THE COMMA BACILLUS OF ASIATIC CHOLERA 153 



Microscopical Appearances. The bacilli lie in clusters either in 

 or between the epithelial cells, the size and form of the rods being very 

 similar to the Bacillus tuberculosis. 



Staining Reactions. They stain with difficulty, are acid-resisting 

 when stained by the methods for tubercle bacilli (see Technique, 13 

 and 14), but are decolorized when treated one minute with absolute 

 alcohol. The reaction with the Gram method is positive. 



Biological Characters. Doutrelepont and Mattel-stock obtained a 

 culture of a similar organism on coagulated hydrocele fluid, which 

 coloured the medium brown ; further cultivation was not successful. 



Differential Diagnosis (see Bacillus Tuberculosis, p. 137). It is 

 most likely to be mistaken for the Bacillus tuberculosis in the examina- 

 tion of urine. 



THE COMMA BACILLUS OF ASIATIC CHOLERA. 



(Vibrio Cholerae Asiatic*.) 



In 1883 Koch discovered that in all cases of Asiatic cholera a 

 particular form of bacterium was present, and that these bacteria were 

 found exclusively in cases of genuine Asiatic cholera. 



Microscopical Appearances. Slightly curved rods with rounded 

 ends from 0'8 to 2 //, in length, and about 0*3 to 0'4 /x, in breadth. 

 The rods are usually curved like a comma, but are occasionally in the 

 form of a half circle, or two contact rods curved in opposite directions 

 may form an S-shaped figure. The typical comma shape is best observed 

 in specimens prepared from young cultures (see Photomicrograph, Fig. 56). 

 When newly-developed individual bacilli remain attached together, they 

 form long spirals. This condition is frequently observed in cultures, espe- 

 cially in old cultures or on the addition of weak antiseptics, i.e. alcohol. 

 In human cholera dejections, the spirillum forms are extremely seldom 

 observed. In the peritoneal exudate of inoculated guinea-pigs spirillum 

 forms are especially frequent. The spirilla are considered to be involution 

 forms. 



Motility. Strongly motile. When examined in a hanging-drop cul- 

 ture they resemble a swarm of gnats. The motility is due to one 

 flagellum separated at the end of the rod (Monotricha). (See Photomicro- 

 graph, Plate II., Fig. 10, stained by the author's orcein method). 



Spore Formation. Spores do not exist. The arthrospores described 

 by Hueppe have not been confirmed by other investigators. 



Staining Reactions. The best results are obtained with a satu- 

 rated watery solution of fuchsin or with carbol fuchsin. The stain must 



