196 CLINICAL BACTERIOLOGY. 



sodium chlorid are kept in readiness in sterilized solutions, 

 and, for instance, 5 cu. cm. and 2.5 cu. cm. of 20 per cent, 

 solutions are added respectively to 100 cu. cm. of water. 

 After testing its alkalinity, the mixture is placed in the 

 thermostat, and it is then treated in exactly the same way as 

 has been described for the peptone -culture. On micro- 

 scopic examination of the surface of the peptone after eight, 

 ten, fifteen, and twenty hours, curved bacteria that closely 

 resemble the comma-bacilli are found in many samples of 

 water. It can not be too strongly emphasized, however, that 

 such a discovery is alone not demonstrative, if the vibrios 

 are derived directly from the feces of a sick human being. 

 In examinations of water it is still further an unavoidable 

 postulate that plates of gelatin or of agar be made with the 

 fertilized material from the surface. If upon these are 

 found colonies that correspond in appearance with cholera- 

 colonies, it is not yet demonstrated that they are true 

 comma-bacilli and not merely similar microbes, of which a 

 number have already been described. It is then necessary 

 to make pure cultures, and these are to be identified by 

 means of the indol-reaction, by experiments on animals, 

 and especially by means of Pfeiffer's and Gruber's reactions 

 (pp. 62, 63, 187, 188). 



Disinfection and Prophylaxis. Every cholera-patient 

 must be isolated at once. Feces and vomited matters, as well 

 as all materials soiled therewith, should be most thoroughly 

 disinfected. The details of disinfection are given in the Ap- 

 pendix. Those who come in contact with the patient should, 

 further, be watched with care, and their dejections should be 

 examined for comma-bacilli. Personal prophylaxis extends 

 to the maintenance of the digestive tract in a state of health 

 (avoidance of all dietetic errors), and the protection against 

 contamination of all articles of food (only boiled water should 

 be drunk, etc.). The general prophylaxis concerns itself 

 with the purification of the water-supply by means of suit- 

 able filtration, with the protection against contamination of 

 waterways, and, above all, with the prevention of importation 

 of the disease from abroad. The pilgrimages to Mecca are 

 under the scrutiny of the International Sanitary Commission 

 at Alexandria. Cholera prevails frequently among the 

 pilgrims, and upon the slightest suspicion the pilgrim-ships 

 must be subjected to quarantine before being permitted to 

 pass through the Suez Canal. 



