. Its blood serum 

 was tested on September 10 ; no agglutination in thirty 

 minutes. Eeinjected on September 16. Blood serum 

 showed no agglutination on October 1, but gave distinct 

 and complete agglutination within ten minutes on 

 October 15 and on October 17. 



