12 



EhrlicNs Theory 



Fig. 2. 



Receptors of tlic First Order, are represented in Fig. 2, I., at a, being attached to the 

 cell-molecule beneath. The portion e represents the haptophorous complex, whilst h 

 represents a toxin molecule, which i^ossesses a haptophorous c and toxophorous d group. 

 This represents the union of toxin and antitoxin, or ferment and antiferment, the latter 

 possessing but one haptophorous group, the union between antibody and the toxin or 

 ferment being direct. 



Receptors of the Second Order, are represented at c, in Fig. 2, II., in which e represents 

 the haptophorous, and d the zymophorons group of the complex, / being the food-molecule 

 with which it enters into combination. Eeceptors of this order are possessed by agglutinins 

 and precipitins. The digestive cell, or the antibody present in the serum in this case 

 possesses one haptophoi'ons and one zymophorons group. 



Receptors of the Third Order, are represented in Fig. 2, III., e being the haptophorous 

 group, g the complementophile group of the complex, U the complement with its hapto- 

 phorous h and zyniotoxic z group ; whilst /' represents the food-molecule which lias become 

 linked to the receptor. Such receptors are found in haemolysins, bacteriolysins and other 

 cytolysins, the union with these cellular elements being effected by means of the immune- 

 bf>d}', this permitting the complement to act as a digestive ferment. 



