270 BACILLUS OF TETANUS 



possess numerous peritrichous flagella, estimated from thirty to fifty 

 and even up to one hundred. Spore formation in cultures kept 

 anaerobically in the incubator occurs after twenty-four to thirty hours; 

 at room temperature in gelatin tubes after eight to ten days. The 

 most abundant sporulation occurs in sugar free bouillon and on 

 blood serum. The tetanus bacillus forms its spore at one end, it is 

 round and much larger in diameter than the vegetative form of the 

 bacillus, namely, 1 to 1.5 micra. A sporulating bacillus somewhat 

 resembles a drum stick and for this reason, the microorganism is also 

 called the drum stick bacillus of tetanus. When the culture medium 

 contains sugar or glycerin the spores are sometimes oval and not 

 perfectly spherical. 



The tetanus bacillus stains with the ordinary watery anilin stains 

 and is Gram positive. The spores and the flagella can only be stained 

 by special methods. 



Anaerobic Methods. The bacillus is anaerobic and does not grow in 

 the presence of oxygen. A variety of methods are used to exclude 

 the atmospheric air. The cultures may be kept in an air-tight jar 

 in which the common air has been replaced by hydrogen or in a jar 

 in which the oxygen has been absorbed by pyrogallic acid and 

 caustic soda solution. The bacillus may also be raised in a bouillon 

 from which the air has been expelled by prolonged recent boiling and 

 the surface of which has been covered by oil or butter, or in gelatin 

 stick cultures, which after inoculation are covered by a high layer 

 of gelatin containing some glucose. 



Cultural Properties. On gelatin plates kept at 20 C. (room 

 temperature) colonies of the tetanus bacillus become visible on the 

 third day. The small young colonies under a low magnification show 

 a central solid area surrounded by radiating cords, bands or filaments. 

 The young colonies somewhat resemble those of the Bacillus proteus; 

 at other times they appear more like those of the Bacillus subtilis. In 

 a gelatin stick culture the growth begins about one-half inch below 

 the surface and proceeds downward, forming at the same time lateral 

 projections which appear more or less cloudy. After the tenth day 

 the gelatin becomes more and more liquefied, and simultaneously a 

 very fetid gas is formed. On agar the growth is similar but there is 

 no liquefaction. In bouillon kept at 39 C. there is a very rapid growth 

 with marked clouding and the appearance of fine gas bubbles. 

 Sedimentation begins to show on the fifteenth day. The gases formed 

 are carbon dioxide and ethane and methane gas. During their 

 formation the alkalinity of the fluid increases, provided no sugar is 

 present. The tetanus bacillus does not grow at temperatures below 

 14 C.; at 18 to 20 C. the growth is slow and easily visible to the 

 naked eye only after one week; at 20 to 25 C. a good growth develops 

 in three to four days; the organism grows best at 36 to 39 C. 



Tetanus Bacilli and Aerobic Bacteria. The tetanus bacillus when 

 grown in artificial pure cultures is, as has been stated, strictly anaerobic 



