Chapter 



10 



Some Unsolved Problems in 

 Immunology 



By MICHAEL HEIDELBERGER 



It is always a grateful task to discuss the un- 

 answered riddles of a science. Not only are these far more 

 numerous than the puzzles that have been solved, but the 

 relatively retarded knowledge of the unsolved mysteries 

 permits one to cast aside the customary restraints of cau- 

 tion, give rein to one's imagination, and fondly suppose 

 that the resulting beams of light will illumine wide corners 

 rather than lose themselves in the murk. Let us, therefore, 

 hopefully select a few outstanding problems in immu- 

 nology. 



Where and how are antibodies formed? There are clues 

 and there are theories, but the latter lack experimental 

 basis. 



What are the relationships between chemical constitu- 

 tion and immunological specificity? The pioneering studies 

 of Landsteiner covered the broad range of organic chem- 

 istry and posed the problem of the natural antigens in a 

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