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PASTORAL AND AGRICULTURAL BOTANY 



the haptophore groups to the cells. These excessive receptors find their 

 way into the blood where they combine with the enzyme, or toxin, so 

 that it cannot enter into combination with the cells. To emphasize this 

 point, the receptors eliminated by toxin absorption are not, therefore, 

 simply reproduced in the same quantity in which they are lost, but 

 are reproduced in excess of the simple physiological needs of the cell. 

 Continuous and increasing dosage with the poison, consequently, soon 



.TOXOPHORE ? 

 * HAPTOPHORE 

 RECEPTOR 



FIG. 3. Diagram showing body cell molecule, cell receptors with linkage for toxin 

 molecule with a binding group (haptophore) and a toxic group (toxophore). The 

 receptors produced in excess by the stimulation of the body cell become the antitoxin 

 molecules which are set free into the blood and then unite, as shown in the diagram, 

 with the toxin molecules by means of their haptophores. The free antitoxin molecules 

 thus unite with the poison molecules in the blood and thus protect the body cells. 



leads to such excessive production of the particular receptive atom-groups 

 that the cells involved in the process become overstocked and cast them 

 off to circulate freely in the blood. These freely circulating receptor atom 

 groups with specific affinity for the toxins used in their production repre- 

 sent the antitoxins. These, by uniting with the poison before it can 

 reach the sensitive cells, prevent its deleterious action (Fig. 3). The 

 theory of Ehrlich, in brief, then, depends upon the assumptions that toxin 



