262 OMENTAL PLAGUE chap. 



toneal injection of 10 cc. in each instance of this clear 

 nitrate on three separate occasions (within six weeks) 

 had any influence in inhibiting the ordinary results of 

 subsequent injection of small and large doses of living 

 B. pestis. 



B. — Babbits. 



The experiments made in conjunction with Professor 

 Haffkine on rabbits, although numerous, were on the 

 whole of an unsatisfactory nature, mainly because of the 

 difficulty and uncertainty in ascertaining what is a normal 

 fatal dose of plague culture for the rabbit. A large series 

 of rabbits were carefully noted as to body temperature 

 and body weight, before and after injection, with varying 

 amounts of the prophylactic (10 cc. to 34 cc). Control 

 rabbits, equally carefully noted as to body weight, were 

 kept separate, but corresponded as nearly as possible in 

 body weight to the prepared rabbits. In due time each 

 animal in both sets was injected with what ought to have 

 been a fatal dose of living plague culture. The result was 

 disappointing, because an equal proportion of prepared 

 rabbits and control rabbits succumbed to plague. 1 The 

 percentage of deaths in each class of rabbit was, however, 

 less than 50, whereas in the case of both guinea-pigs and 

 rats (used as controls) a fatal issue can always be ensured. 



The experiments which I have made in the course of 

 the present year on rabbits with sterilised solid plague 

 culture, with Haffkine prophylactic, and with the filtrate 

 of the prophylactic, were of an equally unsatisfactory 

 nature, and for the same reason, viz. unless extra large 



1 I note with surprise the statement by Professor Balfour Stewart ( Tkompson- 

 Yates Laboratory, vol. ii. p. 19) that he found 2 cc. of the Haffkine prophylactic 

 sufficient to immunise a rabbit of 1400 grammes body weight. 



