Ethel M. Dotdge 



419 



Capsules. The viscid nature of the growth on agar and other media 

 points to the presence of a capsule. This is most clearly seen in potato 

 cultures. Examined after 24 hours at 30° C. each rod is surrounded by 

 a white halo; when stained with carbol fuchsin the rod stains intensely 

 and the capsule is pale with a feebly stained margin (Fig. 5). As the 

 culture grows older the capsule becomes more evident, and when stained 

 with carbol fuchsin the rod and capsule stained as described above are 

 embedded in a slimy mass which stains pink. 



r#" & 



Fig. 5. Rods from potato culture, 24 hours at 30° C. Stained with carbol fuchsin. 



Involution forms have been found in old gelatine cultures. They 

 vary much in form; some are stout rods about 1/x thick in the centre 

 and tapering to pointed ends: others are longer threads up to 35 fj, long 

 and varying in thickness, curved and distorted and with or without 

 constrictions at irregular intervals. 



Staining reactions. The organism as taken from young cultures 

 stains evenly and intensely with carbol fuchsin and all the ordinary 

 aniline stains. In rods from older cultures all staining is fainter and 

 more irregular. It is not acid fast and stains only faintly with Loffler's 

 blue; it is Gram positive: no granules were observed in rods stained by 

 Neisser's method. . 



