280 



BACILLI OF THE TYPHOID GROUP 



sick animals. The mortality varies from 30 to 100 per cent. ; in the 

 acute type the death rate exceeds 80 per cent, of the affected herd. 

 Morphology and Staining Properties. While evidently not the cause 

 of the disease, which can be transferred from sick to healthy hogs 

 by the filtered, bacteria-free blood, the Bacillus suisepticus is, never- 

 theless, in so close a relation with the affection as it occurs under 

 natural conditions that it must be studied in connection with it. The 

 bacillus is a plump, rather short rod, with rounded ends; it is from 

 1.2 to 1.8 micra long; in the tissues it occurs as single bacilli or in 

 chains of two, while in artificial culture media it often forms longer 



FIG. 141 



FIG. 142 



Bacillus of hog cholera. X 1000. 

 t__ ^(Author's preparation.) 



Bacillus of hog cholera, flagellar stain of 

 Pittfield. X 1000. Cover-glass prepared by 

 Dr. L. E. Day. 



chains, which, however, rarely grow as long as those often formed by 

 the typhoid bacillus. It is lively motile, and surrounding its body are 

 from three to nine long flagella. It stains with the ordinary watery 

 anilin stains, not so well with methylene blue, best with f uchsin. With 

 the latter it appears uniformly dyed, with the former the centre often 

 remains unstained. It is Gram negative. It does not form spores. 



Cultural and Biologic Properties. The organism grows at a wide 

 range of temperature, namely between 8 and 42 C., best at blood 

 temperature and in the presence or obsence of oxygen. It grows well 

 in slightly alkaline, less vigorously in slightly acid media. It ferments 

 glucose but not lactose or saccharose. It does not turn milk acid 

 and does not coagulate it. It does not form indol. On gelatin 

 plates round, bluish, transparent colonies are formed, and in gelatin 

 stick cultures a grayish-white streak develops. The medium sometimes 

 exhibits a milky cloudiness but is not liquefied. On cigar slants a 

 grayish-white glistening, not tenacious growth appears after twenty- 

 four hours' incubation. On coagulated blood serum the growth is 

 similar to that on agar. Nutrient bouillon becomes uniformly cloudy 



