Chemical Basis of Genus and Species 63 



interpretation was not generally accepted and received 

 a different interpretation by Bayliss and other workers. 

 Gay and Robertson were able to show that paranuclein 

 when injected into an animal will sensitize guinea-pigs 

 for anaphylactic intoxication for either paranuclein 

 or casein and apparently indiscriminately. The pro- 

 ducts of complete peptic digestion of casein had no 

 such effect, but the synthetic product of this diges- 

 tion obtained by Robertson's method has the same 

 specific antigenic properties as paranuclein, thus 

 making it appear that Robertson had indeed suc- 

 ceeded in causing a synthesis of paranuclein with the 

 aid of pepsin from the products of digestion of casein 

 by pepsin. 



There are a few statements in the literature to the 

 effect that the specificity of organisms might be due 

 to other substances than proteins. Thus Bang and 

 Forssmann claimed that the substances (antigens) 

 responsible for the production of hemolysis were of a 

 lipoid nature, but their statements have not been con- 

 firmed, and Fitzgerald and Leathes' reached the con- 

 clusion that lipoids are non-antigenic. Ford claims 

 to have obtained proof that a glucoside contained in 

 the poisonous mushroom Amanita phalloides can act 

 as an antigen. But aside from this one fact we know 

 that proteins and only proteins can act as antigens and 



* Fitzgerald, J. G., and Leathes, J. B., Univ. Cat. Pub., 1912, "Patho- 

 logy," ii., 39. 



