PRINCIPLES OF VETERINARY SURGERY 



167 



the side-chains much the same as a key fits into a lock. In 

 this way it enters the cell itself and becomes a chemical 

 part of it. A side-chain combining with a simple substance 

 such as toxin molecule, Ehrlich calls a uniceptor; one com- 

 bining with a complex substance he calls an amboceptor. 

 These receptors have a great affinity for the various sub- 

 stances maintaining the life of the cell. Under normal con- 

 ditions these receptors seize nutritive molecules which 

 serve as food; while under special conditions these receptors 

 lay hold of complex molecules of albuminoid substances 

 like toxins, and instead of combining with a molecule which 

 nourishes the cell, unite with one which poisons the cell. 



According to Ehrlich's theory, the toxin molecule con- 

 tains two anatomic groups, — one which combines with a 

 receptor of the cell, the haptophore, and one which poisons 

 the cell, or the toxophore. This is illustrated as follows : 



Toxophore or pan which poisons. 



.-Haptophore or pan which combines 

 )g" \ with the receptors. 



*.SWe-chains or receptors. 



Fig. 19 a. 

 Unless a cell has receptors that fit the haptophore group 

 of the loxin molecule, they will not combine. They will lie 



