AGGLUTININS 43 



colon bacillus, and some protoplasm C, common 

 perhaps to some other bacterium. In the case of 

 the colon bacillus, protoplasm D is specific, i.e., 

 possessed only by this bacillus, while B is common 

 to it and the typhoid bacillus, and E common to 

 colon and dysentery bacilli. 



By immunization with the typhoid bacillus we 

 would obtain a serum containing agglutinins against 

 protoplasm A, B, and C. By virtue of this the 

 serum would exert some agglutinating power also 

 on colon bacilli. On extracting such a serum with 

 the typhoid bacilli, all the agglutinating power would 

 be lost, that for the typhoid bacilli as well as that 

 for the colon. On extracting this serum with the 

 colon bacilli we would remove the agglutinating 

 power for these bacilli, but leave the specific agglu- 

 tinating power on typhoid bacilli. 



Formation of the Agglutinins According to the 

 Side-Chain Theory Receptors of First, Second and 

 Third Order. Ehrlich's theory as outlined in the 

 preceding chapter offers a ready explanation for the 

 development of these bodies. Certain peculiarities 

 of the agglutinins require merely a slight elabora- 

 tion of detail in order to be clearly understood. 

 According to Ehrlich the prime function of the side 

 chains of a cell is to provide for the nutrition of the 

 cell. Obviously the simplest mechanism for this 

 purpose will be a side chain which merely anchors 

 the food molecule, leaving the digestion entirely to 



