Staining 571 



spiral threads unmistakable spirilla develop. Frankel found 

 that the exposure of the cultures to unusually high temperatures, 

 the addition of small amounts of alcohol to the culture-media, and 

 other unfavorable conditions lead to the production of spirals 

 instead of "commas." 



The cholera spirilla are actively motile, and in hanging-drop 

 preparations can be seen to swim about with great rapidity. Both 

 comma-shaped and spiral organisms move with a rapid rotary 

 motion. 



The presence of a single flagellum attached to one end can be 

 demonstrated without difficulty. 



.- 



Fig. 237. Cover-glass preparation of a mucous floccule in Asiatic cholera. 



X 650 (Vierordt). 



Involution-forms of bizarre appearance are common in old 

 and sometimes in fresh cultures. Many individuals show by 

 granular cytoplasm and irregular outline that they are degenerated. 

 Cholera spirilla from various sources differ in the extent of involution. 



In partially degenerated cultures containing long spirals, Hiippe 

 observed, by examination in the " hanging-drop," certain large 

 spheric bodies which he described as spores (arthrospores). Koch 

 and, indeed, all other observers fail to find spores in the cholera 

 organism, and the nature of the bodies described by Hiippe must 

 be regarded as doubtful. 



Staining. The cholera spirillum stains well with the ordinary 

 aqueous solutions of the anilin dyes, especially fuchsin. At times 

 the staining must be continued for from five to ten minutes to se- 

 cure homogeneity. The organism does not stain by Gram's method. 

 It may be colored and examined while alive; thus, Cornil and 



