590 



Typhoid Fever 



Morphology. The typhoid bacillus measures about i to 3 /* (2 to 

 4 n Chantemesse, Widal) in length and 0.5 to 0.8 ^ in breadth 

 (Sternberg). The ends are rounded, and it is exceptional for the 

 bacilli to be united in chains. The size and morphology vary with 

 the nature of the culture-medium and the age of the culture. Thoi- 

 not and Masselin,* in describing these morphologic variations, point 

 out that when grown in bouillon the typhoid bacillus is very slender; 

 in milk it is stouter; upon agar-agar and potato it is thick and short; 

 and in old gelatin cultures it forms long filaments. It produces 

 no spores. 



Flagella. The organisms are actively motile and are provided 

 with numerous flagella, which arise from all parts of the bacillus 

 (peritricha), and are 10 to 20 in number. They stain well by 



Fig. 248. Bacillus typhosus. 



Loffier's method. The movements of the short bacilli are oscillating; 

 those of the longer bacilli, serpentine and undulating. 



Staining. The organism stains quite well by the ordinary methods, 

 but not by Gram's method. As it gives up its color in the presence 

 of almost any solvent, it is difficult to stain in tissue. 



When sections of tissue are to be stained for the demonstration of 

 the typhoid bacilli, the best method is to allow them 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 fifteen minutes in a 

 solution of distilled water, 100, fuchsin i, and phenol 5. After 

 staining they are washed in distilled water containing i per cent. of 

 acetic acid, dehydrated in alcohol, cleared, and mounted. In such 

 * "Precis de Microbie," Paris, 1893. 



