426 CHOLERA. 



and that its direct cause is Koch's spirillum. It is sufficient to 

 bear in mind that choleraic symptoms may be produced by other 

 causes, and that in some of such cases spirilla which have some 

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

 tinal discharges, though rarely in large numbers. 



Methods of Diagnosis. — In the first place, the stools ought 

 to be examined microscopically. Dried film preparations should 

 be made and stained by any ordinary stains, though carbol-fuch- 

 sin diluted four times with water is specially to be recommended. 

 Hanging-drop preparations, with or without the addition of a 

 weak, watery solution of gentian-violet or other stain, should also 

 be made, by which method the motility of the organism can be 

 readily seen. By microscopic examination the presence of spirilla 

 will be ascertained, and an idea as to their number obtained. 

 In some cases the cholera spirilla are so numerous in the stools 

 that a picture is presented which is obtained in no other condi- 

 tion, and a microscopic examination may be sufficient for prac- 

 tical purposes. According to Koch, a diagnosis was made in 

 50 per cent of the cases during the Hamburg epidemic by micro- 

 scopic examination alone. In the case of the first appearance 

 of a cholera-like disease, however, all the other tests should be 

 applied before a definite diagnosis of cholera is made. 



If the organisms are very numerous, gelatin or agar plates 

 may be made at once and pure cultures obtained. 



Schottelius' Enriching Method. — If the spirilla occur in com- 

 paratively small numbers, the best method is to inoculate pep- 

 tone solution ( I per cent) and incubate for eight to twelve hours. 

 At the end of that time the spirilla will be found on microscopic 

 examination in enormous numbers at the surface, and thereafter 

 plate cultures can readily be made. If the spirilla are very few 

 in number, or if a suspected water is to be examined for cholera 

 organisms, the peptone solution which has been inoculated should 

 be examined at short intervals till the spirilla are found micro- 

 scopically. A second flask of peptone solution should then be 

 inoculated, and possibly again a third from the second. By this 

 method, properly carried out, a culture may be obtained which, 

 though impure, contains a large proportion of the spirilla, and 

 then plate cultures may be made. 



When a spirillum has been obtained in pure condition by 

 these methods, the appearance of the colonies in plates should 



