IIO ESSENTIALS OF BACTERIOLOGY 



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

 usually 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. (See Figs. 57, 58.) 

 Properties. Does not possess self-movement. 



X- 

 . 



I ' 



A - ^ 



Fig. 57. Tubercle bacilli in sputum; carbol-fuchsin and methylene-blue 

 (Zeiss one-twelfth oil-immersion). 



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

 ature varying but slightly from 37-5C. It grows slowly, 

 developing first after ten days, reaching its maximum in three 

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

 form a growth. 



Colonies on Blood-serum. Koch first used blood-serum for 

 culture, and obtained thereon very good growths. Test-tubes 

 with stroke culture are placed in the brood-oven at 37 C. 

 for ten to fourteen days, when small glistening white points 

 appear, which then coalesce to form a dry, white, scale-like 



