18 CAROTINOIDS AND RELATED PIGMENTS 



in arils and roots, in algse lichens, fungi and bacteria; among ani- 

 mals they have been demonstrated in the egg yolk of the sea-spider, 

 in the retina of bird's eyes, in insects, such as Chrysomelidce and Coc- 

 cinellidcB, and in the secretions of various Crustacea-, such as various 

 kinds of Diaptoma, and Maia squinado as well as in still lower forms 

 of animal life. 



The lipoxanthins are thus seen to be a more or less indefinite group 

 of pigments, whose classification together under one head is secured 

 just as well by the older term lipochrome, which no doubt explains 

 why the proposed term never received wide recognition. 



Chromolipoids 



As our knowledge of the so-called lipochromes and lipoxanthins has 

 been extended by exhaustive researches regarding the various indi- 

 vidual representatives from both plant and animal sources the objec- 

 tions which have been raised by various workers to terms such as 

 lipochrome and lipoxanthin seem to be more and more valid. The 

 botanists have been the first to definitely break away from the old 

 terminology as exemplified by the citation from Kohl's monograph. 

 Czapek (1913a) proposes to meet the objections to the name lipo- 

 chrome by calling the pigments chromolipoids. His point of view is 

 that the lipochromes, at least in plants, are to be classed with the 

 lipoids by reason of their many fat-like properties, especially solu- 

 bility, and also because of their widespread occurrence in cells in 

 which lipoids are known to exist. Moreover, the lipochromes, in com- 

 mon with phosphatides and sterols, absorb oxygen very readily. 

 Czapek's terminology has much in its favor, in the opinion of the 

 author. It is at least preferable from many standpoints to the more 

 or less misleading term lipochrome. 



Carotinoids 



Attempts have not been wanting to secure uniformity in the termi- 

 nology of the yellow plant pigments. The first yellow plant pigment 

 to be isolated in crystalline form was carotin, the pigment of the root 

 of the cultivated carrot, Daucus carota. At one time the name caro- 

 tin was used to cover all the plant chromolipoids. When it became 

 known that differences existed between many of the so-called caro- 

 tins, the name was changed to carotinen, or investigators spoke of the 



