246 OMENTAL PLAGUE chap. 



and until the immunity it confers is established — that is to 

 say, during eight to ten days after the vaccinal injection 

 (as always exists after active immunisation by living 

 microbes or by their toxins) — the organism is, for the time 

 being, sensitive to an infection even very slight." 1 



Experiments which I have made on rats with my 

 organ prophylactic (see later) show, however, that these 

 animals do not show any increased susceptibility to plague 

 when injected with my organ prophylactic, even when the 

 testing with B. pestis is made as early as two to four 

 days after the injection of the prophylactic. Eats tested 

 six days after the injection of the prophylactic were fully 

 protected against an otherwise fatal dose of B. pestis 

 inoculated cutaneously. 



Haffkine himself admitted that owing to the stress of 

 circumstances (the demand for the fluid in India alone 

 was, owing to the spread of the plague, enormous) a great 

 many points concerning the precise nature and the best 

 method of employment of the fluid remained still un- 

 solved. For instance, the Plague Commissioners justly 

 point out that, from the evidence brought before them, 

 there does not seem to be any advantage in reinjection 

 of the same individual, provided the dose in the first 

 instance has produced the anticipated physiological action. 

 Further, as the Commissioners justly observe, there is as 

 yet a great deal of uncertainty as to the dosage for each 

 injection. Haffkine states, provisionally, that the dose 

 for a human being should be such as to cause, a few 

 hours after subcutaneous injection, a rise of temperature 

 of at least 2-3 degrees Fahrenheit. But the determination 

 of the dose on these lines would on a priori grounds 



1 Annates de Vlnstitut Pasteur, No. 12, 1899. 



