ix PKOTECTIVE INOCULATION 261 



produce results more favourable than the repeated in- 

 jection of living plague bacilli. In 1899-1900, with 

 Professor Haffkine, at the instance of the Local Govern- 

 ment Board, I made a number of experiments with 

 the Haffkine plague prophylactic. In these a series 

 of guinea-pigs received by a single subcutaneous in- 

 jection various amounts of the plague prophylactic — 

 5 cc, 10 cc, 30 cc, 40 cc, and even 60 cc. They 

 were subsequently injected with lethal dose of living 

 plague bacilli, as were, at the same time, a similar series 

 of control guinea-pigs. The result was this: — Of the 

 eight control guinea-pigs all died of plague. Of the 

 eight prepared guinea-pigs seven died of plague ; in the 

 eighth animal the bubo suppurated and ultimately healed. 

 During later experiments several guinea-pigs were, as 

 mentioned in a previous chapter, repeatedly (as often 

 as eight times) injected (subcutaneously and intraperi- 

 toneally) with Haffkine prophylactic, and afterwards with 

 living culture. They developed typical bubo. I have at 

 present a guinea-pig which had been injected eight times 

 intraperitoneally with Haffkine prophylactic between 

 June 17 and October 21, receiving altogether 51 cc. of 

 the fluid. On December 28 it was injected subcutane- 

 ously with small dose of living culture of B. pestis. It 

 developed typical bubo. On May 5 of this year it 

 was again injected with an ordinary lethal dose. It 

 remained alive, but by the end of the week it had a bubo 

 of the size of a pigeon's egg. 



The same negative results were obtained by injecting 

 guinea-pigs with the clear filtrate of Haffkine's prophy- 

 lactic ; and it is not necessary to detail them beyond 

 noting that neither the subcutaneous nor the intraperi- 



