CHAPTER XXI. 



Typhoid fever Study of the organism concerned in its production The 

 bacterium coli commune Its resemblance to the bacillus of typhoid fever 

 Its morphological, cultural, and pathogenic properties Its differentiation 

 from the bacillus typhi abdominalis. 



THE organism, discovered by Eberth and by Gaff ky, 

 generally recognized as the etiological factor in the 

 production of typhoid fever, may be described as fol- 

 lows : 



It is a bacillus about three times as long as it is broad, 

 with rounded ends. It may appear at one time as very 

 short ovals, at another time as long threads, and both 

 forms may occur together. Its breadth remains toler- 



FlG. 60. 



FIG. 61. 



*T-vm? 



Bacillus typhi abdominalis from 

 culture twenty-four hours old, on 

 agar-agar. 



Bacillus typhi abdominalis show- 

 ing flagella stained by Loeffler's 

 method. 



ably constant. Its morphology presents little that will 

 aid in its identification (see Fig. 60). It stains a trifle 

 less readily with the aniline dyes than do most of the 

 other organisms. It is very actively motile, and when 



