170 BACTERIA 



without a sign of injury anywhere. Sheep and goats are suscep- 

 tible to infection, so are guinea pigs and rabbits. Horses are 

 peculiarly susceptible. Soil, or manure, getting into wounds, is 

 often a cause of tetanus. Cow-dung poultices, mud dressings, or 

 cobweb applications to stop haemorrhages, 

 have also caused the disease. Tetanus 

 following vaccination is often due to infected 

 virus, the latter becoming infected from the 

 feces of the vaccine-producing cows but more 

 commonly is due to dirt getting into vacci- 

 nation wounds. 



sh 5 owtag et p^ Cultures.-This organism is difficult to 

 trichous flagella. (Kolle grow, and always requires an atmosphere of 

 and Wassermann.) hydrogen> 



On gelatine plates, the colonies appear first as minute white 

 specks, which slowly liquefy the medium. As it grows, hair-like 

 threads branch out into the medium, and the colony resembles the 

 periphery of a chestnut burr; later, the white appearance changes to 

 yellow. In gelatine stab the growth is, at first, whitish along the 

 line of the needle, eventually the gelatine becomes liquid, and a 

 bubble of gas, partly filled with whitish-cloudy liquid gelatine, 

 appears. On agar plates the colonies are ragged, and are sur- 

 rounded by delicate out-spreading filaments. In deep stab culture, 

 down in the agar and remote from the top, a spreading tree-like 

 form appears, with spike-like growths in the agar. Blood serum 

 is sometimes liquefied. Bouillon is uniformly clouded, gas is 

 generated if sugar is present, and toxin is produced. Milk is, 

 generally, not coagulated. 



All cultures of tetanus must be grown under an atmosphere of 

 hydrogen in media, from which all free oxygen has been driven 

 by boiling, or else abstracted by a mixture of pyrogallic acid and 

 sodium hydrate. It is possible to cultivate the organism under 

 mica covering, or paraffine poured upon freshly boiled media. If 

 sterile glass tubing is filled with agar or gelatine, and inoculated 



