352 INFECTIVE DISEASES. 



Billings appears to have isolated two bacilli, one identical with 

 the Marseilles bacillus, and the other with the hog-cholera bacillus. 



Bacillus of Rietsch and Jobert. — Rods about twice as 

 long as broad, rather shorter than the bacillus of typhoid fever, 

 longer and thicker than the American, bacillus. They exhibit 

 end-staining. They possess flagella, and are actively motile. 



They grow rapidly in nutrient media. They are only feebly 

 pathogenic. They are also said to be distinguished from the bacilli 

 of hog-cholera by producing indol in solutions containing peptone, 

 and by causing an acid reaction in milk. 



Bacillus of M'Fadyean. — ^M'Fadyean investigated swine fever 

 in 1895, and found bacilli which he differentiated from hog-cholera 

 bacUli. The method employed was to inoculate the surface of 

 nutrient agar and of potato, with fragments torn out of the centre 

 of a lymphatic gland, with specially constructed forceps. Inocula- 

 tions were also made from the spleen pulp, and blqod, in the usual 

 way. They are from 1 to 2 //. in length, and •& fj, in breadth. 

 They never grow into filaments, they do not form spores, and 

 they are actively motile. They are readily stained by the watery 

 solutions of the aniline dyes, and are decolorised by Gram's 

 method ; with methylene-blue they show end-staining. The bacilli 

 grow on gelatine without liquefaction, forming a thin white line 

 along the needle track. On agar a thin, transparent pelUcle forms, 

 which is not easily visible at first, but gradually acquires a faint 

 greyish tint. More characteristic appearances result in plate- 

 cultivations of gelatine-agar, at 37° C. The colonies are distinctly 

 visible in eighteen hours, appearing when viewed by transmitted 

 light as bluish-wliite, circular specks ; each colony has a dark centre 

 and a granular margin. In broth the bacilli produce turbidity after 

 twenty-four hours. On potato there is no visible growth, even when 

 the surface is inoculated with an abundance of material. On sohd 

 blood serum the growth is scanty. They grow in milk without 

 producing coagulation. They are harmless to guinea-pigs and feebly 

 pathogenic to rabbits. 



Several experiments were carried out upon swine. In the first, 

 series the most rigid precautions were taken to prevent accidental 

 infection with swine fever. Four young pigs were inoculated, upon 

 a farm where there was no previous history of the disease. These 

 pigs were killed, and the post-mortem examinations were said to 

 show indications of swine fever, principally patches of diphtheritic, 

 material in the colon, and healing ulcers. The next series of pigs 

 was inoculated at the Royal Veterinary College. Cultures were 



