Melvin Calvin (1911-1997), American biochemist who first described the photosynthetic process, now known as the Calvin Cycle. Calvin determined the process by tracking radioactive carbon dioxide through its transformation into carbohydrates. He allowed carbon-14 to be absorbed by plants, then mashed up the cells and separated the contents using paper chromatography. He discovered intermediate reaction products of photosynthesis and worked out the reaction scheme. He also discovered that photosynthesis proceeds in the absence of light. Calvin later confirmed which primary elements had formed the atmosphere from which primitive life developed. He received the Nobel Prize in Chemistry in 1961.
Melvin Calvin - Biography (The Nobel Foundation)
Calvin Photosynthesis Group Subject of History Project (Lawrence Berkeley National Laboratory)