146 IMMUNE SERA 



incubation. Here the second injection comes at a 

 time when the accumulation of antibodies is at its 

 height. It has been claimed that this explains the 

 cases of sudden death in humans following injec- 

 tions of serum, but investigation shows that most 

 of these deaths occurred after but a single injection 

 of serum. Moreover in most of them such conditions 

 as status lymphaticus sufficed to explain the fatal 

 ending. 



This theory has found some experimental con- 

 firmation from the work of Vaughan and Wheeler, 

 who have been able to prepare a number of split 

 products from the proteid molecule, some of which 

 in animals give- rise to a symptom complex not 

 unlike that of typical anaphylaxis. 



Gay and Southard hold a somewhat different 

 view. According to them the " horse serum con- 

 tains a substance, anaphylactin, which is not neu- 

 tralized, and is eliminated from the body with great 

 slowness. When a normal guinea pig is injected 

 with a small amount of horse serum, the greater 

 part of its elements are rapidly eliminated; the 

 anaphylactin, however, remains and acts as a 

 constant irritant to the body cells, so that their 

 avidity for the other assimilable elements of horse 

 serum which have accompanied the anaphylactin 

 becomes enormously increased. At the end of two 

 weeks of constant stimulation on the part of the 

 anaphylactin, and of increasing avidity on the part 



