166 



PRINCIPLES OF VETERINARY SURGERY 



drogen unite to six atoms of carbon. The chemical formula 

 of benzene with its various side-chains may be graphically 

 compared with a cell and its receptors . 



Fig. 19. 



Receptors of the First Order, are represented in Fig. 19, I., at a, being attaclied to tlie cell, 

 molecule beneatti. Tlie portion e represents the heptophorous complex, whilst b represents a 

 toxin molecule, which possesses a haptophorous c and toxophorous d group.- This represents 

 the union ol 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. 19, II., in which e represents the 

 haptophorous, and f^the zymophorous group of the complex, /"being the food-molecule with 

 which it enters into combination. Receptors of this order are possessed by agglutinins and 

 precipitins. Tlie digestive cell, or the antibody present in the serum in this case, possesses 

 one haptophorous and one zymophorous group. 



Receptors of the Third Order, are represented in Fig. 19, III., e being the haptaphorous 

 group, 5-the complementophile group of the complex, k tho complement with its haptophorous 

 A and zymotoxic z group ; whilst / represents the food-molecule which has become linked to 

 the receptor. Such receptors are found in hiEmolysins, bacteriolysins and other cytolysins, 

 the union with these cellular elements being effected by means of the immune-body, this per- 

 mitting the complement to act as a digestive ferment. — Ntttiall, 



The side-chains, or receptors, fulfil various accessory 

 functions, but serve especially for the nutrition of the cell. 

 A molecule of assimilable substance, coming in contact with 

 the cell protoplasm, is absorbed by combining with one of 



