TUBERCULOSIS. 



381 



all a favourable medium. Some increase took place, but there 

 was no continuous growth over the inoculated area. 



Glycerine Agar-agar. Nocard and Roux were among those who 

 worked at the subject and confirmed Koch's 

 observations, Nocard attempted to get 

 cultures of avian tuberculosis on blood serum 

 to which peptone, salt, and cane sugar had 

 been added. The results were more success- 

 ful than with ordinary serum. But he 

 encountered a difficulty in the rapid drying 

 of the surface of the medium, which rendered 

 the tubes unfit for use. It occurred to 

 Nocard and Roux to obviate this by the 

 addition of a hygroscopic agent, and accord- 

 ingly they added sterilised glycerine. The 

 result, which far exceeded their expectation, 

 evidently was not solely attributable to the 

 prevention of desiccation. Following up 

 their discovery, and 

 being anxious to find 

 a medium more easily 

 prepared than blood 

 serum, they added 



6 to 8 per cent, of glycerine to ordinary 

 nutrient agar-agar. The bacillus grew so 

 abundantly in this mixture that a culture 

 in fifteen days equalled in extent a culture 

 on blood serum which was several weeks old. 

 The bacillus was found to grow abundantly 

 in veal broth, to which glycerine had been 

 added in the proportion of 5 per cent., the 

 bottom of the flask being covered in about 

 three weeks with a flocculent deposit, having 

 some resemblance to anthrax cultivations 

 in liquid media. In beef broth, chicken 

 broth, and in Cohn's liquid, cultures were 

 obtained after the addition of glycerine. 



Description of Cultivations on Glycerine 

 Agar-agar. The cultivations on the sloping 

 surface of obliquely solidified glycerine agar- 

 agar begin to appear in from four to six days as very minute white 

 colonies. These steadily increase in size, and either look moist and 



FIG. 166. PURE-CULTI- 

 VATION IN GLYCERINE 

 AGAR-AGAR, after ten 

 months' growth. 



FIG. 167. -PURE-CULTI- 

 VATION IN GLYCERINE 

 AGAR-AGAR, A SUB- 

 CULTURE FROM A PURE- 

 CULTURE IN GLYCERINE- 

 MILK. In two months. 



