220 



ORIENTAL PLAGUE 



CHAP. 



The blood serum was tested (dilution 1 : 20) on the 

 following dates, with the following results : — 



These experiments are in accord with those in 

 which the blood after repeated injections acquired a 

 gradually increasing agglutinating power, and later on, 

 notwithstanding continued injection, again lost it. They, 

 moreover, tend to show that the intraperitoneal injection 

 of small doses of HafFkine's prophylactic into guinea- 

 pigs is more conducive to the formation of agglutinin 

 than the subcutaneous administration of doses twice as 

 large. 



II. — Experiments of Agglutination with Blood 

 of Babbits 



In this series rabbits were substituted for guinea-pigs, 

 and, as will be shown, the rabbit proved very much more 

 satisfactory. 



5. One half-grown rabbit, No. 1, was injected intra- 

 venously (ear vein) repeatedly with at first sterile and then 

 living plague culture : — 



