236 WARFIELD T. LONGCOPE AND GEORGE M. MACKENZIE 



the skin reactions brought about by the amins has been made by Sollmann 

 and by Sollmann and Pilcher, who have shown that though numerous chem- 

 icals may produce urticarial reactions in the skin, there are two, namely, 

 phenylethylamin and histamin, which produce the most definite and pro- 

 nounced response. These observations upon the skin reactions of histamin 

 have now been repeatedly confirmed and are well known. There is one 

 report by Sieburg in which histamin was injected subcutaneously into a 

 woman and was followed almost immediately by generalized urticarial 

 eruptions. 



It may thus be seen that very few observations are on record which 

 serve to throw any light upon these so-called protein reactions in the 

 human being and though it is obvious that the introduction, particularly 

 into the circulation, of foreign proteins of many sorts will call forth a 

 very marked and rapid reaction on the part of the body, yet the toxic sub- 

 stance which is responsible for this is unknown, and the question of its 

 origin from the foreign material injected or from the proteins of the in- 

 dividual is as yet unanswered. 



