448 



CHOLERA 



: 



film preparations made from the intestinal contents in typical 



cases, these organisms are 



< " * present in enormous 



!.<?X numbers in almost pure 



VL culture, most of the 



^ , spirilla lying with their 



-** C. long axes in the same 



direction, so as to give 

 the appearance which 

 Koch compared to a num- 

 ber 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 

 flagellum is present at 

 one end only (Fig. 132). 

 It is very delicate, and 

 length of the organism. 



FIG. 132. Cholera spirilla stained to show 

 the terminal flagella. See also Plate 

 IV., Fig 19. xlOOO. 



the 



measures four or five times 

 Cholera spirilla do not 

 form spores. In old cul- 

 tures the organisms may 

 present great variety in 

 size and shape. Some 

 are irregularly twisted 

 filaments, sometimes glo- , f 

 bose, sometimes clubbed , 4j 

 at their extremities, and * 

 also showing irregular 

 swellings along their 

 course ; others are short 

 and thick, and may 

 have the appearance of 

 large cocci, often stain- 

 ing faintly. All these 

 changes in appearance 

 are to be classed together 

 as involution forms. 



Staining. Cholera 

 spirilla stain readily with 

 the usual basic aniline stains, though Loffler's methylene-blue or 



FIG. 133. Cholera spirilla from an old agar 

 culture, showing irregularities in size and 

 shape, with numerous faintly - stained 

 coccoid bodies involution forms. 

 Stained with fuchsin. x 1000. 



