PROTEIN SENSITIZATION OR ANAPHYLAXIS 291 



does it cause animals treated with it to elaborate an anti- 

 toxin. 



That the anaphylactic poison is a protein derivative is 

 certain; whether it is still' a biuret body has not been deter- 

 mined. The chemistry of the protein poison has been 

 discussed (p. 101). 



(3-iminazolylethylamin. This amin is produced by split- 

 ting off carbon dioxide from histidin, and this may be done 

 by either chemical or bacterial agencies. It was first 

 prepared synthetically by Windam and Vogt, 1 and then 

 by Ackermann 2 by the action of putrefactive bacteria on 

 histidin. About the same time it was detected in ergot, 

 and its physiological action investigated by Barger and 

 Dale. 3 In the same year Kutscher 4 isolated from ergot a 

 substance which chemically could not be distinguished 

 from this amin, but which was believed to have a some- 

 what different physiological action. /3-iminazolylethylamin, 

 hereafter designated by the abbreviation 0-i, was suggested 

 as a possible agent in inducing anaphylactic shock by Dale 

 and Laidlaw, 5 who made a thorough study of its physio- 

 logical action. It is highly poisonous, 0.5 mg. being sufficient 

 to kill a guinea-pig, with all the symptoms of anaphylactic 

 shock, when administered intravenously. Dale and Laidlaw 

 describe its action on guinea-pigs as follows: "In large 

 guinea-pigs, weighing 800 to 1000 grams, injection of 0.5 

 mg. into the external saphenous vein caused death in a few 

 minutes. The immediate effect was a marked respiratory 

 impediment, resulting in violent but largely ineffective 

 inspiratory efforts, during which the lower ribs were drawn 

 in. After a time the respiratory convulsions ceased, and 

 the animal lay comatose, though the heart continued to 

 beat for some time longer. Post mortem: The lungs were 

 found permanently distended. If the fatal amount were 



1 Berichte, 1907, xl, 3691. 



2 Zeitsch. f. physiol. Chem., 1910, xlv, 504. 



3 Proc. Chem. Soc., 1910, xxvi, 128. 



4 Zentralbl. f. Physiol., 1910, xxiv, 163. 



5 Journal of Physiology, 1911, Ixi, 318. 



