22o 



ANTITOXINS 



the toxin, and rendering it practically harmless. Antitoxins, therefore, 

 are nothing more than these cast-off receptors, which have a specific affinity 

 for their toxins (Fig. 67). 



As Adami has pointed out, it is probable that the toxins exist for 

 some time within the cell, not as part and parcel of the cell, but as a 

 stimulating agent that causes the cell to develop the habit of producing 

 the specific receptors. The mere union of toxin with a receptor, causing 

 it to fall off, and being followed by nature's mode of repair, with the 

 formation of an excess of receptors and no further stimulation, is hardly 

 sufficient to explain the enormous activity of the cells. 



FIG. 67. THEORETIC FORMATION OF ANTITOXINS. 



The central white area represents a molecule of a cell; the shaded portion repre- 

 sents the cell itself; the surrounding area represents the body-fluids about the cell. 



r, a receptor of the molecule (first order] ; A, overproduction of receptors, which 

 are being cast oft 7 ; A 2 , a cast-off receptor free in the body-fluids now an antitoxin; 

 A 3 , a molecule of antitoxin combination with a toxic molecule T 3 . A 3 , a cast-off 

 receptor still within the parent cell; T, a toxin molecule in combination with the re- 

 ceptor of a cell molecule; T 2 , a toxin molecule free in the body-fluids; T 3 , a toxin 

 molecule in combination with antitoxin; T 4 , a molecule of toxoid (toxophore group 

 lost). 



That antitoxins may be produced locally was illustrated by the ex- 

 periment of Romer with abrin. This substance has a peculiarly power- 

 ful effect upon the conjunctiva. By gradually immunizing the right 

 conjunctiva of a rabbit with increasing doses, it was shown that, after 



