3<5 



Tuberculosis 



a great impetus to investigations upon tuberculosis by the 

 discovery that the addition of from four to eight per cent, 

 of glycerin to bouillon and agar-agar made them suitable 

 for the development of the bacillus, and that a much more 

 luxuriant development could be obtained upon such media 

 than upon blood-serum. The growth upon "glycerin agar- 

 agar" (Fig. 107) resembles that upon blood-serum. A criti- 

 cal study of the relationship of massive development and 



glycerin was made by Kimla, 

 Poupe, and Vesely,* who found 

 that the most luxuriant growth 

 occurred when the culture media 

 contained from 5 to 7 per cent, 

 of glycerin. As tubercle bacilli 

 require considerable oxygen for 

 their proper development, they 

 grow only upon the surface of 

 the bouillon, where a thick wrin- 

 kled growth forms. This growth 

 is rather brittle, and after a 

 time subsides. 



Dogs' Blood-serum. A very 

 successful method of isolating 

 the tubercle bacillus has been 

 published by Smith. f A dog is 

 bled from the femoral artery, the 

 blood being caught in a sterile 

 flask, where it is allowed to co- 

 agulate. The serum is removed 

 with a sterile pipet, placed in 

 sterile tubes, and coagulated at 

 75-76 C. Smith prefers to use 

 a test-tube with a ground cap, having a small tubular aper- 

 ture at the end, instead of the ordinary test-tube with the 

 cotton plug. The object is to prevent the contents of the 

 tube from drying during the necessarily long period of in- 

 cubation. 



To the same end the ventilators of the incubator are 

 closed, and a large evaporating dish filled with water is 



* "Revue de la Tuberculose," 1898, vi, p. 25. 



t "Transactions of the Association of American Physicians," 1898, 

 vol. xm, p. 417. 



Fig. 107. Bacillus tuber- 

 culosis on " glycerin agar- 

 agar." 



