156 COLLECTED STUDIES IX IMMUNITY. 



increase is usually very great and only rarely slight. The injection 

 of agglutinated typhoid bacilli, provided that attention is paid to a 

 sufficient saturation with agglutinin, is frequently followed by no 

 reaction, often by a slight reaction, and rarely by a marked increase 

 of the agglutinating value. This reacting power depends on the 

 individuality of the animal and stands in no relation to the original 

 agglutinating value, nor can it be influenced artifically. Furthermore, 

 as we learned from a special experiment, it is immaterial whether 

 the immune serum used to agglutinate the typhoid bacilli is derive'd 

 from the same or from another animal species. 



The explanation of these facts is not difficult provided one pro- 

 ceeds on Ehrlich's theory. According to this the agglutinin consists 

 of thrust-off cell-receptors. As a result of their seizure by the 

 bacterial receptors they have been produced in excess and give 

 off to the circulation. They, therefore, possess a definite relation 

 to the corresponding bacterial receptors. Hence when we fully 

 saturate typhoid bacilli with agglutinin, we cause the bacterial 

 receptors to be occupied, and are then as little able to cause a reaction 

 with these bacteria as we are to cut with a sword in its scabbard. 



If then, in spite of this, certain animals react to such "occupied" 

 typhoid bacilli, we shall have to assume that these animals possess 

 the power to dissolve the combination of agglutinin and bacterial 

 receptor and thus set the latter free. 



This action, however, never proceeds to the full extent. 



Incomparably more important, and, as it appears to us, explicable 

 only with the aid of Ehrlich's chemical views, is the main phenomenon, 

 that in many animals no reaction whatever follows the inoculation of 

 agglutinated typhoid bacilli; that therefore in many cases it is 

 possible to dispose of the bacterial group giving rise to the agglutinin, 

 by causing this group to be occupied by the corresponding agglutinin. 



SUBSEQUENT NOTE. 



R. Pfeiffer and Friedberger, 1 through recent experiments on cholera vibrios 

 and cholera amboceptors, have obtained results which are in gratifying acrord 

 with those obtained by v. Dungern, M. Neisser and Lubowski, and Sachs. 2 

 In earlier experiments R. Pfeiffer 3 had found that the bacterial substance 

 dissolved in the peritoneum through the influence of the cholera immune serum 



1 R. Pfeiffer u. Friedberger, Berl. klin. Wochenschr., 1902, No. 25. 



2 See the following article. 



3 R. Pfeiffer, Deutsche med. Wochenschr., 1901, Nos. 50-51. 



