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



the solution filtered, the extract washed with hot water until the 

 filtrate is colorless ; the extract is then taken up with cold alcohol. 

 (2) In the other method the alcoholic solution is diluted with 

 water; and ether, benzin, benzol, xylol, or other similar solvent is 

 added, and the mixture shaken in a separatory funnel. The ethereal 

 layer containing the plastid color may be further purified by shak- 

 ing it in a separatory funnel with alcohol, adding sufficient water 

 to cause separation of the two layers. The ethereal solution is then 

 distilled and evaporated on a water bath to near dryness, and the 

 pigment taken up with cold alcohol. In either case the alcoholic 

 solution may be boiled for an hour or two with zinc in a reflux con- 

 denser, whereby the more or less oxidized plastid pigments are 

 restored. This is a particularly important procedure in the micro- 

 spectroscopic examination of chlorophyl, and may be used as a 

 means of detecting chlorophyl in other substances. 



In order to obtain the coloring principles in early leaves, as the 

 red coloring principle in the leaves of oak, rose, etc., it was found 

 most satisfactory to extract the material with alcohol, add xylol or 

 similar solvent, and then sufficient water to effect separation of the 

 solutions, using a separatory funnel. The cell-sap color remains 

 in the hydro-alcoholic solution, and the traces of xylol should be 

 removed by heating the solution on a water-bath, as the presence of 

 xylol causes a cloudiness in the solution on the addition of the re- 

 agents to be subsequently employed. 



The cell-sap colors of flowers, as of pansy, tulip, etc., are sepa- 

 rated from the plastid pigments in the same way as just mentioned 

 in connection with early leaves. 



The cell-sap colors in fall leaves are easily removed by treating 

 the more or less comminuted material with hot or cold water. 



In some cases there are several associated colors, and these may 

 be extracted separately by taking advantage of their varying solu- 

 bility, as in the case of carthamus, where the red principle is ex- 

 tracted with water and the yellow principle with alcohol. 



In still other cases special methods are employed, as in the ex- 

 traction of carotin from carrot according to the method proposed 

 by Husemann.* The grated carrot is mixed with water, squeezed 

 through cheese-cloth, and a small quantity of dilute sulphuric acid 

 and tannin added to the mixture, ibrming a coagulum which settles 

 to the bottom of the precipitating jar. The supernatant liquid is 

 removed by means of a syphon and the coagulum treated six or 



