398 CHOLERA. 



We have mentioned these examples in order to show 

 some of the difficulties which exist in connection with this 

 subject. There is still considerable doubt as to what tests 

 are sufficient to distinguish Koch's spirillum from others 

 closely resembling it, and even as to whether Pfeiffer's 

 reaction can be accepted as an absolute means of diagnosis. 

 It is important to note that, on the one hand, spirilla which 

 have been judged to be of different species from the cholera 

 organism, have been cultivated from cases in which cholera- 

 like symptoms were present, and on the other hand, in 

 cases of apparently true cholera considerable variations 

 in the characters of the cholera organisms have been 

 found. Such variations have especially been recorded by 

 Surgeon-Major Cunningham in India. It is therefore quite 

 an open question whether some of the organisms in the 

 former case may not be cholera spirilla which have under- 

 gone variations as a result of the conditions of their growth. 

 That such variations may occur we have a considerable 

 amount of evidence. The subject is made still more diffi- 

 cult by the results of Sanarelli, who states that he has 

 cultivated from contaminated river water a number of 

 vibrios which conform in all their characters to those 

 of Koch's spirillum and which have also the same patho- 

 genic effects on animals, and also others which differ only 

 in minor points, so that they may be regarded merely as 

 varieties. 



In spite of what has been stated above, the great bulk 

 of evidence goes to show that Asiatic cholera always spreads 

 as an epidemic from places in India where the disease is 

 endemic, and that its direct cause is Koch's spirillum. It 

 is sufficient to bear in mind that the choleraic symp- 

 toms may be produced by other causes, and that in 

 some of these cases spirilla which have some resem- 

 blance to Koch's organism may be present in the intes- 

 tinal discharges, though rarely in large numbers. In 

 such cases the disease is usually of a comparatively 

 mild nature and remains local, never spreading widely as 

 an epidemic. 



