ISOLATION OF THE BACILLUS 



431 



wounds in tetanus, occurring naturally or experimentally pro- 

 duced, it has been isolated by means of the methods appropriate 

 for anaerobic bacteria. The best methods for dealing with such 

 pus are as follows : 



(1) The principle is to take advantage of the resistance of 

 the spores of the bacillus to heat. A sloped tube of inspis- 

 sated serum or a deep tube of glucose agar is inoculated and 

 incubated anaerobically at 37 C. for forty-eight hours, at the 



' FIG. 125. Tetanus bacilli, showing flagella. 



Stained by Rd. Muir's method, x 1000. 



end of which time numerous spore-bearing bacilli can often 

 be observed microscopically. The culture is then kept at 80 C. 

 for from three-quarters to one hour, with the view of killing all 

 organisms except those which have spored. From such material 

 agar anaerobic plates are prepared by one of the methods de- 

 scribed on pp. 37, 38. Kitasato compares the colonies in gelatin 

 plates to those of the b. subtilis. They consist of a thick centre 

 with shoots radiating out on all sides. They liquefy the gelatin 

 more slowly than the b. subtilis. This .method of isolation is 

 not always successful, partly because along with the tetanus 



