98 ESSENTIALS OF BACTERIOLOGY. 



and cultivated by Koch, who made his investigations public on 

 the 24th of March, before the Physiological Society of Berlin, 

 in the year 1882. 



Origin. In various tubercular products of man and other 

 animals. 



Form. Very slender rods, nearly straight, about one-quarter 



FIG. 51. 



\ 



o 



I / 



-s 



Tubercle bacilli in sputum, carbol-fuchsin, and methylin blue. Zeiss 1:12 oil 

 immersion. 



the size of a red corpuscle's diameter, their ends rounded, usu- 

 ally solitary, often, however, lying in pairs in such a manner as 

 to form an acute angle. Sometimes they are S -shaped. In 

 colored preparations little oval spaces are seen in the rod, which 

 resemble spores ; but the question of the existence of spores is 

 still undecided. 



Properties. Does not possess self-movement. 



Growth. Requires special media for its growth, and a temper- 

 ature varying but slightly from 37.5 C. It grows slowly, de- 

 velopufig first after ten days, reaching its maximum in three 

 weeks. It is facultative anaerobic. On gelatine it does not 

 form a growth. 



