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Dr. W. M. Haffkine. 



different animals, so varied is the result of the application of such 

 virus from the point of view of immunity conferred by it. 



There are animals in whom the inoculation leaves no lasting effect 

 whatever. In others a very temporary immunity is created, vanish- 

 ing entirely in a few days. In other cases again, a condition appears 

 that produces the impression that, after the treatment, the animal has 

 become more susceptible to a subsequent infection than is a normal 

 animal not so treated. 



And lastly, there may be found animals in which the same virus 

 will produce a firm and enduring immunity. 



In general I believe it to be admissible that in the case of every 

 disease, and with regard to every species of animal, a form of pro- 

 phylactic treatment may be found that will produce immunity in that 

 particular case ; but that same method of treatment may or may 

 not be applicable to another animal or to another disease affecting the 

 same animal. 



It is the failure of taking into account this variation of circumstances 

 that, I believe, more than anything else has checked the success of 

 a number of experimenters. 



Immunity from Attack, and Resistance to actual Symptoms of Disease. 



The study of the anti-cholera inoculation in India has revealed a new 

 problem in the subject of prophylactic treatment. 



The particular character of cholera epidemics, which appear un- 

 expectedly, do not last, and in places where they are permanent, are 

 spread and scattered over large areas, makes the study of that disease 

 and the demonstration of the effect of a preventive treatment in its 

 case a matter of much greater difficulty than is the case in localised 

 contagious diseases, like smallpox, or in plague ; and although a large 

 amount of material has been collected already, it is desirable that 

 further observations be still added to the present ones confirmatory of 

 the results obtained. 



The information collected permits, however, already of pointing out 

 very important features in the working of the anti-cholera inoculation. 



The most extended and continuous observations on the subject were 

 organised by the Municipality of Calcutta, upon the enlightened 

 initiative of Professor W, J. Simpson, late Health Officer, and under his 

 continuous supervision, as well as my own. These observations refer 

 to the cholera stricken suburbs of Calcutta, the so-called " busties " 

 or groups of huts situated round the tanks, where rain-water is collected 

 during the monsoon. 



Some 8000 people were inoculated in those localities, and for two 

 years observations were made and the results collected as to the occur- 

 rences of cholera in the huts inhabited by the inoculated. 



