CHOLERA 175 



and the production of indol and nitrites has proceeded 

 sufi&ciently far to cause the appearance of the indol re- 

 actions (a distinct rose-madder tint) on the addition of 

 a drop of pure sulphuric acid. The indol reaction was 

 introduced in the year 1884 ; previous to this chief reliance 

 was placed on the appearance of the young colonies. 



Many other organisms besides Koch's ' comma ' also 

 produce indol and nitrates in sufficient quantities to yield 

 the indol reaction, but not in this time (twelve hours), so 

 that if the indol reaction is obtained, and the organisms are 

 microscopically similar to Koch's ' comma,' we may report 

 positively without delay. It is always advisable to adopt 

 this method of inoculation into Dunham solution, because 

 not only do we get the indol reaction, but a plentiful crop 

 of organisms, probably nearly a pure culture, on which to 

 do further work. In cases of true cholera the organism 

 frequently cannot be demonstrated in the stool when the 

 patient is on the way to recovery, so that the inability to 

 demonstrate the organism in cases three or four days from 

 commencement of the attack must not be taken as evidence 

 that the disease was not true cholera. A detailed account 

 of the cholera vibrio is contained in Dr. Klein's Appendix 

 to the Local Government Board Eeport, 1893, from which 

 most of the above details are taken. 



There is no doubt that 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 pro- 

 ducing cholera, but not all exactly similar in their cultural 

 aspects. 



Sheridan Delepine and James Eichmond, in a paper on 

 the ' Bacteriological Diagnosis of Cholera ' (the Journal of 

 Pathology and Bacteriology, April, 1895), call attention to 

 the danger of placing over-much confidence in the bacterio- 

 logical examination alone, and neglecting the clinical 



