- 2k' 



of the pigments, the chromatograms typical of different kinds of plants 

 are portrayed by simplified drawings. If the extraction and separately 

 procedures are followed, there is little difficulty in reproducing these 

 chromatographic observations. It should be kept in mind, however, that 

 these results were obtained only after many empirical trials. Devia- 

 tions from the procedures, only a few of which can be indicated here, 

 may lead to incomplete separation and to alteration and contamination 

 of the natural pigments, 



I The identification of the pigments was based upon spectral absorp- 

 tion curves, color reactions Tirith acids and readsorption with authentic 

 preparations. Spectral absorption curves of the new pigments are re- 

 produced as the so-called characteristic spectral adsorption curves, 

 the shape of which is independent of the concentration of the pig- 

 mentsl»^05l*l^. 



For summarization of the observations and as an aid to readability, 

 the plant species that wore studied have been tabulated according to 

 their principal toxonomic classes. The tables of these species have 

 been arranged in the form of appendices with cross references to the 

 respective figures showing the chromatograms of the pigments in columns 

 of powdered sugar. The locations of the species, their natural habi- 

 tats, and minor variations of the pigment systems are recorded in the 

 tables, 



PLANT MATERIAL AND ANALYTICAL METHODS 



Selection of Plant Material 



In the selection of plant material an attempt was made to examine 

 species of special interest because of their taxonomic position », 



