TUBERCULOSIS. 



349 



rods certain granular masses which have been called spores 

 (Fig. 39, fr); but more careful study has disproved this con- 

 clusion. There are certain 

 facts, however, which have 

 led some bacteriologists to 

 insist that the organism must 

 produce spores. As we 

 have seen, active bacteria 

 are destroyed by a moder- 

 ately low temperature and 

 only spores resist high tem- 

 peratures. Now the tuber- 

 culosis bacillus will some- 

 times resist high tempera- 

 tures. It may even be 

 heated to a temperature of 

 boiling for an instant with- 

 out killing it, and such re- 

 sistance is only expected of spores. Moreover, the organisms 

 may be dried and yet remain alive for many months, and prob- 

 ably for years, without losing their vitality, a resistance which 

 again suggests the formation of spores. But the actual formation 

 of spores by this bacillus has not been seen and is still uncer- 

 tain. The important facts are that the organism can resist 

 drying for a long time and is able, under certain conditions, 

 to resist a heat close to boiling without being killed. These 

 facts are of great practical significance, for upon them must be 

 based all methods adopted looking toward disinfection. The 

 question whether they form spores is one of scientific interest 

 only. 



The formation of spores is not the only unsettled question 

 concerning the organism. It is even uncertain whether it 

 really belongs to the true bacteria. Within recent years it has 

 been found that, under certain conditions, the rods are seen to 



Tuberculosis bacillus, a, in a bit of animal tissue ; 

 b, showing irregularities resembling spores ; c, 

 typical appearance of the bacilli from ordinary cul- 

 tures. 



