TYPHOID BACILLUS 149 



important lactic acid producer is Bact. bulgaricum of Massol. 

 This is the principal ferment of the eastern sour milks, Kumyss 

 and Yoghurt Because of the large amount of lactic acid formed 

 by this germ, Metchnikorf has advocated cultures of it and sour 

 milk made by it in the treatment of intestinal putrefaction and 

 fermentation. The Bacterium bulgaricum produces a soft milk 

 curd and an excess of lactic acid and alcohol. The bacteria are 

 non-motile, non-spore forming, Gram positive and vary from 2fj. 

 to 50^ in length. They grow with difficulty in the laboratory, best 

 on milk and whey. Optimum temperature 44 C. They form 

 branching filamentous colonies. Milk is coagulated in 18 hours 

 at 44 C. and in 36 hours at 37 C. The clot is not dissolved. 

 Gelatine is not liquefied. 



TYPHOID BACILLUS. 



Bacterium Typhi. Koch and Eberth. 



Bacillus Typhosus. 



Typhoid Bacillus. (Fig. 49.) 



A most important pathogenic organism that 

 causes typhoid fever. 



Morphology and Stains. Generally short 

 plump rods i to 3/x long, and .6 to .8/1 broad. 

 Forms long threads in cultures, especially on 

 potatoes. Polar metachromatic bodies are 

 sometimes seen as are unstained areas when 

 alkaline methylene blue is used. The rod is FIG. 49. Typhoid 

 flagellated (peritrichous) ; contains no spores ; g ^ a (Kokand Was- 



exhibits pleomorphic and involution forms; is sermann.) 

 actively motile, and stains with all the basic 

 aniline dyes, but not by Gram's method. 



Vital Resistance. The thermal death-point is 60 C., ten to 

 fifteen minutes. Remains alive in ice for months; even the tempera- 

 ture of liquid air does not destroy it. In distilled water it lives for 

 months, but if other saprophytic bacteria are associated with it, 



