TYPHOID FEVER. 



467 



arities mention that when grown in bouillon it is a very 

 slender bacillus ; in milk it is a large bacillus ; upon 

 agar-agar and potato it is very thick and short ; and in 

 old gelatin cultures it forms very long filaments. 



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. hi. — Bacillus typhi abdominahs, from an agar-agar culture six hours 

 old, showing the flagella stained by Loffler's method; x 1000 (Krankel 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. A peculiarity of the bacillus is the readiness 

 with which it 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- 



