366 SPECIFIC MICRO-ORGANISMS 



microscopic field in the agglutination preparations warrants posi- 

 tive diagnosis. ^ 



Similar principles are followed in attempting to find cholera 

 germs in drinking water. A solution of pepton 100 grams, salt 

 100 grams, potassium nitrate i gram and sodium carbonate 2 

 grams in distilled water 1000 c.c. is prepared, filtered, distributed 

 in 10 flasks each of 1000 c.c. capacity, and sterilized. To each 

 flask containing 100 c.c. of this sterile solution, one adds about 

 900 c.c. of the suspected water and incubates the mixture at 37° C. 

 for six to eight hours. Subcultures and microscopic preparations 

 are made from the surface films and any curved bacteria observed 

 are tested as described above. 



The prophylaxis of cholera no longer rests upon the enforce- 

 ment of quarantine regulations, for it is now known that conval- 

 escents may carry the vibrio alive in their intestines for many 

 weeks. The exclusion of the disease depends upon the bacterio- 

 logical examination of every person coming from infected regions 

 before he is allowed to land at his destination. A water-supply 

 system well protected from fecal pollution is an element of safety 

 for any community. The Hambyrg epidemic of 1892 illustrated 

 this point. The unfiltered water taken from the Elbe near the 

 harbor carried the infection and distributed it throughout the city 

 of Hamburg. In the presence of an epidemic the best protection 

 against contact infection is provided by immunization. 



Ferran in 1884 first induced immunity to cholera in animals 

 and in man by the subcutaneous injection of living cultures. 

 Haffkine improved the method so as to make it reliable. He 

 employed a first vaccine of attenuated virus and a second vaccine 

 of high virulence with an interval of five days between the injec- 

 tions. Kolle introduced the use of killed cultures, employing a 

 single injection of 2 mg. of growth from an agar culture suspended 

 in I c.c. of salt solution and killed by heating an hour at 58° C. 

 As a result of this treatment the agglutinins, bacteriolysins and 



1 Krumwiede, Pratt and Grund, Journ. Inject. Diseases, 1912, Vol. X, pp. 

 134-141. 



