Pathogenesis 



655 



of planting. If the bacteria be dispersed throughout the 

 culture medium, the little colonies appear in the lower parts 

 of the tube as nearly spheric or slightly irregular, clouded, 

 liquefied areas containing bubbles of gas. If, on the other 

 hand, the inoculation be made by a deep puncture, a stock- 

 ing-shaped liquefaction forms along the whole lower part of 

 the puncture, with considerable gas-production, and finally 

 causes the liquefaction of all the gelatin except a thin super- 

 ficial stratum. A peculiar acid 

 odor is given off by the cul- 

 tures. 



Agar-agar. In agar-agar the 

 development is similar to that 

 in gelatin. The gas-production 

 is marked, the liquefaction of 

 course absent, and the same acid 

 odor pronounced. 



Bouillon. The bacillus also 

 develops quite well in bouillon, 

 the bacillary masses sinking to 

 the bottom in the form of 

 whitish flakes, while the gas 

 bubbles collect at the top. In 

 this medium the virulence is un- 

 fortunately soon lost. 



Milk. The development of 

 the bacilli in milk is unaccom- 

 panied by coagulation. 



Pathogenesis. When suscep- 

 tible animals are inoculated with 

 a minute portion of a pure cul- 

 ture, the bacilli grow and pro- 

 duce the well-known affection, 

 with its fatal outcome. Cattle 

 seem to be the most susceptible 

 animals, especially when between 

 six months and four years old; 



sheep and goats are also sometimes affected. Curiously 

 enough, animals that are immune against malignant edema 

 seem to be more susceptible than others to " Rausch- 

 brand." Of the laboratory animals, the guinea-pig is most 

 susceptible ; swine, dogs, and rabbits are slightly suscepti- 

 ble; horses, goats, and birds are immune. 



Fig. 196. Bacillus of 

 symptomatic anthrax; four- 

 days-old culture in glucose 

 gelatin (Frankeland Pfeiffer). 



