In the 1960s, two Australian scientists, M.D. Hatch and C.R. Slack described a new pathway for carbon fixation in photosynthesis. The Hatch-Slack pathway describes a biochemical system in which carbon is first incorporated into the four-carbon molecule, oxaloacetic acid. Earlier, in the 1950s, an American scientist, Melvin Calvin, uncovered a chemical pathway for photosynthetic carbon fixation that came to be called the Calvin Cycle. In his scheme, carbon was first fixed into the three carbon compound, 3-phosphoglyceric acid (PGA). He was awarded the Nobel Prize in for this discovery in 1961. For a time the Calvin Cycle was thought to be the only carbon fixation pathway. Hatch and Slack's surprising discovery proved otherwise. Their efforts were aided by the work of G.O. Burr and his colleagues at the Sugar Cane Research Institute in Hawaii who reported that PGA was not the first...