450 MICRO-ORGANISMS AND DISEASE [chap. 



Haffkine in India with cultures of cholera vibrio have had 

 positive results, and further that these observations form a 

 strong link in the chain of evidence that the cholera vibrio 

 is the cause of cholera. The evidence that Koch's vibrio is 

 the microbe of Asiatic cholera, and as such forms an 

 essential— though not the only— factor in the production 



Fig. iSo. — Plate Cultivation in Gelatine of Vibrio Finkler — Prior, 

 incubated at 20°c. forty-eight hours ', the colonies are round, lique- 

 fied, turbid, so.me isolated, others confluent. 



Natural size. 



of cholera asiatica— disposition, locality, season, being other 

 factors — is then a chain in which the individual links taken 

 separately are open to criticism, but when all are taken to- 

 gether — notably : the diagnostic value of the cholera vibrio 

 for cases of Asiatic cholera, the capability of the vibrio to pro- 

 duce powerful toxin, the result of experiments on ingestion of 

 cultures of cholera vibrio on human beings, the immunising 



