238 BACILLUS DIPHTHERIJE. 



other; of a dumb-bell shape or bulging in the middle. 

 Branching forms are also met with occasionally. It usually 

 occurs singly and rarely forms chains. It exhibits a slight 

 tendency to parallelism. It has been suggested that there 

 might be some relationship between the tubercle bacillus, the 

 actinomyces, and the diphtheria bacillus, because all three 

 exhibit the same variability as to form (Fig. 98). 



Bacillus diphtherias has no flagella and is not motile. Spore- 

 formation has not been observed. It is easily stained with the 

 anilin dyes, but best with Loeffler's alkaline methylene-blue. 

 Gram's method is also applicable. It does not, however, 



FIG. 98. 



Extremely long form of diphtheria bacillus. This culture has grown on artificial 

 media for four years and produces strong toxin. X 1100. (Park.) 



stain uniformly, but presents spaces suggestive of sporulation 

 or fragmentation of the germ. This is especially marked in 

 the larger organisms. Polar bodies are common in the 

 smaller, more regular varieties. They are the Babes-Ernst 

 bodies. They have a diameter greater than that of the bacil- 

 lus and give rise to the dumb-bell shape. These irregularities 

 in staining are more apparent in germs which are cultivated 

 artificially than in those obtained directly from the lesions. 

 As the culture ages the staining becomes less characteristic. 

 Neisser's stain brings out the polar bodies very strongly. 

 The film is stained for two or three minutes in the following 

 solution : 



