f 



m 





Courtesy of L. Zechmei«te/. 

 Fig. 9-1. Carotene. 



"^ 



Fig. 9-2. Vitamin A (with one molecule of solvent of crystallization). 

 Yellow crystals first isolated by Prof. Harry N. Holmes and Dr. Ruth E. 

 Corbet, Oberlin College, 1936. 



206 



