CHOLERA 209 



the peritoneum, although if the dose is a large one they 

 may be found in the blood and small intestine. 



The positive pathogenic effects of the cholera spirillum 

 on guinea-pigs are best demonstrated, according to Pfeiffer, 

 by taking a full needle-loop of the surface growth of an 

 agar culture, distributing this in 1 c.c. of sterile broth or 

 salt solution, and then injecting into the peritoneal cavity 

 of a guinea-pig. This should be a lethal dose for an animal 

 of average size — about 300 grammes — but for an animal 

 larger than this a somewhat larger dose should be employed. 



Sheridan Del6pine and James Kichmond, 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 

 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 spiriUum. 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- 



14 



