TYPHOID FEVER. 



367 



The organisms are actively motile, the motility prob- 

 ably being caused by the numerous flagella with which 

 the bacilli are provided. The flagella stain well by 

 Loffler's method, and, as they are numerous (ten to 

 twenty) and readily demonstrable, the typhoid bacillus is 

 the favorite subject for their study. The movements of 



FIG. 106. Bacillus typhi, from an agar-agar culture six hours old, showing the 

 flagella stained by Loffler's method; x 1000 (Frankel and Pfeiffer). 



the short bacilli are oscillating, those of the longer indi- 

 viduals serpentine. 



The organism stains quite well by the ordinary meth- 

 ods, but loses the color entirely when stained by Gram's 

 method. Its peculiarity of staining is the readiness with 

 which the bacillus gives up its color in the presence of 

 solvents, so that it is particularly difficult to stain it in 

 tissue. 



When sections are to be stained the best method is to 

 allow the tissue to remain in Loffler's alkaline methylene 

 blue for from fifteen minutes to twenty-four hours, then 

 wash in water, dehydrate rapidly in alcohol, clear up in 

 xylol, and mount in Canada balsam. Ziehl's method 

 also gives good results. The sections are stained for fif- 

 teen minutes in a solution of distilled water 100, fuch- 



