First Crystals of Insulin 

 prepared by 

 Dr. John J. Abel 



1% 





s-j 



> -tt^' 



Figure 2. Dr. Abel was the first to obtain insulin in chemically pure crystal- 

 line form. He isolated the hormone when he was sixty-nine years old. For 

 months after he first did it, he was unable to repeat the performance, and many 

 chemists were skeptical of his achievement. Ultimately he found the answer and 

 crystalline insulin is now commercially prepared. 



Figure 3. How Abel's first insulin crystals (still kept at Johns Hopkins) 



appeared under the microscope. 



