BACILLUS TUBERCULOSIS AND ALLIED ORGANISMS III 



tions little oval spaces are seen in the rod which resemble 

 spores, but have none of the properties of spores. (See Figs. 



47, 48.) 



Properties. Does not possess motility. 



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

 perature varying but slightly from 37.5 C. 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. The media should be slightly acid; 



Fig. 48. Giant-cell containing bacilli (from a photograph made by Dr. 

 Wm. M. Gray). 



growth mostly on surface. Subcultures grow more rapidly 

 than those direct from lesions. 



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

 culture, and obtained thereon very good growths. Stroke 

 cultures or test-tubes inoculated with small bits of tubercu- 

 lar tissue are placed in a well- ventilated and slightly humid 

 incubator at 37 C. for ten to fourteen days, when small 

 glistening white points appear, which then coalesce to form a 

 dry, white, scale-like growth. Under microscope, composed 

 of many fine lines containing the tubercle bacillus. 



Glycerin-agar. By adding 4 to 6 per cent, glycerin to 



