Born in Decatur, Illinois, in 1906, Folkers graduated from the University of Illinois in 1928 and received his Ph.D. in organic chemistry from the University of Wisconsin in 1931. After postdoctoral work at Yale University, Folkers joined the Laboratory of Pure Research at Merck Laboratories where, over the next 30 or so years, he gradually rose in rank until he became director of the firm's fundamental research program.

Working for a pharmaceutical company, Folkers naturally devoted the lion's share of his attention to research on potentially useful therapeutic agents, such as vitamins and antibiotics. Through the 1930s Folkers and other Merck researchers helped establish the chemical structure of several members of the vitamin B family, including pyridoxine, biotin, and pantothenic acid. In 1938, however, Folkers began to concentrate on an antipernicious anemia factor, located in liver tissue by two physicians, George Richards Minot (1885-1950) and William Parry Murphy, a decade earlier.

Until...