PROTEIN SENSITIZATION OR ANAPHYLAXIS 335 



solution of colloidal silicic acid, it retains its toxicity for 

 several hours. The source of the poison in coagulation 

 blood has been discussed and variously explained. Kohler 

 thought the fibrin ferment is the poison, but this was shown 

 not to be true by Boggs. Studzinski suggested that the 

 poison might come from the mechanical disruption of the 

 red corpuscles, but Moldovan and Doerr have shown that 

 the plasma or serum may be absolutely free from both 

 hemoglobin or cells and still be poisonous. Freund thought 

 that the poison might come from the disrupted blood plate- 

 lets, but in rapid centrifuges even the platelets may be re- 

 moved and even then the plasma or serum may be poisonous. 

 However, the role that the platelets play in coagulation still 

 suggests that they may furnish the matrix for the poison. 



The toxicity of extracts of normal tissue, especially of 

 the lungs and lymph nodes, is most interesting in this 

 connection. If the normal lungs of a rabbit or guinea-pig 

 be digested for two hours in physiological salt solution, the 

 solution kills promptly on intravenous injection. Homolo- 

 gous organ extracts are more active than heterologous. 

 Rabbits are the most susceptible animals used so far. The 

 poison seems to be destroyed when heated to 70; it does not 

 pass through a Berkefeld filter, and is absorbed by kaolin 

 as is anaphylatoxin. The addition of serum either homolo- 

 gous or heterologous seems to destroy or neutralize the 

 poison after contact of one hour or more. Doerr states that 

 the fresh vaccine growth just scraped from a calf with a 

 curette furnishes an extract which kills rabbits instantly 

 on intravenous injection. These extracts seem to owe their 

 effects to a coagulating ferment. 



Section of a dying animal shows the left heart, and the 

 pulmonary arteries and veins filled with coagula. Doerr 

 admits that poisoning with organ extracts from normal 

 animals is quite unlike death from anaphylactic shock. 

 In the former the blood is coagulated; in the latter it is 

 fluid. But Doerr holds that the formation of thrombi during 

 life is not the sole cause of death after the administration 

 of extracts from normal tissues or after the intravenous 



