324 PROTEIN POISONS 



Richet held that sensitizers contain a substance which 

 he called "congestin," and that this develops in the animal 

 another substance known as "toxogenin." The reaction 

 between the latter and the homologous protein on reinjec- 

 tion sets free a poison "apotoxin," which on account of its 

 effect on the nervous system, develops the symptoms of 

 anaphylaxis. Considering Richet's toxogenin a ferment, 

 we can accept this theory as essentially correct. 



Besredka taught that the sensitizer contains two sub- 

 stances " sensibilisinogen" and "antisensibilisin." On the 

 first injection the former develops in the animal body a 

 substance, "sensibilisin," and on reinjection the sensibilisin 

 and the antisensibilisin combine to form a poison which 

 acts on the nervous system. Besredka has not been able 

 to produce satisfactory proof of the existence of antisensi- 

 bilisin. His work along this line has already been referred 

 to (p. 260). 



For reasons which will become evident as we proceed, it 

 is desirable to go somewhat into detail in considering the 

 theory of Friedberger. This was first published in 1909, 1 

 and in this publication Friedberger clearly and unequivocally 

 set forth his theory. It may be known as the theory of 

 sessile or fixed receptors. The followng is an abstract of 

 the statement: On the first injection the protein finds but 

 few groups with which it can combine, and for this reason 

 it is not poisonous, even in large doses, just as happens 

 when tetanus toxin is injected into a naturally immune 

 animal. During the period of incubation the animal cells 

 develop specific receptors for the homologous protein. 

 With frequent injections at short intervals, as when the 

 object is to obtain a highly active precipitating serum, 

 the newly formed receptors are in large part cast off into 

 the blood. When a single small dose is given, as in sensi- 

 tization, less receptors are cast off into the blood, and more 

 remain attached to the cells. In this way an organism 

 relatively insusceptible to a given foreign protein is made 



1 Zeitsch. f. Immunitatsforschung, ii, 208. 



