318 



Tuberculosis 



a great impetus to investigations upon tuberculosis by 

 the discovery that the addition of 4-8 per cent, of gly- 

 cerin 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. 

 93) resembles that upon blood-serum. The growth upon 

 bouillon with added glycerin is also luxuriant. A critical 

 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 surface 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 



, 

 sterile tubes, and coagulated at 



75 -y6 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. xui, p. 417. 



