152 



COLLECTED STUDIES IN IMMUNITY. 



The next question was whether rabbits really react at all to 

 injections of agglutinated typhoid bacilli; in other words, whether 

 the normal agglutinating value possibly present is at all increased 

 by injections of agglutinated typhoid bacilli. The result was sur- 

 prising, as is seen in Table VI. For while in four animals no increase 

 occurred, in two others there was a very slight increase, and in four 

 more the increase, though distinct, was insignificant in comparison 

 with that in six animals injected with non-agglutinated typhoid. 



TABLE VI. 



NOTE. 1 mass culture equals about 12 agar cultures. 



With this the main portion of the question had been answered; 

 for these experiments already showed that the injection of agglutinated 

 typhoid bacilli exerts an action which quantitatively is different 

 from that following the injection of non-agglutinated bacilli. Never- 

 theless even the agglutinated bacilli, although their injection is 

 often wholly without effect, in many cases still exert a stimulus on 

 the formation of agglutinins even though in a slight degree. This 

 is due to individual peculiarities of the animals employed, and these 

 we have not thus far been able to recognize in advance. The natural 

 assumption that animals which already normally possess agglutinins 

 react more readily to the injection of agglutinated typhoid bacilli 



