TUBEBOVLOSIS. 81 



addition of barium hydrate precipitates barium sulphate, which 

 may be removed by filtration and the filtrate precipitated with 

 alcohol. The substance thus obtained does not respond to any of 

 the color reactions for proteids with the exception of the biuret test. 

 Ruppel believes it to be a protamin, and proposes for it the name, 

 tuberculosamin. He believes that in the tubercle bacillus this 

 protamin is combined with nucleinic acid, and, indeed, from the 

 part insoluble in 1 per cent, sulphuric acid he obtained a nucleinic 

 acid which contains 9.42 per cent, of phosphorus. He proposes 

 that the nucleinic acid in the tubercle baciUus be known as tubercu- 

 linic acid. 



According to Behring,* tuberculinic acid, as prepared by Ruppel, 

 contains a histon-like body, on the removal of which the tubercu- 

 linic a«id is obtained chemically pure. Behring states that the 

 nucleinic acid obtained from tubercle baciUi, or tuberculinic acid, 

 is quite diflferent from all other nucleinic acids. To this substance 

 he attributes the toxic action of tubercle bacilli, and he states that 

 one gram of tuberculinic acid is capable of destroying the life of 

 600 grams of normal guinea-pig when injected subcutaneously, and 

 90,000 grams when introduced intra-cerebrally, and that the 

 same amount of tuberculinic acid is capable of destroying the life of 

 60,000 grams of guinea-pig, already infected with tuberculosis, when 

 administered subcutaneously ; and 40,000,000 grams of the same 

 tissue when injected intra-cerebrally. In distinguishing physiolog- 

 ically between tuberculinic and other nucleinic acids, tuberculous 

 animals should be selected on account of their greater susceptibility 

 to the tuberculinic acid. 



Levene,^ agrees with Ruppel that the tubercle bacillus contains 

 both free and combined nucleinic acid, and the following is his 

 statement concerning the method of obtaining both of these : " With 

 the view of obtaining the free nucleic acid, neutralized, dried and 

 pulverized baciUi were repeatedly extracted with a 5 per cent, 

 sodium chlorid solution, and an 8 per cent, ammonium chlorid solu- 

 tion. The extracts obtained were then treated with picric acid and 

 acidulated with acetic acid. To the filtrate from this precipitation 

 alcohol was added, and the precipitate thus formed redissolved in 

 water and reprecipitated with alcohol. The perfectly white pre- 

 cipitate was redissolved in water, slightly acidulated with acetic 

 acid, and treated with a solution of cupric chlorid. The precipi- 

 tate thus formed was washed with water until copper-free ; then 

 with alcohol until chlorin-free ; finally with ether and then dried in 

 vacuo over sulphuric acid, and in air-bath at 105° to constant 

 weight. . . . The residue after the sodium chlorid treatment was 

 treated for two hours with a 4 per cent, solution of sodium hydrate 



' Berliner Uinische Wochenachrift, 36. 

 ^ Journal of Medical B^earch, 1, 1901. 



