Chlorophyll, the green coloring material of plants, is not to be found in the animal kingdom. Its chief function, the transformation of light energy into chemical energy, is performed by means of the process known as photosynthesis, the manufacture of carbohydrates from water and carbon dioxide in the presence of light.
The name chlorophyll was given to the green coloring matter of plants by the French chemists Pelletier and Caventou in 1817. Berzelius in 1839 made unsuccessful attempts to determine its chemical structure. Stokes, the British physicist, in 1864 showed that it was a mixture of several chemical substances. Nine years later Sorby separated it into four pigments, two yellow and two green, by partition between immiscible solvents. The work was ignored until Willstätter, who is responsible for most of the knowledge of the chemistry of chlorophyll, repeated and extended the investigation. Between 1906 and 1914 he and his collaborators