ix PEOTECTIVE INOCULATION 259 



a little more active in temporarily raising the body temperature 

 (1-5° F. in rabbit No. 7, 0*8° F. in rabbit No. 8); but here also 

 the rise is not sufficiently striking to warrant assumption of any 

 specific action. It is possible that the effect of injecting sub- 

 cutaneously 20 cc. of any fluid containing in solution chemical 

 substances of various composition, such as naturally result from 

 the long-continued (four to six weeks) growth of bacteria in broth, 

 would be similar as regards temperature. However this may be, it is 

 certain that the blood of these animals did not contain agglutinating 

 substances even after the fourth injection of 20 cc. of the filtrate. 



Observations as to Protection against Plague 

 Infection conferred on Animals by previous 

 Injection of Haffkine Plague Prophylactic. 



A. — Guinea-pigs. 



From the experiments recorded in Chapter VIII. it will 

 have been obvious that repeated injection of the dead (i.e. 

 sterilised) bacilli taken from the surface of solid media 

 confers on the guinea-pigs and rabbits a certain degree of 

 immunity. The subsequent injection of living culture of 

 B. pestis did not cause a fatal issue. But as in 1896-1897, 

 so also now, the immunity thus conferred on the guinea- 

 pig, viz. by this injection of sterilised bacilli, was not of 

 a high order, since on each subsequent subcutaneous 

 injection of living culture the animals reacted, as shown 

 by the development of a bubo on the inoculated side, 

 which bubo soon, however, suppurated and healed up. 

 I have at present in the laboratory a guinea-pig which 

 exactly a year ago, May 6, was injected the first time 

 with the growth scraped from the whole surface (6 

 centimetres by 2 centimetres) of a gelatine culture of 

 B. pestis. The growth was sterilised as a salt emulsion 



