45 2 Diphtheria 



granules can be denned at the ends of the bacilli. Occa- 

 sional branched forms are observed, and the diphtheria 

 bacillus probably belongs to the higher bacteria, though 

 Abbott and Gildersleeve* do not regard branching as a phase 

 of the normal development of the organism, do not find it. 

 common upon the standard culture media, and so do not 

 think that it is properly classified elsewhere than among the 

 bacilli. 



No flagella have been demonstrated upon the bacillus, 

 and it is non-motile. It is almost purely aerobic. 



The involution of the diphtheria bacillus seems to occur 

 in proportion to the rapidity of its growth. Upon Loffler's 

 serum mixture, which seems best adapted for its cultivation, 

 the involution of the organism takes place with great 

 rapidity, so that large clubbed organisms and large or- 

 ganisms with polar granules are very common. On the 

 other hand, upon agar and glycerin agar-agar, where the 

 organism grows very slowly, it usually appears in the form 

 of short spindle and lancet shapes. So different are these 

 forms that a beginner would certainly fail to recognize them 

 as identical. The small short forms also stain much more 

 uniformly than the large club-shaped bacilli. 



Wesbrook f has established certain morphologic types of 

 the bacillus (see illustration), and from the appearances 

 presented draws conclusions regarding their virulence, 

 which are confirmed by Gorham,J but disputed by Denny. 

 The rapidly growing bacilli with clubbed ends and polar 

 granules are supposed to be virulent forms; the slowly 

 growing, uniformly staining forms, non-virulent bacilli. 

 Park and Denny believe that the uniformly staining bacil- 

 lus, when it develops in blood-serum cultures, is the pseudo- 

 diphtheria bacillus, an entirely different organism. 



Staining. The bacillus can readily be stained with aque- 

 ous solutions of the analin colors, but more beautifully 

 and characteristically with Loffler's alkaline methylene- 

 blue: 



* "Centralbl. f. Bakt.," etc., Dec. 18, 1903, Bd. xxxv, No. 3. 



t "Trans. Assoc. Amer. Phys.," 1900, and "Trans, of the Amer. 

 Public Health Assoc.," 1900. 



t "Journal of Medical Research," N. S., vol. i, p. 201, 1901. 



American Public Health Association (New Orleans) Meeting, 

 1902. 



