NON-SPORING BACILLI 231 



especially in the animal tissues) ; grows well on usual media ; 

 curdles milk with acid production in forty-eight hours ; 

 forms acid and gas with dextrose and lactose (gas = 

 hydrogen and carbonic acid gas in proportion of 2 to i); 

 some ferment saccharose ; some are weak and aberrant ; 

 not usually pathogenic (agonal or post-mortem invasion 

 excluded) ; sometimes causes peritonitis, cholecystitis, 

 pyelitis, and cystitis ; can precipitate cholesterin from 

 solution (hence may cause gall-stones) ; cannot peptonize 

 native proteids (casein and egg albumen, etc.). 



Cultures. In broth : uniform turbidity. In gelatin stab : 

 growth along whole line of stab and film-like abundant 

 growth on surface, but no liquefaction. On gelatin plate : 

 surface colonies are apt to show the typical grape-leaf 

 formation. (In gelatin stab, a few gas bubbles may form, 

 see later.) On agar slope : a dense glistening white or 

 greyish growth. Same on blood serum. On agar plate : 

 surface colonies show grape-leaf structure. On potato : 

 abundant growth, at first greyish- white, turning later to 

 yellowish-brown. Cultures are characterized by a peculiar 

 foetid odour, not unlike that of diluted faeces. Grows well 

 on media containing urine and bile. In peptone water : 

 forms indol. In milk : acidity and clot. In lactose litmus 

 agar : the medium becomes red along stab, and gas bubbles 

 appear. In carbohydrate media : acid and gas are formed 

 in presence of glucose, lactose, laevulose, galactose, 

 maltose, raffinose, mannite, dulcite, and sorbite ; and 

 occasionally in saccharose (cane sugar) and in the gluco- 

 sides, salicin and arbutin. Some varieties change neutral- 

 red, first to a rosy-red and then to a green fluorescence 

 (in glucose broth) ; and most reduce nitrates to nitrites. 

 Aerobe, but facultative anaerobe. Motile, having from 

 4-12 peritrichal flagella. 



B. Typhosus was discovered by Eberth in 1880 in the 

 spleen and mesenteric glands of persons dying of typhoid 

 or enteric fever. In such sections the bacilli occur in 

 groups, scattered individuals being rare. Gaffky in 1884 

 first grew it in pure culture and studied its characters. 



Characteristics. Short plump rod with rounded ends, 

 i to 3 micra long and 0*5 to o - 8 broad ; actively motile ; 

 numerous peritrichal flagella (10 to 14) ; growth less 



