344 PROTECTIVE INOCULATIONS. 



ticsemia, and if not identical with these at least varies from them so 

 slightly in its morphological and biological characters that recent 

 authors do not feel justified in considering it a distinct species. 

 Koch first obtained his bacillus of rabbit septicaemia by inoculating 

 rabbits with putrefying flesh infusion. Gaffky produced the same in- 

 fectious disease in rabbits by inoculating them with impure river water. 

 Davaine had previously obtained similar results by inoculating rabbits 

 with putrefying blood. The writer in 1887 produced the same disease 

 in rabbits, while in Cuba, by inoculating them with putrefying liver 

 from a yellow-fever cadaver. A similar, and possibly identical, ba- 

 cillus has been found in the blood of deer (Hueppe), of cattle (Kitt, 

 and of buffalo (Oreste-Armanni) suffering from a fatal infectious dis- 

 ease. And all of these allied species or varieties are included by 

 Hueppe and by the present writer under the single specific name 

 Bacillus septicwmice hcemorrhagicw. The bacillus of the disease known 

 in this country as swine plague, according to Smith, agrees in all par- 

 ticulars with that of the German swine plague (Sckweineseuche) de- 

 scribed by Loftier and Schiitz, except that the latter is more patho- 

 genic for swine and for rabbits. 



In a publication by Smith and Moore (United States Department 

 of Agriculture, Bureau of Animal Industry, Bulletin No. 6, 1894) they 

 have given an account of their experiments relating to immunizing 

 animals against the pathogenic action of this bacillus. The bacilli 

 used in these experiments were sufficiently virulent to kill rabbits in 

 twenty hours when injected beneath the skin of these animals in doses 

 of 0.001 cubic centimetre of a fresh bouillon culture. The experiments 

 were made upon young adult rabbits by various methods, viz. : with 

 sterilized bouillon cultures ; with sterilized suspensions of agar cul- 

 tures; with the filtrate of agar suspensions; with defibrinated, steril- 

 ized blood of infected rabbits ; "with blood serum from immune animals. 



"A greater or less degree of immunity was produced in rabbits by steril- 

 ized bouillon cultures, sterilized agar suspensions, sterilized blood from 

 infected rabbits, and blood serum from immunized rabbits. The sterilized 

 blood of diseased rabbits was capable of producing 1 immunity, while the 

 blood serum of immune rabbits produced rather equivocal results." 1 



The different degrees of immunity which may be acquired by 

 rabbits, as shown by a subsequent inoculation with virulent material, 

 are classified by Moore as follows : 



"1. No resistance acute septicaemia. 

 "2. Slight resistance peritonitis. 



"3. Increased resistance pleuritis and pericarditis with or without sec- 

 ondary pneumonia. 



"4. Higher degree of resistance pleuritis and peritonitis. 



