398 



BACTERIOLOGY. 



FIG. 86 



of a slightly alkaline reaction. Gelatin is slowly lique- 

 fied, with the coincident production of a small amount 

 of gas. Neither agar-agar nor 

 blood-serum are liquefied by its 

 growth. 



The addition to the media of 

 from 1.5 to 2 per cent, of glucose, 

 0.1 per cent, of indigo-sodium- 

 sulphate, or 5 per cent, by volume 

 of blue litmus tincture favors its 

 growth. 



It grows well in alkaline bouil- 

 lon under an atmosphere of hy- 

 drogen. 



It may be cultivated through 

 numerous generations under arti- 

 ficial conditions without loss of 

 virulence. 



Appearance of the colonies. The 

 colonies on gelatin under an at- 

 mosphere of hydrogen have, in 

 their early stages, somewhat the 

 appearance of the colonies of the 

 common bacillus subtilis, viz., they 

 have a dense, felt-like centre sur- 

 rounded by a fringe of delicate 

 radii. The liquefaction is so slow 

 that the appearance is retained for 

 a relatively long time, but eventu- 

 ally becomes altered. In very old 

 colonies the entire mass is made 

 up of a number of distinct threads 



Colonies of the tetanus 

 bacillus four days old, made 

 by distributing the organ- 

 isms through a tube nearly 

 filled with glucose-gelatin. 

 Cultivation under an at- 

 mosphere of hydrogen. 

 (From FRANKEL and 

 PFEIFPEK.) 



