3 so MANUAL OF BACTERIOLOGY. 



to have been made successfully to prove the pathological sig- 

 nificance of the organism. 



The bacillus is described as non-motile, varying from 6-8 ii 

 to I0-20 II in length. It appears mostly or exclusively to be 

 mixed with other bacteria. Bernheim observed the organism 

 in ulcerative stomatitis mixed with spirochetae. 



Bacillus Tuberculosis. — A slim bacillus with rounded ends 

 1.5 to 4 /* in length. It very frequently presents a beaded ap- 

 pearance, owing to its being dotted with bright, shining spots. 



■^'/■f-''' 



^ v'-" 



" >:_•; ^-^ 



V •"-. 



\ 



I 





Fig. 90.— Bacillus tuberculosis, from a pure culture. (X looo.) 



Branching forms have been described. The tubercle bacillus 

 is considered by some to be a member of the actinomyces group. 

 It is not motile. It has not been proved that spores are formed ; 

 nevertheless certain structures, like caseous lymph-nodes, have 

 been shown to be capable of infecting guinea-pigs with tuber- 

 culosis, although tubercle bacilli could not be demonstrated 

 m them with the microscope. This makes it seem possible 

 that the organisms were present as spores which eluded the 

 microscopical examination. The tubercle bacilli stain with the 



