38 ESSENTIALS OF BACTERIOLOGY 



about death of the cell, while a few would act as an irri- 

 tant. 



Weigert's Law. When a cell is attacked by a few mole- 

 cules of toxin, it reacts by forming new side chains or recep- 

 tors, and, in accordance with the law of Weigert, always in 

 excess. Repeated injections of toxins in increasing doses 

 cause such an overproduction of receptors of the first order 

 that they are thrust from the cell and float free in the blood- 



I 



1 



Fig. 7. Graphic representation of receptors of the second order and 

 of some substances uniting with one of them: c, Cell-receptor of the 

 second order; d, toxophore or zymophorous group of the receptor; e, 

 haptophore of the receptor; /, food substance or product of bacterial 

 disintegration uniting with the haptophore of the cell-receptor (Ehrlich). 



stream. Here they can combine with toxin molecules, just 

 as when they are attached to the cell. By thus combining, 

 they prevent the toxin from reaching the cells. 



Antitoxins are specific in their action; that is, each anti- 

 toxin will neutralize only a certain toxin. Thus diphtheria 

 antitoxin will not neutralize tetanus toxin or snake venom, 



