MALIGNANT EDEMA. 



461 



The bacillus of malignant edema stains well with ordi- 

 nary cold aqueous solutions of 

 the anilin dyes, but not by 

 Grain's method. 



The organism is not a difficult 

 one to secure in pure culture, 

 as has been said, generally con- 

 taminating tetanus cultures and 

 being much more easy to se- 

 cure by itself than its congener. 

 It is most easily obtained from 

 the edematous tissues of guinea- 

 pigs and rabbits inoculated with 

 garden-earth. 



The colonies which develop 

 upon the surface of gelatin kept 

 free of oxygen appear to the 

 naked eye as small shining 

 bodies with liquid grayish-white 

 contents. They gradually in- 

 crease in circumference, but do 

 not change their appearance. 

 Under the microscope they ap- 

 pear filled with a tangled mass 

 of long filaments which under a 

 high power exhibit individual 

 movement. The edges of the 

 colony have a fringed appearance, much like the hay or 

 potato bacillus. 



In gelatin tube-cultures the characteristic growth can- 

 not be observed in a puncture, because of the air which 

 remains in the path of the wire. The best preparation 

 is made by heating the gelatin to expel the air it may 

 contain, inoculating while still liquid, then replacing the 

 air by hydrogen, and sealing the tube. In such a tube 

 the bacilli develop near the bottom. The appearance of 

 the growth is highly typical, as globular circumscribed 

 areas of cloudy liquefaction result (Fig. 131), and may con- 



FlG. 131. Bacillus of malig- 

 nant edema growing in glucose 

 gelatin (Frankel and Pfeiffer). 



