THE CHOLERA SPIRILLUM. 



409 



cases, it will be found that these organisms are present in enor- 

 mous numbers in almost pure culture, and that most of the spi- 

 rilla lie with their long axes in 

 the same direction, so as to 

 give the appearance which 

 Koch compared to a school of 

 fish in a stream. 



They possess very active 

 motility, which is most marked 

 in the single forms. When 

 stained by the suitable methods 

 they are seen to be flagellated. 

 Usually a single terminal flagel- 

 lum is present at one end only 

 (Fig. 139). It is very delicate, 





Fig. 138. — Cholera spirilla, from a culture 



and measures four or five times ofagar of twenty-four hours' growth. 



Stained with weak carbol-fuchsin. X 1000. 



the length of the organism. In 



some varieties, however, there may be a flagellum at both ends, 

 or more than one may be present ; cultures obtained at differ- 

 ent places have shown considerable variations in this respect. 



^.^, 

 % 



v.. 







*/., 



*> - 









*% 



Fig. 139. — Cholera spirilla stained to 

 show the terminal flagella. X 1000. 



Fig. 140. — Cholera spirilla from an old 

 agar culture, showing irregularities in size 

 and shape, with numerous faintly stained 

 coccoid bodies — involution forms. 



Stained with fucllsin. X 1000. 



Cholera spirilla do not form spores. In old cultures, however, 

 small, rounded, and highly refractile bodies may be found in the 

 organisms, which have been regarded by Hueppe as " arthro- 

 spores," but which are in reality merely the result of degenera- 



