THE BLOOD AND LYMPH AS PROTECTIVE MECHANISMS 249 



nated as "haptophore" and the poisonous portion as "toxophore." 

 A similar view has been expressed by Arrhenius and Madsen, 1 who 

 believe that the toxin possesses a weak chemical avidity for the anti- 

 toxin, the resulting reaction being similar to that occurring between 

 a weak acid and base. The medium, therefore, would embrace un- 

 combined toxin and antitoxin as well as the neutral product. It is 

 quite impossible, however, to explain the phenomena of immunity 

 in this simple manner. It has also been pointed out by Craw that the 

 neutralization of the toxin is comparable to the action which takes 

 place between absorbing membranes and certain dyestuffs. For 

 example, if a piece of filter paper is placed in a solution of fuchsin, 

 some of the dye adheres to the paper, the adhesion increasing with the 

 concentration of the solution. Furthermore, if the piece of filter 

 paper is first divided into several smaller ones which are then placed 

 in the solution separately, the absorption will be more intense than that 

 obtained with the help of the whole paper. It is also conceivable that 

 the union of the antitoxin and toxin is not exclusively a chemical 

 process, but is in part governed by physical laws. 



An explanation regarding the relationship existing between the 

 toxins and the cellular components of the body, was first made possi- 

 ble upon the basis of Ehrlich's theory pertaining to the nature of the 

 protoplasmic molecule, published in 1885. When applied to the inter- 

 action between the antitoxin and the toxin, it is generally designated 

 as the side-chain theory. 2 It is assumed that each protoplasmic mole- 

 cule possesses a central core of protein upon which the specific activities 

 of the cell depend. Branching out from this core we have a number 

 of side-chains, or "receptors," by means of which the cell is brought 

 into relation with the substances contained in the blood. An inter- 

 change of materials is effected through them which purposes the 

 substitution of the waste products by newly acquired nutritive particles. 



This process may be illustrated by the configuration given to the 

 free and combined salicylic acid group. In this case, the benzol ring 

 represents the radicle, and the COOH and OH the side-chains as 

 follows : 



OH 



C 



/\ 

 H C C COOH 



H C C H 



\/ 

 C 



I 



H 



1 Zeitschr. fur physik. Chem., 1902. 



2 Ehrlich, Collected Studies on Immunity, translated by Bolduan. New York 

 1906. 



