MODIFICATIONS 



91 



First degree of resistance— peritoniti<;.—^2\i\y\\ No. 12 re- 

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

 ized by heat. vSubsequently with a control rabbit it was in- 

 oculated 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 a dilation of surrounding blood vessels. The 

 peritonitis was characterized by an exudate of a slightly viscid 

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

 fibrin, leucocytes and immense numbers of bacteria. 



Second degree of resistance — pleiiritis and pericarditis. — Rab- 

 bit No. 38 was treated before inoculation with 4.5 cc. of a 

 sterilized suspension of agar cultures of swine-plague bacteria 

 in 3 doses. Together with a control rabbit, it received under 

 the skin the equivalent of o.ooi cc. of a fresh bouillon culture 

 of swine-plague bacteria. The control died in twenty hours. 

 The treated rabbit died six days after inoculation. At the 

 point of inoculation there was a purulent infiltration of the sub- 

 cutis 3 cm. in diameter. The abdomen and abdominal viscera 

 were free from macroscopic changes. In the thorax, the pleural 

 cavity was lined with a grayish, friable exudate consisting of 

 round cells and bacteria. Lungs hyperemic and only partly 

 collapsed. Pericardium also covered with a slight exudate. 



Third degree of resistance — pleiiritis (^pericarditis) and peri- 

 tonitis. — Rabbit No. 15 received in the ear vein a total of 12 cc. 

 of a sterilized bouillon culture of swine-plague bacteria. It was 

 inoculated subcutaneously with virulent swine-plague bacteria 

 May 26, and died June 3, eight days later. The control rabbit 

 died within eighteen hours. The following changes were 

 observed : 



A purulent infiltration into the subcutaneous tissue at the point of 

 inoculation extending over an area 6 cm. in diameter. The superficial 

 layer of the subjacent muscle discolored. Surrounding the area of 

 infiltration the blood vessels were injected. The cecum and liver 

 were covered with a very thin grajnsh exudate, which also ap- 



