350 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 /* 

 to 10-20 /* 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. 



FIG. 90. Bacillus tuberculosis, from a pure culture. (X 1000.) 



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 

 in 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 



