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 variations in their characters, and, further, that 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 re- 

 garded 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 below. 



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 



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