xvi] VIBRIO AND SPIRILLUM 449 



natural infection with cholera per os. It ought to be 

 further stated, however, that according to the observations 

 of Wassermann and Pfeiffer (Zeitschr. f. Hygiene mid Infect. 

 vol. XIV., and according to my own observations (Reports 

 of the Medical Officer of the I^ocal Government Board 

 for 1893 and 1894), such intestinal protection of guinea- 

 pigs is not by any means uniformly observed even after 

 intraperitoneal active immunisation. R. Pfeiffer, as a result 

 of his recent experiments, finds that guinea-pigs passively 

 immunised by the intraperitoneal injection of " cholera 

 serum '' are still susceptible to intestinal infection after 

 Koch's method. 



But, be this as it may as regards the guinea-pig, 

 Haffkine has in India, during 1894 and 1895, made a large 

 number of double and treble vaccinations, and has collected 

 a large body of statistics as to cholera-vaccinated persons 

 that have been exposed to cholera in India living in the 

 same locality and conditions side by side with non-vaccinated 

 persons. The latest statistics published in India, and in the 

 British Medical Journal, during the last months of 1895 by 

 medical men who had assisted in these vaccinations and 

 had observed the results are of a most encouraging nature ; 

 when seeing it stated that in a large body of unvaccinated 

 persons of a given locality (tea plantations) the incidence of 

 attacks is enormous, and in an equally large body of vac- 

 cinated persons living side by side and under the same 

 conditions with the former the incidence of attacks is 

 incomparably smaller, in fact in some of the latest statistics 

 is very small indeed as compared with that in unvaccinated 

 persons— that is to say, while of unvaccinated persons the 

 disease kills off many, of the vaccinated persons only few — 

 seeing all these statements one cannot help arriving at the 

 conclusion that the protective inoculations practised by 



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