3904.] KRAEMER — NATURE OF COLOR IN PLANTS. 265 



Inasmuch as there seems to be a class of these principles which 

 are distinguished by their solubility, as well as reactions with 

 various chemicals, I venture to propose the name clwoynophyl for 

 these yellowish or orange-colored pigments. 



All of the coloring substances given in Table I are soluble in 

 xylol, ether and similar solvents, as well as alcohol, but are spar- 

 ingly soluble in water. 



There are several substances which behave much like the plastid 

 substances, but which are insoluble in xylol, ether, etc., and appear 

 to occupy an intermediate position between the true plastid color 

 substances and the cell-sap colors. I have therefore placed them in 

 class by themselves in Table II. 



Cell-sa? Color Substances. 



During the course of metabolism the plant cell manufactures 

 other color substances which are not combined with the protoplasm, 

 but which are contained in the cell-sap, or liquid of the cell. 

 These substances, unlike the plastid colors, are insoluble in xylol, 

 ether and similar solvents, but are soluble in water and alcohol, 

 which affords a means of separating them from the plastid colors. 

 These cell-sap pigments may occur in cells free from plastids or in 

 the vacuoles of cells containing plastids, but not associated with 

 them as a part of the organized body or plastid. They are usually 

 extracted along with the chlorophyl and remain in the hydro- 

 alcoholic solution after separation of the plastid pigment by means 

 of xylol or other solvent. These pigments have one property in 

 common with the chromophyl substances, namely, with alkalies, 

 potassium cyanide and sodium phosphate, they assume some shade 

 of green. They are distinguished, however, by the fact that the 

 colors are markedly affected by acids and alkalies and by iron salts. 

 They are in most cases also affected by other reagents, as shown in 

 the accompanying tables. These substances being so sensitive to 

 reagents, probably accounts for the various shades and tints 

 characteristic not only of flowers but of leaves as well. My obser- 

 vations on the germinating kernels of black Mexican corn show that 

 even in contiguous cells the constituents associated with the dye 



acid; potash alum, lo per cent.; ammonio-ferric alum, 5 per cent.; iodine solution 

 containing .1 per cent, iodine and 0.5 per cent, potassium iodide; tannin, 3 

 per cent. 



