37 2 Tuberculosis 



The occurrence of tuberculosis in the inoculated animals 

 was decided by both macroscopic and microscopic tests. 



Lartigau found that human tubercle bacilli from different 

 sources produced varying degrees of tuberculosis in animals ; 

 that the injection of the same culture in different amounts 

 produces differing results ; that the extent and rapidity of 

 development usually corresponds to the virulence of the 

 culture ; that doses of i mg. of a very virulent culture may 

 induce general tuberculosis in rabbits in a very short time ; 

 that 20 mg. of a bacillus of low virulence may fail to pro- 

 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 ulceration 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. 



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



