214 MODERN BIOLOGIC THERAPEUSIS 



pupil of Pasteur. Under the influence of the 

 French school and its endeavors to immunize 

 with living attenuated microorganisms, Ferran 

 applied similar methods to cholera by inocu- 

 lating with small quantities of living broth cul- 

 tures of the cholera spirilla. The method which 

 Haffkine worked out, some years after Ferran 's 

 experiments, also depended upon the injection 

 of living cultures; but Haffkine attempted to 

 produce two separate vaccines, one attenuated, 

 the other enhanced in virulence. Beginning his 

 work as early as 1893, Haffkine and others vac- 

 cinated as many as 40,000 people in India. On 

 the whole, the results obtained were very en- 

 couraging. 



According to Zinsser, we have reason to be- 

 lieve that immunization with killed cultures 

 may produce results fully as efficacious. At 

 present it is not to be expected that we could 

 produce by active artificial immunization an im- 

 munity as permanent as that which results from 

 an attack of the disease. Later on, Kolle recom- 

 mended the injection of killed cholera spirilla, 

 and good results with Kolle 's method have been 

 reported from Japan. Kolle 's method is more 

 practicable. Two doses of the vaccine are given 



