534 A MANUAL OF BACTERIOLOGY 



agglutinins rarely develop so early as the second day of 

 the disease ; from that date they increase and about the 

 sixth day are marked. The titre remains high until the 

 seventeenth day and then drops, and by the twentieth 

 day or soon after the agglutinins disappear. The majority 

 of cases agglutinate up to a dilution of 1 in 60, some in 

 dilutions of 1 in 200, 400, 800, or 1,000. The majority 

 of fatal cases, even if they live for several days, do not 

 develop agglutinins. In no case did the serum agglutinate 

 a cholera-like vibrio isolated from the stool. In carriers 

 agglutinins are generally present. Normal serum may 

 agglutinate the vibrio up to a dilution of 1 in 20. 



Occurrence, of cholera-like vibrios. The bacteriological 

 recognition of cholera and of the cholera vibrio has 

 become complicated owing to the existence of pathogenic 

 vibrios which, although not identical with the cholera 

 vibrio of Koch, resemble it closely. 



The cholera-like vibrios occur in the stools, sometimes 

 with the standard cholera vibrio, and occasionally may 

 be isolated from the tissues. They form indole and 

 resemble the standard cholera vibrio in their general 

 cultural reactions. Slight differences between them and 

 the standard cholera vibrio are occasionally noticeable, 

 e.g. in morphology and in the rate of liquefaction of 

 gelatin, and the majority hsemolyse. They are commonly 

 virulent to rabbits, even in smaller dose than the standard 

 cholera vibrio, and about one-third of them are pathogenic 

 to pigeons. 



Agglutinins agglutinating the autogenous cholera -like 

 vibrio are usually either not present, or are present only 

 in small amount in the serum of the patient from whose 

 stools cholera-like vibrios alone have been isolated. Occa- 

 sionally agglutinin for the autogenous cholera-like vibrio 

 is present in fair amount, and it may be that in addition 

 to typical cholera caused by the standard cholera vibrio, 



