82 Kraemer : Color in plants 



plish-red with acids. These two modifications may occur in the 

 same part of the plant, as in the petals of the poppy, or in widely 

 separated parts, as in radish,. where the substance which becomes 

 yellowish-red with acids occurs in the root, and the one which 

 becomes purplish-red occurs in the flower. 



Inasmuch as these two modifications behave in addition differ- 

 ently toward other reagents they might be said to show an analogy 

 to some of the sugars, as well as other substances, of which two 

 modifications occur. 



The existence of two modifications of the fundamental cell-sap 

 color-substance is well exemplified in the case of roses, some fifty 

 sorts having been examined. The color-substances extracted from 

 deep-red or crimson roses give a yellowish-red color with mineral 

 acids, a deep-blue or purple with potash-alum, ferric chloride or 

 ammonio-ferric alum. The solutions obtained from pale-red or 

 pink roses give a purplish-red with mineral acids, a pale-purple or 

 pale purplish-brown with potash alum, and olive-green with ferric 

 chloride or ammonio-ferric alum. With some of the hybrid tea 

 roses and some of the yellow roses intermediate tints are obtained 

 by the use of these reagents corresponding to the colors in the 

 parent plants. 



Color in autumn leaves 



The coloring matters in both spring and autumn leaves closely 

 resemble the cell-sap color-substances of flowers, although it is the 

 spring leaves which give the most satisfactory results. The fact 

 that in the autumn leaves there is little or none of the plastid pig- 

 ment present would point to the conclusion that the color-sub- 

 stances occurring in these leaves are in the nature of by-products 

 and of no further use to the plant. Of course in the case of 

 autumn leaves we know that these products cannot be further 

 utilized, and for this reason we are justified in regarding them as 

 waste products. 



Color in marine algae 



The marine algae offer interesting material for the study of vege- 

 table color-substances, and probably will be found to throw some 

 light on the subject of the origin of color in plants. The plastids 

 are numerous, constituting a large proportion of the components 

 of the cell. They are variously colored, being red in the red algae, 



