Etiology. 173 



aniline dyes as well as by Gram's method. On artificial media, 

 it grows in the same way as the streptococcus of strangles 

 (see that disease). 



Pathogenicity. Cultures kill mice in two to three days, 

 while rabbits are less susceptible, guinea pigs show a con- 

 siderable resistance against the infection. In the experiments 

 of Schiitz 4 cc. of a bouillon culture injected in various parts 

 of the lungs of a horse produced a gangrenous pneumonia and 

 a sero-fibrinous pleurisy which extended from the point of 

 inoculation. On autopsy great numbers of cocci identical with 

 those inoculated were found in the gangrenous areas and in 

 the tissues surrounding them, as w^ell as in the pleural exudate. 

 They were present in smaller numbers in the spleen and in 

 the kidneys. The inhalation of a sprayed culture produced 

 in the horse a circumscribed, chronic inflammation in one lobe 

 of the lungs. 



According to Lignieres the streptococcus in question is identical with the diplo- 

 eoccus of contagious pneumonia of Schiitz, with the streptococcus of Delamotte & 

 Chantemesse, as well as with the streptococcus of Violet & Galtier, and is closely 

 related to the streptococcus of strangles. 



II. The bacillus (bipolaris) equisepticus (Pasteurella equi), 

 which is considered by Lignieres and even before him by Babes, 

 as the true cause of the disease, represents a variety of the 

 bacillus bipolaris septicus of the hemorrhagic septicemia. In 

 regard to its staining and culture characteristics it is identical 

 with the other varieties of this bacillus (see page 79). 



Pathogenicity. Cultures obtained from the affected body 

 of a horse produced a severe pathogenic action on rabbits and 

 guinea pigs. The former succumbed to an intravenous in- 

 fection in 18 to 24 hours, while the latter died in the same 

 length of time from an intraperitoneal infection. Carnivorous 

 animals and sheep also die of septicemia following an intra- 

 venous injection. Subcutaneous injection of 0.25 cc. of culture 

 produces in the horse fever and a local inflammatory edema 

 which later changes to suppuration. Sometimes however such 

 an infection causes the death of the animal inside of four days. 

 The abdominal exudate of guinea pigs which die as the result 

 of an intraperitoneal infection acts much more severely. One- 

 quarter to one-fifth cc. of such exudate, when injected sub- 

 cutaneously into a horse may cause the death of the animal 

 in 24 to 48 hours, while 1 to 2 cc. injected intravenously kills 

 the animal in a few hours. In such cases the horse manifests 

 high fever, great debility, accelerated and small pulse, throbbing 

 heart action, muscular trembling, diarrhea, injection of the 

 conjunctiva, and lachrymation. Less severe infection produces 

 an edematous swelling of the extremities, and in some of the 

 joints a sero-fibrinous inflammation. Subcutaneous injections 

 of culture are sometimes followed by sero-fibrinous pleurisy, 



