Kraemer : Color in plants 81 



some writers. It may therefore be of interest to compare the 

 reactions of tannin with those already given. 



A solution of tannin, which is colorless, produces no color with 

 lime water, with acids, or with alum ; becomes deep-blue with 

 ferrous sulphate, which is rather characteristic, and reddish-brown 

 with alkalies. It is thus seen that tannin behaves very differently 

 toward these reagents except in the case of iron salts. 



An examination of the color-substances of a large number of 

 plants shows that the flower color-substances are distributed in all 

 parts of the plant. For example, the flower color-substance of 

 the rose occurs in the leaves and prickles as well as in the petals, 

 and this substance can be readily separated from the chlorophyl 

 associated with it in the leaves by treating an alcoholic extract of 

 the leaves with benzin. 



In an alcoholic extract which has been so treated, the benzin 

 layer at the top contains the separated chlorophyl and the alco- 

 holic layer at the bottom contains the flower color-substance, 

 which becomes more distinct by the addition of reagents. 



The color-substance in the root of the radish closely corre- 

 sponds to that in the flowers, and the color-substance in the grains 

 of black Mexican corn corresponds to that in corn silk. 



An extract of black Mexican corn shows reactions with chem- 

 icals closely resembling those obtained with various flower color- 

 substances, as of rose. 



The solution of black Mexican corn, which is of a reddish - 

 purple color, rapidly changing to purplish-red, becomes green with 

 lime water ; red with oxalic acid ; purple with alum, which is quite 

 pronounced ; and distinct blue with ferrous sulphate. 



The cell-sap color-substances are usually found in greatest 

 amount at the tips of the branches, this being well marked in the 

 foliage of the rose, and may be said to be rather characteristic of 

 spring foliage. Not infrequently in the purple beech the young 

 leaves will be of a distinct purplish-red color and almost entirely 

 free from chlorophyl, suggesting a correspondence in position and 



color to a flower. 



The results of my work further seem to show that there is a 

 fundamental cell-sap color-substance which occurs in two modifi- 

 cations in the plant, one becoming yellowish-red and the other pur- 



