47 2 Diphtheria 



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, 



t \^e I,,-, 



JjWi \&* 



'*** / 'tf| 



Fig. 140. Wesbrook's types of Bacillus diphtheriae : a, c, d, Granular 

 types; a 1 , c 1 , d l , barred types; a 2 , c 2 , d 2 , solid types. X 1500. 



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. 



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



