olO REPORT OF THE COMMISSIONER OF AGRICULTURE. 



The bacterium of swine plajrne has beeu fully described in the pre* 

 cediiiff pages as to su'ch ])roperties which have beeu studied. It is a 

 motile bacterium, found chiefly in pairs. Each individual resembles an 

 elongated oval about twice as long as broad, the length being about 

 1.2'" to 1.5™. It is quite easily stained by the aniline colors. J t grows 

 readily in neutral, slightly alkaline, or acid infusions of meat, with or 

 without peptone; more slowly in nutritive gelatine which it does not 

 ''.quefy.- It grows very well on boiled potato and blood serum, as well 

 lis in milk. It varies somewhat in size when grown in different media. 

 It is killed in liquid cultures by being exposed to a temperature of 58° 

 0. for ten minutes. Spores are probably not formed. The effect of 

 [)rolonged drying has not yet been determined. 



Of six pigs inoculated subcutaneously with pure liquid cultures of 

 this bacterium, all'died of swine plague. In four of these animals the 

 same bacterium, which had been introduced into the system, was ob- 

 tained in cultures from the spleen and heart's blood. The indeutity of 

 the microbe from the different animals was determined microscopically 

 by culture methods and inoculations. Of four pigs fed with pure liquid 

 cultures two contracted the disease in a very severe form. Of the re- 

 maining two one had failed to take the disease when exposed before; 

 the other was sick for a time but recovered. In those fed, the intestines 

 were most severely diseased ; in those inoculated hypoderraically there 

 was in most cases a hemorrhagic inflammation of the kidneys. 



A number of pigs were fed with the viscera of those which had died 

 of swine plague. They all contracted a rapidly fatal form of the disease, 

 and the same bacterium was found in the spleen and blood of these 

 aniuials which had been obtained from the organs which they had con- 

 sumed. 



Mice pfoved quite susceptible to this bacterium. In at least twenty 

 which died from inoculation the oval motile bacterium was found. 

 There is usually some local reaction at the place of inoculation, mani- 

 fested by a whitish appearance and a soft, friable condition of the tis- 

 sues involved. A very frequent lesion is the great, at times enormous, 

 enlargement of the spleen, and the enlargement of the glands in the 

 knee fold. Less frequently the medullary portion of the kidneys and 

 the lungs are found deeply reddened. When bits of spleen from swine 

 were placed under the skin of the back, the disease lasted from eight 

 to sixteen days ; when cultures were injected, from live to eight days. 

 This diiierence is, without doubt, due to the difference in the number 

 of bacteria introduced into the system. In some of the animals in 

 w^hich the disease was prolonged bacteria vrere present in but small 

 numbers. This may be explained by regarding the animal as having 

 almost overcome the disease. In such cases, moreover, the spleen was 

 exceedingly large, indicating a slow but constant irritation leading to 

 hypertroi)hy. Only a very small proportion of the animals inoculated 

 with bits of spleen survived, while the cultures were invariably fatal. 

 In a large proportion of cases the bacterium was found in the spleen, 

 liver, kidneys, blood from the heart, and lungs. 



lu the one rahbit at our disposal death occurred about four daj'S after 

 inoculation with the pure culture. The bacterium was shown present 

 in the various internal organs by the microscope and cultures. The 

 only marked lesions were a great enlargement and congestion of the 

 spleen and hemorrhage in the stomach. In two guinea-pigs the virus 

 caused death in three to four days. The chief lesions were an extrava- 

 sation and infiltration of blood in the connective and muscular tissue 

 about the place of inoculation, slowly invading the rest of the body. 



