CELLULAR ANAPHYLAXIS 201 



cerebral and intravenous injections, next intramuscular, 

 then intraperitoneal, intrapleural and subcutaneous, and 

 finally intrathecal. 



A theory to explain all the phenomena of anaphylaxis 

 is difficult to formulate. The sensitising dose of antigen 

 appears to produce some anti-body which reacts with, 

 or in the presence of, the second dose of antigen. The 

 necessity for an incubation period after the sensitising 

 dose points to this, as well as the fact that " passive " 

 anaphylaxis may be induced by injecting an animal 

 with the serum of a sensitised one ; the treated animal 

 suffers from anaphylactic shock on being injected with 

 the antigen. The substance which gives rise to the 

 anaphylactic shock is termed " apotoxin " by Richet and 

 " anaphylatoxin " by Friedberger, and it may be akin 

 to a precipitin. 



Discussion has taken place as to whether the reaction 

 is cellular and occurs in the cells, or humoral, occur- 

 ring in the body fluids. Experiments by Dale and 

 others show that reaction does take place in tissues free 

 from plasma. Dale 1 sensitised guinea-pigs, then excised 

 the' uterus, washed it free from blood and suspended 

 it in Ringer's solution. On flooding the uterus with the 

 homologous antigen contraction occurs. Specificity is 

 shown by the fact that only the homologous antigen 

 causes contraction, and an animal may be sensitised to 

 two or three different antigens, and the uterus contracts 

 when it is flooded in turn with the homologous antigens. 

 Once the reacting dose has been given and the uterus 

 has contracted, the muscle is no longer sensitive to the 

 antigen. But the substance produced by sensitising is 

 also present in the blood, as is shown by the fact that 

 passive anaphylaxis may be produced. Probably ana- 

 phylaxis is both cellular and humoral and can occur 



1 Journ. Pharmacol. and Exper. Therapeutics, iv, 1913-14, p. 167. 



