CAROTIN, THE PRINCIPAL YELLOW PIGMENT OF MILK FAT. 32^ 



Hansen l first showed the presence of lipochromes in algae and 

 Tammes 2 has lately shown their presence in a large number of these 

 plants. Zopf 3 has investigated the lipochromes of fungi and especi- 

 ally of bacteria, the first lipochrome-producing bacteria being pointed 

 out by him. 



The Lipoehrome or Lutein of Egg Yolk. It will be readily agreed 

 that while some order has been attained in classifying the widely dis- 

 tributed animal pigments, by means of the convenient and flexible 

 classification "lipochromes," our knowledge of the animal pigments is 

 far from being satisfactory when compared with the status of the 

 orange and yellow plant pigments, the carotins and xanthophylls. The 

 science of animal chromotology should accordingly be exceedingly 

 grateful for the recent work of Willstatter 4 and Escher, on the lutein 

 of egg yolk, the result of which has been to throw new light upon 

 the constitution of the lipochromes of the higher animals and upon 

 their relations to the carotins and the xanthophylls. 



The main pigment of the yolk of hen's eggs was isolated in 

 crystalline form by these investigators, and when in approximately 

 pure condition showed sufficiently close agreement with the constitution 

 of xanthophyll that the authors claim that the egg lutein on account 

 of its melting point (195-196 C. corrected) is a true isomer of the 

 crystalline xanthophyll of green plants. In all its other properties in- 

 cluding its spectroscopic absorption bands, the egg lutein was identical 

 with the crystalline plant xanthophyll. 



It is worthy of note also that during the isolation of lutein a 

 minor constituent was noticed which gave every indication of being 

 closely related to carotin; but as it was present in very small amount 

 compared with the xanthophyll it was disregarded. 



In concluding the review of this investigation it will be important 

 to mention that the authors state that one of them, i. e., Escher, is at 

 present investigating the pigment of the corpus luteum which they state 

 has been found to belong to the hydrocarbon or carotin group of 

 pigments. 5 



1. Arbeit Botan. Inst Wurzberg 3, 296 (1883). 



2. Loc. cit. 



3. Ber. Botan. Gessel. 9, 27 (1891). 



4. Zeit Physiol. Chem. 76, pp. 214-225 (1912). 



5. Note Since writing the above, Dr. Escher has published his investiga- 

 tions which show that the corpus luteum pigment is in every respect identical 

 with the carotin of the carrot and of green plants. Zeit. f. Physiol. Chem. 83, 

 p. 198 (1913). 



