MICROSCOPICAL CHARACTERS 



461 



o-: 



longer spiral filaments, showing a large number of turns. In 



film preparations made 



from the intestinal con- ^^^flflBB^^^ 



tents in typical cases, 



these organisms are pre- 

 sent in enormous num- 

 bers in almost pure 



culture, most of the 



spirilla lying with their 



long axes in the same 



direction, so as to give 



the appearance which 



Koch compared to a 



number 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 nagellum is present 



at one end only (Fig. 

 136). It is very deli- 

 cate, and measures four 

 or five times the length 

 of the organism. 

 Cholera spirilla do not 

 form spores. In old cul- 

 tures the organisms may 



*S present great variety in 



size and shape. Some 

 are irregularly twisted 

 filaments, sometimes 

 globose, sometimes 

 clubbed at their extremi- 

 ties, and also showing 



> 



FIG. 136. Cholera spirilla stained to show 

 the terminal flagella. See also Plate IV., 

 Fig. 19. x 1000. 





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. 



FIG. 137. 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. 



