﻿REPORT ON CHOLERA IN MANILA. 431 



measured quantity of vaccine and a correlation obtained from this weight 

 and the number of bacteria as estimated by the living and dead count- 

 ing methods. Even by all these methods it was impossible finally to 

 arrive at an accurate standardization such as they apparently desired. 



In my opinion these experiments performed in the standardization 

 of either typhoid or cholera prophylactic are supei'fluous and unnecessary. 

 The most practicable and accurate method 1 have been able to devise 

 for the standardization of a prophylactic of this nature is the determi- 

 nation of the degree of immunization within certain limits which will 

 usually be produced by approximately equal quantities of it in an 

 animal. Evidently, exactly the same amount of immunity in a series 

 of inocidated animals is practically never produced even though the 

 dose injected is exactly the same, owing to the natural individual 

 variations in the immunity of the animals. 



Having determined upon an arbitrary unit of immunization and upon 

 the minimum number of units of immunity a given volume of the 

 vaccine must usually produce in animals, so that the inoculation of the 

 same amount will give rise to the production of a satisfactory quantity 

 Of immune bodies in a few human beings, it is only necessary always 

 to employ for man the amount of vaccine which will give rise in the 

 animal to at least the minimum determined number of units of im- 

 munity. Since individual variations in immunity in human beings are 

 so marked, it probably does not make any practical difference whether 

 one individual is inoculated subcutaneously with a few hundred or 

 perhaps even a thousand more killed organisms than is another one. 

 Thus, while for adults the regular dose of the extracted prophylactic we 

 employ is 2 cubic centinleters (which must give rise to at least 10,000 

 units of immunity in a rabbit), nevertheless, the results obtained in 

 human beings inoculated with the same lot of prophylactic and with 

 the same dose were surprisingly variable. Moreover, they conclusively 

 demonstrated that nothing of practical importance was to be gained in 

 attempting to inoculate each individual of a large number of people in 

 a community with exactly the same quantity of receptors. I have ob- 

 served two individuals, each inoculated with the same dose of the same 

 fluid prophylactic, one of whom developed forty times as great a quantity 

 of antibodies as the other. Such variations in the immunity produced in 

 human beings after inoculation are not uncommon. 28 The same condi- 



28 Agglutinins do not invariably develop in the blood sera of human beings 

 inoculated either with our prophylactic or with the living cholera organism. 

 Two physicians were each inoculated with 2 cubic centimeters of the same lot 

 of our prophylactic. After ten days the blood serum of one showed an agglu- 

 tinative reaction in a dilution of 1 : 700, while that of the other gave practically 

 no agglutinative reaction. At about the same time I was inoculated with 3 

 oesen of the living cholera organism, and although a very marked local and 

 general reaction was obtained, my blood serum ten days later showed practically 

 no agglutinative reaction against the cholera spirillum. 



