268 LUTEINS. 



1. Lutein l . 



This pigment may be obtained from corpora lutea by extrac- 

 tion with chloroform. If the orange-coloured solution thus ob- 

 tained be allowed to evaporate spontaneously a fatty residue is left 

 in which the lutein is found in a crystalline form as minute either 

 rhombic prisms or plates, which are pleochromatic (see p. 217). They 

 are insoluble in water but readily soluble in alcohol, ether, chloroform 

 and benzol. These exhibit two absorption bands, one inclosing F, the 

 other about half way between F and G. 



If egg-yolk be extracted with a little alcohol and much ether, the 

 solution shows two bands similar to those already described for 

 lipochrin or frog's fat (p. 264), while sometimes a third faint band near 

 G may be seen, especially if the residue from the ethereal extract be 

 dissolved in carbon bisulphide and examined. If the residues from the 

 ethereal extracts of egg-yolk and corpora lutea be saponified and 

 extracted with carbon bisulphide, the solutions yield identical absorp- 

 tion spectra 2 . 



Maly 3 operating on the bright red eggs of a sea-spider (Maja 

 Squinado) considered that lutein (assuming its identity in this case 

 with that from ordinary egg-yolk) consists of two pigments, vitello- 

 lutein (yellow) and vitellorubin (red). For further details see the 

 original paper. Lutein is more or less rapidly bleached by the action 

 of light. 



2. Serum lutein. 



The serum from the blood of almost all animals is usually 

 of a more or less yellow colour; it is specially marked in the 

 case of the horse and ox, is also marked in the case of sheep 

 and man, and is but slightly present under normal conditions in 

 the serum of the dog, rabbit or cat. The colour has by different 

 observers been ascribed to different pigments. In some cases it may 

 be due, at least partly, to the presence of bile pigments or their 

 derivatives 4 , these being much increased in certain diseases such as 

 jaundice. But in addition to these it appears that the colour of all 

 pigmented serums is due to a specific pigment, which while it may 

 differ (?) slightly as obtained from the blood of different animals, 



1 See Capranica, loc. cit. on p. 265. 



2 Kiihne and Ayres, JL of Physiol. Vol. i. (1878), p. 127. Gives spectra. 



3 Monatshefte f. Chem. Bd. n. (1881), S. 18. Gives literature to date. See 

 recently Bein, Ber. d. d. chem. Gesell. Bd. xxm. (1890), S. 421. 



4 Hammarsten (Swedish). See Maly's Jahresb. 1878, S. 129 (Bilirubin in 

 blood-serum of horse but not of ox or man). Maly, Liebig's Annul. Bd. 163 (1872), 

 S. 77 (Hydrobilirubin). Mac Munn, Proc. Roy. Soc. Vol. xxxi. (1880), p. 231 

 (Choletelin). 



