CAROTINOIDS IN THE PHANEROGAMS 69 



pointed out distinctly the difference between yellow flower pigments 

 dissolved in the cell sap and yellow ilower pigments deposited, appar- 

 ently always, in amorphous condition in the plastids. Courchet was 

 successful in recrystallizing the red, red-orange and yellow-orange 

 plastid pigments, but not the yellow plastid coloring matters. The 

 latter, however, gave the same color reactions with the lipochrome 

 reagents as the crystallizable pigments, and their great solubility in 

 absolute alcohol shows clearly that they are to be classified as xau- 

 thophylls. It is not so certain that the crystalline forms were carotin 

 in all cases on account of their somewhat variable solubility in alcohol. 



Following Courchet, carotin crystals were obtained by Immendorff 

 (1889) from extracts of the flowers of various members of the butter- 

 cup (Ranunculus) family and from various members of the hawkbit 

 (Leontedori) family, probably especially the so-called autumn dande- 

 lion (Leontedon autumnale). Mobius (1885) had already shown that 

 the peculiar oily appearance of the yellow buttercups, which is the 

 cause of their common name, is caused by the pigment being dissolved 

 in the cells in oil and not present, as usual, in plastid form. This 

 flower therefore appears to present an exception to the general rule 

 that flower carotinoids are present in chromoplastids. In this con- 

 nection, the idea of Hilger (1894) and his pupils Wirth (1891) and 

 Kirchner (1892), that the carotin pigment of the pot marigold flower 

 (Calendula officinalis) is a mixture of sterol esters of various fatty 

 acids and an unnamed colorless hydrocarbon, has been completely dis- 

 proved. Pabst (1892) proposed the same idea to explain the consti- 

 tution of the pigment of the red pepper (Capsicum annum) and Ehr- 

 ing (1896) the pigment of the tomato (Lycopersicum esculentum}. 

 Even if these authors had regarded carotin as a sterol-like substance 

 in union with fatty acids, which does not appear to have been the 

 case, the hydrocarbon character of carotin and the fact that xantho- 

 phylls apparently contain no hydroxyl group would render their con- 

 clusion untenable. 



We are dependent for our present knowledge of the distribution of 

 carotinoids among flowers upon the observations of Tammes (1900), 

 Kohl (1902), Schunck (1903), Tschirch (1904), Bidgood (1905) and 

 van Wisselingh (1915). Tammes, Kohl and van Wisselingh sub- 

 mitted the flowers examined by them to one or more of the micro- 

 chemical crystallization methods previously described, the last named 

 investigator supplementing these in certain instances with additional 

 tests on the crystals thus formed in order to determine, if possible, 



