SWINE PI.AGUE 65 



Moore were able to produce nearly all the pathological variations 

 which follow the inoculation of natural races of swine-plague 

 bacteria as isolated from outbreaks. This modification of the 

 septicaemia type is not fortuitous, for among the large number 

 of rabbits inoculated during the past three and one-half years 

 with the culture employed, none have survived twenty to 

 twenty-four hours. Whenever the course of the inoculation 

 disease in rabbits departed from this rapidly fatal type, it was 

 due to some preliminary treatment of the rabbit. 



' 'The degree of resistance determined quite regularly though 

 not invariably the form of the disease. This degree was meas- 

 ured by the relative quantity of the protective material (steril- 

 ized cultures, sterilized blood, and blood serum) injected. The 

 grades of disease induced range themselves in the following 

 order : 



1. No resistance — acute septicaemia. 



2. Slight resistance — peritonitis. 



3. Increased resistance — pleuritis and pericarditis with or with- 



out secondary pneumonia. 



4. Higher degree of resistance— pleuritis and peritonitis. 



5. Still greater resistance— irregular lesions in the form of ab- 



scesses, subcutaneous and subperitoneal. 



6. Nearly complete immunity. Very slight reaction at the 



point of inoculation. 



Most of the cases cited below as illustrating these modified 

 forms of the septicaemia type belong to the series of immuniz- 

 ing experiments of the preceding article. To this the reader 

 is referred for additional illustrations. 



First degree of resistayice— peritonitis. — Rabbit No. 12 re- 

 ceived 7 cc. of bouillon culture of swine-plague bacteria steril- 

 ized by heat. Subsequently with a control rabbit it was inocu- 

 lated with a minute dose of swine-plague bacteria under the 

 skin. The control died within eighteen hours, the treated 

 rabbit in three days. The macroscopic changes were limited 

 to the point of inoculation and the peritoneum. At the former 

 there was a purulent infiltration of the subcutis, 1.5 cm. in 

 diameter, with dilatation of surrounding blood vessels. The 

 peritonitis was characterized by an exudate of a slightly viscid 

 character covering liver, spleen, and caecum, and made up of 

 fibrin, leucocytes, and immense numbers of bacteria. 



