176 APPLIED BACTERIOLOGY 



characters, when determining whether a particular death is 

 due to true cholera. They also draw attention to the 

 fact that the organism in different years and in different 

 places exhibits somewhat varying characters, and point out 

 that these differences may have led observers to ignore the 

 presence of true cholera, because such spirilla as they 

 found did not possess precisely the characters that are 

 supposed to distinguish the true cholera spirillum. They 

 also draw attention to records where several varieties of 

 ' commas ' were found in cases of cholera, and that these 

 variations were observed, not merely after repeated sub- 

 culture, but when the organisms were taken direct from the 

 ileum or stool. 



For example, there are organisms which have produced 

 disease clinically identical with cholera which have ex- 

 hibited unusual variations from the time generally required 

 to give the indol reaction or to liquefy gelatine, and these 

 observers found that on growing a variety of the cholera 

 organism repeatedly in broth which had been made alka- 

 line, the indol reaction became less and less marked, and 

 the organism liquefied gelatine more slowly ; but on trans- 

 ferring them to ordinary peptone salt solution, the indol 

 reaction was again obtained in a few hours. 



As an instance of an outbreak possessing many of the 

 characters of cholera, we may recall the Greenwich 

 epidemic diarrhoea outbreak, which began on October 4, 

 1894, and lasted some twenty days, during which there 

 were as many as 245 cases ; the mortality, however, was 

 comparatively low, as there were only eleven deaths. On 

 bacteriological examination, Koch's ' comma ' could not be 

 found, but an organism of the Proteus vulgaris type was 

 isolated. 



Occurrence and Distribution. — The disease is endemic in 

 the Delta of the Ganges and in Asia ; in countries in which 



