PATHOGENIC BACTERIA. 269 



mice, pigeons and various other animals, including man. 

 Inoculation results in the production of swelling and edema, 

 spreading from the point of inoculation. Gas may be pro- 

 duced in the tissue. It may lead to wide-spread septicemia. 

 Bacillus tetani. — ^A sHm, straight bacillus, with rounded 

 ends, which may form in threads. It is sKghtly motile. Spores 

 form in culture-media at the end of thirty hours in the in- 

 cubator. The spores are located at one end, which is 



.- '< 





:u ": 



Fig. 74. — Tetanus bacilli, showing Spores. (X 1000.) 



swollen, so that in this stage the organism has the shape 

 of a drum-stick. The spores are extremely resistant, and 

 in the dry condition remain capable of germinating under 

 favorable conditions for years. They are killed by moist 

 heat at ioo° C. in five minutes; by 5 per cent, carbolic acid, 

 in fifteen hours; by bichloride of mercury, i-iooo, in three 

 hours. The tetanus bacillus stains by Gram's method. It 

 is a strict anaerobe; it grows in an atmosphere of hydrogen, but 

 not of carbon dioxide. It may sometimes be made to grow 



