736 Tuberculosis 



duce any lesion in rabbits or guinea-pigs ; that no morphologic 

 relationship could be observed between the bacilli and their 

 virulence; that highly virulent bacilli grew scantily on 

 culture-media and were short lived; that bacilli of widely 

 different virulence may be present in any one of the various 

 human tuberculous lesions ; that in scrofulous lymphadenitis 

 the bacilli are usually of low virulence; the bacilli in pul- 

 monary tuberculosis with ulcer ation are of feeble virulence, 

 those of miliary tuberculosis of very great virulence; that 

 the so-called " healed tubercles " of the lung may contain 

 virulent or attenuated bacilli; that individuals suffering 

 from infection with a bacillus of a low grade of virulence 

 may be again infected with extremely virulent tubercle 

 bacilli; that chronic tuberculosis of the bones may contain 

 bacilli of high or low virulence, and that variations in 

 virulence among human tubercle bacilli may possibly some- 

 times depend, like many other qualities among tubercle 

 bacilli, on peculiarities inherited through serial trans- 

 missions in other than human hosts. 



Chemistry of the Tubercle Bacillus. Klebs* found 

 that the tubercle bacillus contains two fatty bodies, one 

 of which, having a reddish color and melting at 42 C., 

 can be extracted with ether. It forms about 20 per cent, 

 by weight of the bacillary substance. The other is in- 

 soluble in ether, but soluble in benzole, with which it can 

 be extracted. It melts at about 50 C. and constitutes 

 1.14 per cent, of the bacillary substance. After removing 

 these fatty bodies the bacilli fail to resist the decolorant 

 action of acids when stained by ordinary methods, so that 

 it seems probable that their acid-resisting power depends 

 upon them. 



De Schweinitzf showed that it was possible to extract 

 from the tubercle bacillus an acid closely resembling, if 

 not identical with, teraconic acid. It melts at 161 to 164 C. 

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

 necrotic changes caused by the organism depend upon it. 



RuppelJ 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 



* "Centralbl. f. Bakt.," 1896, xx, p. 488. 



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

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



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



