206 APPLIED BACTERIOLOGY 



the microscopic appearance is doubtful or negative. In 

 true cholera the ileum presents a characteristic appearance, 

 the mucous and serous coats being congested. 



Within recent years spirilla have been cultivated from 

 cases of true cholera from different localities, and although 

 they very closely resembled Koch's comma organisms, yet 

 they differed slightly in cultural characters. Therefore the 

 term Koch's ' comma ' should be taken to include a group 

 of organisms in varying stages, or more probably a group 

 of organisms all capable of producing cholera, but not all 

 exactly similar in their cultural aspects. 



Bacteriological Diagnosis. — To establish the identity of an 

 organism with Koch's ' comma,' it should be found to 

 resemble it (1) morphologically ; (2) culturally ; (3) in its 

 chemical products ; (4) in its pathogenic effects on animals. 



' Comma ' bacilli straight from the stool are short, thick, 

 curved rods, about 3"0 mm. long and 0'3 mm. thick. 

 They also possess three or four flagella, but after subculture 

 they are usually found to possess only one terminal flagella. 

 It is also a remarkable fact that the flagella of organisms 

 fresh from the stool stain readily with the ordinary aniline 

 dyes, while the flagella in the organisms taken from a 

 culture require mordanting before they will take the stain. 

 On repeated subculture, the organism grows out into longer 

 and thinner rods, bearing very little resemblance to bacilli 

 straight from the stool; hence it materially follows that 

 cultures met with in bacteriological laboratories are not 

 always typical. 



In examining the body of a patient who had died from 

 supposed Asiatic cholera, the condition of the ileum should 

 first be noted, and a portion preserved for examination by 

 being ligatured at both ends, and then placed in a tightly- 

 corked bottle, if the examination cannot be made at once. 

 In acute cases the mucous and serous coats are found 



