164 



BACTEEIOLOGY 



communicable. The experiments proved that these bacilli 

 are slender bristle -like rods, having circular spores at one 

 end and possessing but little power of automatic movement, 

 which very often range themselves in 

 chains or clumps (fig. 61). The tetanus 

 bacillus is rigidly anaerobic and occurs 

 very often in conjunction with other 

 anaerobes, so that the disease has been 

 supposed to be due to the united 

 action of several of these anaerobic 

 micro-organisms. This is described as 

 symbiosis. 



The bacilli stand a tolerably high tem- 

 perature about 80 C. without losing 

 their pathogenic power, but growth takes 

 place best at incubating heat. This 

 peculiarity, viz. that the spores can be 

 subjected to a high temperature without 

 losing their vitality, enabled Kitasato to 

 obtain pure cultures of the tetanus ba- 

 cillus, since the other bacilli cultivated 

 along with them are destroyed at a tem- 

 perature of 80 C., so that it is then not 

 difficult to procure a pure culture of the 

 tetanus bacilli, which remain alive. A 

 trace of pus from a patient suffering 

 from tetanus is smeared upon serum 

 solidified in the slanting position, or upon 

 agar, and the cultures so made are then 

 deposited in the incubator for some days. 

 They are next transferred for from half 

 an hour to an hour to a water- bath 

 heated to 80 C., in order to kill the rnicro- 

 pfeSer.) Fraenkel and organisms which have grown along with 



FIG. 62. ANAEROBIC GELA- 



