242 POPULAR SCIENCE MONTHLY. 



result was that for two years after inoculation, including the periods 

 of incomplete protection, there was a reduction in mortality of 72.47 

 per cent among the inoculated; or in other words, in houses in which 

 inoculations were performed and in which cholera subsequently oc- 

 curred there were, even from the day of inoculation, before the full 

 effect of it could be produced, eleven deaths among the non-inoculated 

 to only three among the inoculated. Eight lives out of every eleven 

 were saved. 



At the end of my first cholera campaign, in August, 1895, there 

 were altogether 31,056 natives of India, 125 Eurasians, 869 Euro- 

 peans of the civil population, 6,627 native officers and sepoys, and 

 291 officers with 3,206 men of the British troops stationed in India, 

 in all 41,787 people, who had submitted to inoculation. Observa- 

 tions instituted among them, especially among prisoners, soldiers and 

 coolies in tea estates, with regard to whom detailed records could be 

 kept, went to confirm the results as detailed above. In order to 

 lengthen, if possible, the period of immunity, the plan was formed of 

 inoculating stronger vaccines and in higher doses. The inoculations 

 are now carried on in a Government laboratory, in Purulia, Bengal, 

 chiefly among the people emigrating to the cholera districts of Assam, 

 and there is no doubt that in the course of time a marked effect upon 

 the prevalence of cholera in those districts will be produced and val- 

 uable theoretical data will be obtained. 



There was one noticeable feature about the results of the inoculation 

 against cholera which early attracted my attention, and this was that 

 while the number of attacks and the absolute number of deaths was 

 strikingly influenced by the operation, the" proportion of deaths to those 

 attacked did not appear to be changed. The case incidence was effec- 

 tively checked, but the 'case mortality' was not reduced. The inocula- 

 tion diminished the chances of an attack of cholera — that is, the 

 chances of the cholera virus penetrating into the tissues of a man; but if 

 it so happened that the patient was attacked and the virus found an 

 entrance and started growing in the system notwithstanding the in- 

 oculation, the latter would not assist in mitigating the severity of the 

 symptoms or reducing the fatality of the disease. In analyzing this 

 result further, it seemed to me permissible to assume that the vaccine 

 protected against the cholera microbes themselves, but did not protect 

 against their poisonous products, which are the cause of the actual 

 symptoms. 



This interpretation of the facts found support in a- set of laboratory 

 experiments by Professor Pfeiffer and Dr. Kolle, of Koch's Institute, in 

 Berlin, who showed that the" blood serum of animals and persons in- 

 oculated with the cholera vaccine, as practiced in India, acquired an 



