Morphology Staining 



633 



be found in water, air, soiled clothing, dust, sewage, milk, 

 etc., contaminated directly or indirectly with the intestinal 

 discharges of diseased persons. 



Morphology. The organism is a short, stout bacillus, 

 about i to 3 ft (2 to 4 ft Chantemesse, Widal) in length and 

 0.5 to 0.8 U broad (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. Thoinot and Masselin,* 

 in describing these morphologic variations, point out that 



Fig. 221. Bacillus typhi. 



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 fila- 

 ments. 



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 Loffler'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 loses the color when stained by Gram's method. 



* "Precis de Microbie," Paris, 1893. 



