SIDE CHAIN THEORY OF EHRLICH. 



affinity for the invading haptophores. These 

 latter groups, the detached or cast off receptors, 

 are the antitoxins. 



When one seeks to compare the "side-chain 

 theory of Ehrlich" with the "theory of phago- Ehrlich's _ 

 cytosis of Metchnikoff," one finds but little in Versus Theory 

 common. Notwithstanding this fact, it is °* Metchnikoff. 

 rather striking that there are so few contradic- 

 tions. Ehrlich's theory is one built upon chem- 

 ical lines. That of Metchnikoff is founded upon ■ 

 biological principles. Each in a measure relates 

 to nutrition. Metchnikoff only carries food 

 substances into contact with the digestive 

 ferments contained in the cell and there he 

 leaves them. Ehrlich goes farther and teaches 

 us how nutritive matter enters into and 

 becomes a part of the protoplasm. Metchnikoff 

 does not appear to concern himself with the 

 structure of toxins, nor with the way in which 

 they injure the cell. Ehrlich points out both of 

 these factors. Metchnikoff believes that anti- 

 toxin is produced by phagocytic action on the 

 toxin. Ehrlich presents an opinion entirely 

 opposed to this. He believes antitoxins to be 

 produced by the cell itself. 



Both believe that amboceptors (fixiators) 3y[gt^^J„J^^,ff,s 

 become extra-cellular in the blood. Metchnikoff Conception of 

 asserts that complements are substances which veSL^ttfrt* 

 are produced by the phagocytes and that they of Ehrlich. 

 are found in the plasma or serum of the blood, 

 167 



