CHAPTER XXT. 



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 

 ftom the bamllus typhi abdominalis. 



The organism, discovered by Eberth and by Gaffky, 

 generally recognized as the etiological factor in the 

 production of typhoid fever, may be described as 

 follows : 



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- 

 ably constant. Its morphology presents little that will 



FlQ. 56. 



Fig. 57. 





BaciUus typhi abdominalis from 

 culture twenty-four hours old, on 

 agar-agar. 



BaciUus typhi ahdominaMs show- 

 ing flagella stained by LSffler's 

 method. 



aid in its identification (see Fig. 56). It stains a trifle 

 less readily with the aniline dyes than do most of the 

 other organisms. It is very actively motile, and when 



