CHAPTER XVIII. 



THE CHOLERA SPIRILLUM AND ALLIED 

 ORGANISMS. 



Introductory. It is no exaggeration of the facts to say that 

 previously to 1883 practically nothing of value was known 

 regarding the nature of the virus of cholera. In that year 

 Koch was sent to Egypt, where the disease had broken out, in 

 charge of a Commission for the purpose of investigating its 

 nature. In the course of his researches he discovered the 

 organism now generally known as the " comma bacillus " or 

 the "cholera spirillum." He also obtained pure cultures of 

 the organism from a large number of cases of cholera, and 

 described their characters. The results of his researches were 

 given at the first Cholera Conference at Berlin in 1884. 



Since Koch's discovery, and especially during the epidemic in 

 Europe in 1892-93, spirilla have been cultivated from cases of 

 cholera in a great many different localities, and though this 

 extensive investigation has revealed the invariable presence in 

 true cholera of organisms resembling more or less closely Koch's 

 spirillum, certain difficulties have arisen. For it has been 

 found that the cultures obtained from different places have 

 shown considerable variations in their characters, and, further, 

 spirilla which closely resemble Koch's cholera spirillum have 

 been cultivated from sources other than cases of true cholera. 

 There has therefore been much controversy, on the one hand, 

 as to the signification of these variations, whether they are 

 to be regarded as indicating distinct species or merely varieties 

 of the same species, and, on the other hand, as to the means 

 of distinguishing the cholera spirillum from other species which 

 resemble it. These questions will be discussed belo\v. 



In considering the bacteriology of cholera, it is to be borne in 

 mind that in this disease, in addition to the evidence of great 

 intestinal irritation, accompanied by profuse watery discharge, 

 and often by vomiting, there are also symptoms of general 



446 



