In 1947, Gerty Theresa Cori, nee Radnitz, was awarded a share of the Nobel Prize in Physiology or Medicine for the discovery of the course of the catalytic conversion of glycogen. Gerty and Carl Cori investigate how glycogen is broken down into glucose and, in 1938-1939, were able to both identify the enzyme that initiates the decomposition and also to use the process to create glycogen in a test tube.