﻿318 STRONG. 



than did the avirulent one. At the time of the publication of these 

 experiments I stated that "these conclusions apply to the two strains 

 of cholera spirilla employed in the foregoing experiments. Whether 

 they will also hold good with other strains of this spirillum or for micro- 

 organisms in general must be decided by further experimental work." 



Wassermann, 119 in studying the question with typhoid bacilli found that two 

 strains of the organism which possessed a greater immunizing power and a 

 greater power of binding amboceptors than a third strain, were nevertheless less 

 virulent. From these experiments one would conclude that the immunizing power 

 depended rather upon the binding power of the organism than upon its virulence. 

 During the past year Meinicke, Jane and Flemming, 1 ^ have performed careful 

 and much more extensive experiments with cholera spirilla, their investigations 

 relating to the question of virulence with reference to the power to bind 

 amboceptors and to immunize. While in some instances they found that a 

 virulent cholera culture was able to bind more amboceptors than an avirulent 

 one, in the great majority of their experiments they were able to show that 

 the binding power was independent of virulence, since in many instances the less 

 virulent culture bound a greater number of amboceptors than the more virulent 

 one. 



Their experiments referring to the question of the relation between 

 virulence and immunizing power are not numerous, as the authors 

 admit. This seems to me to be unfortunate, for by means of their 

 methods of examination and the large number of strains which they 

 studied they were in a position to solve this problem conclusively. In 

 one experiment they were able to show that, in one instance at least, a 

 much attenuated culture was in a rabbit able to give rise to a serum of 

 higher value than resulted from the use of a very virulent culture. 

 Nevertheless, it would appear that an individual variation in immunity 

 in the rabbit immunized with either the virulent or the avirulent 

 organism, might also account for the difference in immunity obtained, 

 and therefore it would appear to be injudicious to draw decided con- 

 clusions from this one result. Moreover, it may be seen in the table 

 which Meinicke, Jaffe and Flemming compiled, and the fact is also 

 emphasized in the text of their article, that with the small doses in- 

 oculated, 0.1 and 0.01 oese, there was very great variation in the value 

 of the sera produced in the different rabbits. Thus, of two animals, 

 each inoculated with 0.01 oese of the same culture, one furnished a 

 serum showing a bactericidal value of 1 : 400 and the other of 1 : 1,000. 

 However, it must be admitted that the experiments of these authors not 

 only show that with the cholera organism binding power may be inde- 

 pendent of virulence but they also suggest very strongly, if they do not 

 prove conclusively, the fact that the immunizing power also may be 

 independent of virulence. 



119 Festschrift Robert Koch (1903), 503. 



1!a Ztsdhr. f. Hyg. u. Infectionskrank., Leipz. (1906), 52, 416. 



