﻿REPORT ON CHOLERA IN MANILA. 419 



From the subcutaneous inoculation of rabbits with 5 cubic centimeters 

 of this prophylactic containing the receptors which could be extracted 

 from 40 oesen of the same strain, sera were obtained with an aggluti- 

 native value of from 1 : 500 to 1 : 600 and a bactericidal one in from 0.14 

 to 0.1 of a milligram. Animals have been found to retain these immune 

 bodies in their sera for as long a period as one year. 



A brown powder was obtained by evaporating the prophylactic to dry- 

 ness in a vacuum. This was placed in sealed tubes and when desired 

 for use redissolved in saline solution. The intravenous inoculation of 

 rabbits with from 3 to 10 milligrams of this redissolved powder furnished 

 sera of an agglunative value of from 1 : 50 to 1 : 100 and a bactericidal 

 one of from 2.5 to 0.25 milligram. These sera were obviously of much 

 lower value than were those which resulted from the inoculation of the 

 prophylactic before evaporation. 



In man after the subcutaneous injection of 2 cubic centimeters of the 

 prophylactic, sera showing agglutinative values of from 1 : 40 to -1 : 600 

 and bactericidal ones of from 1 to 0.25 milligram were obtained. 



The advantages which this prophylactic seems to possess over other 

 forms of anti-cholera inoculation are: 



First, there is practically no local reaction or only a slight one after 

 its use, the irritating oxidizing substances which existed in the bodies 

 of the bacteria and which have nothing to do with the immunizing 

 substances, having been removed. 



Second, we therefore are able to inject an amount of these immunizing 

 substances which is from fifteen to thirty times as great as would be 

 practicable if either the living or killed bacteria were inoculated. Both 

 Haffkine and Murata in their extensive inoculations in human beings 

 injected from 2 to 4 milligrams of culture. In our human inoculations 

 the immunizing substances extracted from about 60 to 70 milligrams of 

 culture are inoculated, hence a higher immunity is obtained by this 

 procedure. 



Third, the prophylactic may be sealed in flasks and stored ready for 

 use and it preserves its immunizing properties for at least a year. 



The great disadvantage which the method possesses is that each step 

 of the manufacture of the prophylactic must be carried on with great 

 care. It is obvious that the product which we recommend and employ 

 is far more difficult to prepare than is either a simple suspension of the 

 killed or of the living cholera organism. A well-equipped laboratory 

 and trained assistants are necessary for its manufacture. However, it 

 is equally clear that a higher immunity against cholera infection can be 

 obtained by a single injection of this prophylactic than by single inocula- 

 tions of either the killed or living organisms. The reasons for this have 

 already been emphasized. 



Therefore, it has been shown that it is easy to produce in man a 



