494 IMMUNOLOGY 



stedt and Meade (1936) offer confirmatory evidence that the 

 anaphylatoxin previously described by Dragstedt et al. is histamine. 



Farmer (1939) reports that the injection of histamine into 

 serum-sensitized guinea pigs renders the uterine horns less sensitive 

 to antigen. 



Sherwood, Stoland and Nelson (1941) have shown that the 

 liistamine reaction in turtles resembles the anaphylactic response 

 and that turtles, unlike dogs, cats and rabbits, become refractory 

 to histamine following recovery from the intracardiac injection of 

 liistamine. It is yet to be determined whether the refractory state 

 is due to the liberation of histaminase. 



Another report which points to the similarity beween histamine 

 and anaphylactic reactions is given by Andrus and Wilcox (1939). 

 They report that the response of the coronary artery of hearts per- 

 fused witli histamine was the same as tlie anaphylactic response. 



In 1930 Best and McHenry demonstrated a histamine inactivat- 

 ing substance in horse lung and later in beef lung, liver and kidney. 

 They noted that the inactivating substance was specific for his- 

 tamine and have designated it histaminase. The early work on 

 histaminase appeared to show that the inactivation of histamine oc- 

 curred only in vitro but subsequent work by Karady and Browne 

 (1939) indicates that inactivation occurs in vivo. They report 

 that histaminase injected into guinea pigs fifteen minutes before 

 the injection of a lethal dose of histamine prevented histamine 

 shock in a majority of the animals. They also report that anaphy- 

 lactic shock in sensitized guinea pigs is almost entirely prevented 

 by an injection of histamine prior to the administration of the 

 shock dose of antigen. 



Since it would appear from the evidence submitted that either 

 theory may be adopted to explain the anaphylactic response, it 

 might be profitable to extend somewhat the discussion of each. 



Further Discussion of the Physical Theory. — 

 1. The physical theory assumes that physical changes occur 

 either at the cell surface or within the cell and that such physical 

 change supplies the toxic stimulus. It would seem that neither 

 of these assumptions can be proved directly by experimental ob- 

 servation although they are in harmony with our present chemi- 

 cal and physiological concepts. 



