ANAPHYLAXIS 371 



safely predict that no such exceptions will be found. It is the large 

 class of proteins, therefore, whatever their source, which may act as 

 the a anaphylactic antigens." However, in this connection as well 

 as in the larger problem of the nature of antigens in general, it has 

 been difficult to decide whether or not the antigenic property is en- 

 tirely confined to proteins or whether other substances, such as the 

 lipoids, must be included in the definition. The problem has been 

 the same here as in other serum phenomena, but much special experi- 

 mentation has been done iipon the question with particular refer- 

 ence to anaphylaxis and the possibility of sensitizing animals with 

 lipoids. 



As in the case of similar investigations in regard to antibody 

 formation, the results obtained in this work have been somewhat 

 confusing. Pick and Yamanouchi 34 extracted beef and horse sera 

 with alcohol, and evaporated and redissolved the solutions until they 

 neither contained coagulable protein nor gave the Biuret reaction. 

 With this material they obtained a few positive anaphylactic experi- 

 ments. Similarly curious are the results of Bogomolez, 35 who suc- 

 ceeded in sensitizing and producing shock with the lipoids extracted 

 from egg yolks. Although such experiments would tend to persuade 

 us that lipoidal substances may actually have sensitizing (therefore 

 antigenic) functions, this does not follow necessarily. As Pick and 

 Yamanouchi themselves point out, it is practically impossible to 

 demonstrate with certainty the presence of slight traces of proteins 

 as impurities in lipoid preparations, and we know especially from 

 Rosenau and Anderson's work how minute are the quantities of 

 antigen which still serve to sensitize. It is possible, moreover (a 

 thought developed particularly by Pick and Schwartz 36 and by 

 Landsteiner 37 ), that we are dealing in many cases with combina- 

 tions of protein and lipoid a form of chemical substances of which 

 very little is known analytically, but the existence of which many 

 biological facts lead us to assume. 



That the anaphylactic reaction is specific we have mentioned in 

 the brief summary we have given of Rosenau and Anderson's work. 

 These authors use the adjective "quantitative," by which they sim- 

 ply mean to convey that the specificity here is not absolute, any more 

 than it is absolute in the case of any of the known serum reactions. 

 An animal sensitized with a certain variety of protein, animal serum, 

 etc., reacts with disproportionately greater delicacy to a second injec- 

 tion of the same variety than of any other substance. In fact, apart 

 from a few cases mentioned by Gay and Southard, there are not many 

 instances of marked non-specific anaphylactic reactions. Still we 



34 Pick and Yamanouchi. Zeitschr. f. Immunitatsforschung, Vol. 1, 1909. 



35 Bogomolez. Zeitschr. f. Immunitatsforschung, Vols. 5 and 6, 1910. 

 56 Pick and Schwartz. Biochem. Zeitsch., 15, 1909. 



37 Landsteiner. Ref. "Weichhardt's Jahresbericht," 6, 1910. 



