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THE CHEMISTRY OF ANTIGENS 



carbohydrates, particularly those found in micro-organisms, are of immunological 

 significance, and perhaps they may exist in the living cells in combinations that make 

 them of antigenic importance. The protein-lipoid combination is frequently reported 

 to be a better antigen than the protein alone; the carbohydrates from many bacteria 

 seem type specific, whereas the proteins from which they are separated are only 

 species specific. The idea that the specificity of an antigen may be determined by a 

 relatively small atomic group in the large antigen molecule becomes much more than 

 conjecture when substantiated by the careful experiments of Landsteiner and his 

 colleagues. The fact that amounts of protein too small to be detected in the concen- 

 trations used by any of the methods in general use have been known to be definitely 

 associated with antibody production should be considered in the interpretation of 

 any experiments done with apparently protein-free materials. 



