VI 



In comparing the above experiments the conclusion 

 may be drawn, that the difference in question between 

 an actively and passively immunised animal can not be 

 attributed to a change, occurring in the typhoid-serum 

 through the process of coagulation. This appears from 

 the fact, that the agglutinin producing property of a B. 

 typhos. culture is completely prevented by a transfusion 

 of a sufficient amount of agglutininholding blood. 



It is also indicated from other facts, that the agylu- 

 tinin as such exits in the organism in which it is pro- 

 duced. A culture of B. typhosus, introduced intrave- 

 nously into an actively immunised animal will be ag- 

 glutinated. This is especially striking when a great 

 amount of culture is injected; in this case the clumps 

 of agglutinated bacilli may bring about numerous emboli 

 in different organs. 



From the last two series of experiment it is obvi- 

 ous, that the mere presence of introduced agglutinin 

 is not sufficient to prevent an "agglutinin curve", but 

 that the amount of it plays a great role. It seems, 

 that is it not only the absolute amount of agglutinin 

 injected, and not the titer of the serum obtained after 

 this injection, which is of importance. From our small 

 experience we have got the impression, that it is rather 

 the relative increase, which is the main factor. 



It is obvious, that this circumstance renders the 

 conclusions drawn from a few experiments very unre- 

 liable, and it has made it very difficult for us to continue 

 our experiments in the line, we intended to follow. 



We had seen, that a fraction of the blood, transfu- 

 sed into another^animal, prevented "agglutinin curve" 

 while a such one arose in the producing animal, con- 

 taining much more agglulinin. 



Our plan then was on a number of actively immuni- 



37 



