By experimenting at the University of California, Melvin Calvin and his staff found the complete way for sugar synthesis. The following measures were used: carbon dioxide, a radioactive isotope of carbon, was labelled C14 and was supplied to the plants for this experiment.

The path C14 was then monitored and analysed, e.g. in dark and in light, under different conditions.

Once the experiment with the live plant was over, the plant was killed and the labelled compound was extracted from the dead plant for further analysis.

Based on the analysis in live and dead plants, Calvin and his co-workers finally discovered the pathway during light independent reactions.