96 CAROTINOIDS AND RELATED PIGMENTS 



Lcathcsia marina Millardet., 1869; Molisch, 1905. 



Chorda filumTammes, 1900. 



Laminar ia saccharina Millardet, 1869; Reinke, 1876; Tummes, 1900; 



Molisch, 1905; Tswett, 1905, 1906; van Wisselingh, 1915. 

 Laminaria digitalis Tammes, 1900; Molisch, 1905; Kylin, 1912; Will- 



statter and Page, 1914; van Wisselingh, 1915. 

 Cutleria nwtti/Wa Millardet, 1869; Molisch, 1905. 

 Order Dictyotales. 



Dictyota dichotomy Millardet, 1869; Molisch, 1905. 



Dictyopteris polypodioidcs Tammes, 1900; Molisch, 1905; Kylin, 



1912. 



Halyseris polypodioides Millardet, 1869; Molisch, 1905. 

 Padina Pavonia Molisch, 1905. 



Molisch's (1905) contributions to the carotinoids of brown algae 

 were, (1) in showing that the water-soluble phycophain exists only 

 in the dried plants or those which have been placed in hot water for 

 a few minutes, (2) in rediscovering the blue color reaction with HC1. 

 Molisch obtained the latter reaction either by extracting the fresh 

 plants with alcoholic-HCl (98 volumes of alcohol and 2 volumes of 

 con. HC1) or by adding HC1 to the alcoholic layer after the Kraus 

 separation, using petroleum ether for extracting the carotin and 

 chlorophyll. Molisch, however, did not attribute this reaction to a 

 carotinoid, but to a colorless "Icucocyan" in the plant, which gave rise 

 to a blue "phaeocyan" with HC1. 



Tswett (1905) was quick to point out Molisch's error with respect 

 to the so-called leucocyan reaction, showing that this was due to the 

 special carotinoid, fucoxanthin, in the plants, as Sorby (1873) had 

 pointed out many years earlier. Tswett (1906) was thus led to make 

 a closer study of the Phaeophyceae pigments, using Fucus and Lami- 

 naria for his material. He showed first that phycophain is a post- 

 mortem oxidation product and does not exist in the living plants. He 

 next made a careful examination of the chromatophor pigments of the 

 living plants making use of the relative solubility and chromatographic 

 adsorption properties of the carotinoids. By this means he showed 

 definitely that at least three carotinoids are present, namely, fuco- 

 xanthin, carotin, and xanthoph'yll. The former is the principal pig- 

 ment. It corresponds to the xanthophylls of the higher plants in being 

 adsorbed from pure petroleum ether and carbon clisulfide by calcium 

 carbonate and other finely divided materials, and by remaining hypo- 

 phasic in the Kraus separation between petroleum ether and 80 per 

 cent alcohol. It differs from the xanthophylls of the higher plants in 

 the position of its absorption bands in the spectrum, by the reddish- 

 brown color of its concentrated solutions, by the fact that it is attacked 



