Toxic Products 373 



De Schweinitz * showed that it was possible to extract 

 from the tubercle bacillus an acid closely resembling, if 

 not identical with, teraconic acid. It melts at i6i-i64 

 C. and is soluble in ether, water, and alcohol. He thinks 

 the necrotic changes caused by the organism depend upon it. 



Ruppel f believes that three different fatty substances 

 are present in the tubercle bacillus, making up from 8 to 

 26 per cent, by weight. The first can be extracted with 

 cold alcohol, the second with hot alcohol, the third with 

 ether. In addition to the fatty substance Ruppel also 

 found what he believes to be a protamin and calls tuber- 

 culosamin. It seems to be combined with nucleinic acid, 

 and, indeed, from it he isolated an acid for which he proposes 

 the name tuberculinic acid. 



Behring % found that this acid contained a histon-like 

 body whose removal left chemically pure tuberculinic acid. 

 One gram of this acid is capable of killing a 6oo-gram 

 guinea-pig when administered beneath the skin. One 

 gram is fatal to 90,000 grams of guinea-pig when introduced 

 into the brain. If injected into tuberculous guinea-pigs it 

 is much more fatal, i gram destroying 60,000 when injected 

 subcutaneously and 40,000,000 when injected into the 

 brain. 



Levene also found free and combined nucleinic acid 

 varying in phosphorus content from 6.58 to 13.19 per cent. 

 He also found a glycogen-like substance that reduced 

 Fehling's solution when heated with a mineral acid. 



An important variation in the metabolism of the human 

 and bovine tubercle bacilli has been pointed out by Theobald 

 Smith, || who observed that cultures of the two organisms 

 upon glycerine bouillon differed in the induced reaction of 

 the media. The cultures of the bovine bacillus tend toward 

 neutrality, those of the human bacillus toward acidity. 

 This chemical difference is an adjunct to our means of 

 differentiating the two organisms. 



Toxic Products. In 1890 Koch** announced some ob- 

 servations upon the toxic products of the tubercle bacillus 



* "Trans. Assoc. of Amer. Phys.," 1897; "Centralbl. f. Bakt," etc., 

 Sept. 15. 1897, Bd. xxn, p. 200. 



t " Zeitschrift fur physiol. Chemie," 1899, xxvi. 

 t" Berliner klin. Wochenschrift," xxxvi. 

 "Jour. of Med. Research," I, 1901. 

 || "Trans. Assoc. Amer. Phys.," 1903, vol. xvm, p. 109. 

 **" Deutsche med. Wochenschrift," 1891, No. 343. 



