266 KRAEMER — NATURE OF COLOR IN PLANTS. [Aprils, 



vary to such an extent that the pigment in one cell is colored red- 

 dish, in another bluish-green, and in another purplish. 



The results of the examination of the cell-sap colors are given in 

 Tables III, IV and V, and while it might seem a very easy matter 

 to divide plant colors into reds, blues and purples, it will be seen 

 that this is almost impracticable, and that the colors given in these 

 tables merge into one another. 



An examination of the color substances found in early spring 

 leaves and in autumn leaves showed that these substances are in the 

 nature of cell-sap colors, behaving toward reagents much like the 

 cell-sap colors of flowers, and indeed in some instances they are 

 apparently identical, as will be seen by comparing the results given 

 in Table VI with those given in Tables III, IV and V. 



Conclusions. 



1. The white appearance in flowers and other parts of plants is 

 due to the reflection and refraction of light in more or less color- 

 less cells separated usually by large intercellular spaces containing 

 air. 



2. The green color of plants is due to a distinct pigment, chloro- 

 phyl, contained in a chloroplastid, and appears to be more or less 

 constant in composition in all plants. The chloroplastid is 

 furthermore characterized by usually containing starch. 



3. The yellow color substance in roots, flowers and fruits is due 

 to a pigment, to which I have given the name chromophyl. This 

 substance is contained in a chromoplastid which varies consider- 

 ably in shape, and usually contains proteid substances in addition. 



4. In the inner protected leaf-buds there is a yellow principle 

 which I have termed etiophyl, and which is contained in an 

 organized body which I have termed an etioplast. The etioplast 

 does not appear to contain either starch or proteid substances. 



5. The blue, purple and red color substances in flowers are 

 dissolved in the cell-sap, and are distinguished for the most part 

 from the plastid colors by being insoluble in ether, xylol, benzol, 

 chloroform, carbon disulphide and similar solvents, but soluble in 



' water or alcohol. While quite sensitive to reagents yet none of 

 these colors behave precisely alike. 



6. Cell-sap color substances corresponding to the cell-sap colors 

 of flowers are also found in early or spring leaves and in autumn 

 leaves. 



