CHLOROPHYLL (Gk. xXi.ophc , light green, and OudiXer, leaf). The green coloring matter possessed by almost all plants that are not of a parasitic or saprophytic habit. It is soluble in ether, alcohol, chloroform, carbon disulfid, olive oil, benzine and other organic solvents, and when dissolved exhibits a red fluorescence and a very characteristic absorption spectrum. Willstatter has pointed out that there are four' pigments in green leaves all of which used to go under the name of chlorophyll. These are chlorophyll a, blue-black in the solid state and green-blue in solution, of the formula C.1-1.05N4Mg; chlorophyll b, CuI-1“0.14.Mg, green-black in the solid state and pure green in solution ; the orange-red carotin, C.Iim; and the yellow xanthophyll, WINO,. All of these he has isolated in a pure state. There is good evi dence that these sub-lances are not mere arte facts (if the isolation-process, but exist as such in the living cell. In the first place, the trans mission spectra of these substances exhibit the lines shown by that of the living leaf. In the second place, that curious phenomenon of the chlorophyll in the leaf, that it cannot be ex tracted by solvents free from water, has also been exhibited by Willstatter in colloidal solu tions of the extracted chlorophyll, and is conse quently no evidence of the hydrolysis of chloro phyll during its extraction.
The chlorophyll obtained from different plants has been shown to be always made up of the same constituents in much the same pro portions. Other pigments besides the chloro phyll-constituents, however, are to be found in the cells of many plants, in very close associa tion •with the chlorophyll-constituents proper.
These ate especially to be found in the brown, the red and the blue-green alga.
The function of chlorophyll in the plant is to take part in the photosynthesis of carbohy drates from carbon dioxide and water, but no experiment as yet undertaken has exhibited this action on the part of chlorophyll in vitro. The action of chlorophyll is bound up with the entire structure of the chloroplasts (q.v.), or chloro phyll bearing bodies in the cells of the plant. It ha•been found that the photosynthetic activity of plants is not simply proportional to their chlorophyll-eontent, and for this and other rea sons Willstatter has been led to postulate an enzyme in the plant cell, which acts together with chlorophyll in the production of carbohy drates, so' that the rate of carbohydrate genera tion is a funbtion of two independent variables, if not of more.
The syStematization of the chemistry of chlorophyll is due to Willstritter, although in many important points his work was anticipated by the British physicist G. G. Stokes in the six ties of, the last century. Both Stokes and Will statter made use of the method of separating two substances that depends on their unequal solubilities in different solvents. With the pure materials that he has obtained in this way, Will statter has made a number of highly interesting experiments. For example, he has produced a number of substances in which the magnesium of chlorophyll is replaced by other metals. Con sult Jorgensen, I., and Stiles, W., As similation) (in New Phytologist, 1915).