PHENOMENA FOLLOWING IMMUNIZATION 97 



antitoxins. Rabe 70 has recently questioned the results of Abel and 

 Ford with Amanita phalloides. He believes that the poison with 

 which Ford worked is not a glucosid, but is of protein nature. In 

 the case of Rhus, however, Ford's conclusions have not, to our knowl- 

 edge, been challenged. 



With these and a few other less important exceptions, however, 

 observers have uniformly concluded that antigenic property and 

 protein structure are inseparably associated. All procedures by 

 which proteins have been hydrolized into their simpler fractions, 

 chemical splitting, tryptic or peptic digestion have in every case 

 resulted in a simultaneous loss of protein reaction and antigenic 

 property. 



Many attempts have also been made to show a relation between 

 antigenic properties and the lipoid constituents of cells. These en- 

 deavors were obviously stimulated by the observation that many 

 lipoids are capable of binding antibodies in vitro, and that, in ner- 

 vous tissues, toxin fixation was in some way related to the richness 

 in lipoids of these structures. Bang and Forsmann 71 accordingly 

 treated animals with ether extracts of red blood cells claiming that 

 this resulted in the production of hemolysins. And these results 

 have been confirmed by Landsteiner and Dautwitz. 72 The latter, 

 however, suggest that the hemolysin production may have been in- 

 duced, not by the lipoidal substances in solution, but by other anti- 

 genic substances which had gone into colloidal suspension in the 

 ether extracts. Much similar research on the antigenic nature of 

 lipoids has been done, but, after reviewing this very thoroughly, 

 Landsteiner comes to the conclusion that no definite proof of the 

 antigenic nature of any pure lipoid has so far been presented. The 

 problem is experimentally complicated by the fact that, as Land- 

 steiner 73 suggests, the antigen may often be present as a lipoid- 

 protein combination, and as such go into solution or fine emulsion in 

 the organic solvents ; also the lipoids possess the curious property of 

 altering the solubilities of proteins and other substances by their 

 presence. 



Summarizing our present knowledge of the chemical nature of 

 antigens, then, we must conclude that, with the exception of Ford's 

 glucosids, no protein-free antigens have been thus far demonstrated. 



In the light of this fact it is all the more remarkable that antigen- 

 antibody reactions are specific. For we possess no chemical methods 

 by which one variety of protein can be distinguished from another. 

 And yet the serum antibodies produced with each species of bacteria 



70 Rabe. Zeitschr. f. exp. Path. u. Therap., Vol. 9, 1911. 



71 Bang and Forsmann. Hofm. Beitr., 1906 ; Centralbl. f. -Bakt., 40, 1906. 



72 Landsteiner and Dautwitz. Hofm. Beitr., 9, 1907. 



73 Landsteiner. "Wirken Lipoide als Antigene ?" Weichardt's Jahresbe- 

 richt, Vol. 6, 1910. 



