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Dr. Thudichum on Luteine and the Spectra of [Jan. 28, 



always superposed in a curious manner. Possibly these crystals may be 

 rhombohedra imperfectly developed on four of their edges. They are 

 microscopic, yellow when thin, orange to red when thick, and have no 

 resemblance to any other known animal or vegetable substance. 



6. Reactions. — Luteine combines with few substances, mercury-acetate 

 being perhaps the only ordinary reagent by which it is immediately and 

 completely precipitated, as a yellow deposit. Mercury-nitrate produces a 

 yellow precipitate, which on standing becomes white. Nitric acid poured 

 over the crystals produces a blue colour, which immediately passes into 

 yellow. The blue is not produced when nitric acid is added to either 

 alcohol, chloroform, or ether solution, but appears with the solution in 

 acetic acid and disappears again rapidly. 



7. Affinity for Fats. — In the corpora lutea luteine is deposited in gra- 

 nules, which become the darker and larger the older the corpora grow. 

 In the yelks of eggs it also exists in granules ; and when extracted from 

 any of these bodies it is always mixed with a considerable amount of an 

 oily fat which contains cerebrine, and neutral fats, amongst them a peculiar 

 fat containing phosphorus, like cerebrine. In butter after clarification it 

 is found dissolved. 



8. Affinity for Albumen. — On the other hand, luteine has great attrac- 

 tion to albumen, and can only with difficulty be extracted from serum or 

 the fluid of ovarian cysts. 



9. Luteine in Vegetables. — In vegetable matters luteine is contained in 

 such a form that a clear watery solution cannot easily be obtained. All 

 vegetable matters, however, readily yield their luteine to alcohol, and form 

 by proper treatment clear solutions. In maize, luteine is accompanied by 

 fats which are somewhat similar to those of eggs. 



10. Type of new Spectra. — The spectrum of luteine is the type of the 

 spectra of a series of bodies which are probably chemically identical ; but 

 not all yellow vegetable, animal, or chemical products are identical with 

 luteine. 



11. New Spectra like that of Luteine. — The yellow-coloured matters 

 of the following plants present the spectrum of luteine, or one closely re- 

 sembling it: — (1) Crocus or saffron (stamina); (2) Helianthus annuus 

 (flower) ; the petals of the following plants — (3) Leontodon taraxa- 

 cum, (4) Leontodon (yarietas ?), (5) Gazania elegans, (6) Marigold 

 common, (7) Hypericum oblongifolium, (8) Acacia leprosa, (9) Galphi- 

 mia splendens, (10) Stigmatophyllum ciliatum, (11) Lankesteria elegans, 

 (12) Allamanda neriifolia, (13) Oolutea frutescens, (14) Tagetes lucida, 

 (15) Schkuhria atrovirens, (16) Diplotaxis tenuifolia, (17) Virgilia syl- 

 vatica, (18) (Enothera grandiflora, (19) Verbascum phlomoides, (20) 

 Tagetes pumila, (21) Helianthus macrophyllus, (22) Chrysopsis villosa, 

 (23) Helenium autumnale, (24) Obeliscaria pinnata, (25) Heliopsis 

 lavis, (26) Linosyris vulgaris, (27) Berberis Darwinii, (28) Solidago 

 serotina, (29) Ruta graveolens, (30) Mclilotus elegans, (31) Medicago 



