202 A MANUAL OF BACTERIOLOGY 



in the blood or in the tissues, usually in both ; all that is 

 essential is the presence of the requisite amount of anti- 

 body. The cells will take up a certain amount of the 

 anti-body, and any excess remains in the blood. 



A striking analogy exists between peptone poisoning 

 and anaphylactic shock ; protein cleavage products may 

 be the substances concerned in the production of the 

 latter. 



Gay and Southard believe that every antigen consists 

 of two distinct portions and suppose that during sensi- 

 tisation one of these, a toxic portion, is eliminated, and 

 that the other, the sensitising, is retained. The latter 

 acts in some way upon the body cells, rendering them 

 capable of being affected by the toxic moiety of the 

 antigen, whereas previously they are incapable of being 

 so affected. This, however, does not explain humoral 

 anaphylaxis. 



Besredka also assumes that there are two distinct 

 elements in antigen, one thermostable and having the 

 properties of an antigen (see p. 179), which he terms 

 " sensibilisogen," and which on injection produces its 

 anti-body, " sensibilisin." The other substance is ther- 

 molabile, and is termed " anti-sensibilisin," and com- 

 bines with sensibilisin whenever it meets with the latter. 

 Sensibilisin is particularly fixed by the cells of the nervous 

 system, and, according to Besredka, it is the violent 

 reaction between anti-sensibilisin and sensibilisin in the 

 nerve tissues which causes the serious disturbance cha- 

 racteristic of anaphylaxis. When, therefore, a small dose 

 of serum (^-Jr)"^ c.c.) is administered, the sensibilisogen 

 slowly forms sensibilisin. If a second dose of serum is 

 given twelve days or more after the first injection, the 

 anti-sensibilisin in it combines with the sensibilisin formed 

 by the first injection, and disturbance results. Ansesthe- 

 tisation prevents the symptoms of anaphylaxis because 



