140 BACTERIOLOGY 



Indian Army, in London, who swallowed cultures of the 

 bacilli. 



Cholera bacilli appear as plump rods curved in the 

 direction of their long axis so as to resemble a comma in 

 figure, hence the name ' comma-bacillus ' (fig. 48) . They 

 have a twist in addition to this curve, so that they represent 

 a kind of spiral bacteria, and on this account have been 

 described as Vibrio or Spirillum cholera. The bacteria lie 

 connected in chains forming a tolerably steep spiral, and 

 when examined in the hanging drop show an exceedingly 

 lively motion, so that they might not inaptly be likened to 

 a swarm of midges dancing all over the field. Loftier found 

 a flagellum at one end of the cell. Koch was unable to 

 detect spores in them, but Fliigge, on the other hand, has 

 succeeded in demonstrating the formation of arthrospores. 

 They offer but small resistance to the influence of chemical 

 substances, and are destroyed by the acid of the gastric 

 juices ; and they refuse to grow upon feebly acid gela- 

 tine. They also perish at temperatures above 50 C., but 

 grow at room temperature as well as in the incubator. 

 Drying causes speedy loss of the power of development. 

 They stain in about ten minutes in diluted alcoholic solu- 

 tions of the aniline dyes, but the process is accelerated by 

 heating the solution, which also increases the intensity of 

 the stain. Special importance is to be attached to the fact 

 that they are decolorised if Gram's process be employed. 



Staining is done as follows : An alcoholic solution of 

 fuchsine or methyl violet is diluted with water sufficiently to 

 form a fairly strong aqueous staining fluid, which is poured 

 into a watch-glass. A trace of the pure culture or a minute 

 flake from the intestinal contents is next placed upon a cover- 

 glass and spread out by rubbing lightly with another laid over 

 it, after which the two glasses are drawn apart, dried in air, 

 grasped with a forceps and passed several times through a 



