162 CAROTINOIDS AND RELATED PIGMENTS 



the blue-green part of the spectrum. Merejowsky (1881, 1883) de- 

 scribed the same pigment under the name zoonerythrine, and enu- 

 merated various species of Crustacea in which it occurred. Maly 

 (1881), working with the red eggs of the spider crab, Mala Squinado, 

 differentiated between a red vitcllorubin and a yellow vitellolutein, 

 showing many solubility and chromatic properties in common, but 

 differing in their spectroscopic properties and in their affinity for 

 alkalis. Krukenberg (1882k) included both pigments under his lipo- 

 chromes, but was convinced of the identity of the red pigment with 

 Kiihne's rhodophane. Halliburton (1885) made a special study of 

 the red "tetronerythrine" in the blood of the lobster, crab and cray- 

 fish, but noticed a difference between the fresh water (Astacus fluvi- 

 atilis) and salt water (Nephrops norwegicus) form of the latter, in 

 that the pigment was almost absent from the salt water animals. 

 Yellow chromolipoid is not mentioned. MacMunn (1883) examined 

 the liver and bile of lobsters, crabs and crayfish for lipochromes, find- 

 ing yellow "lutein" in some cases and red "tetronerythrine" in others. 

 Many of the investigators mentioned also made a cursory examination 

 of the pigments in the hypoderm, but these have been studied espe- 

 cially by MacMunn (1890) and Ncwbigin (1897) for the larger 

 species of Crustacea and by Blanchard (1890) and Zopf (1893a) for 

 the smaller. The latter investigators used chiefly the little red Diap- 

 tomus bacillifcr, found in fresh water, for the source of their material. 

 Blanchard found only one pigment, but Zopf describes both red and 

 yellow pigments, the red one being called diaptomin. 



This brief historical survey makes it clear that two distinct types 

 of chromolipoids are present in Crustacea, one characterized by its red 

 color and the other by a more yellow hue. How are these pigments 

 related to the carotinoids? 



With regard to the red pigment its properties have been described 

 most fully by Maly (1881), Zopf (1893a) and Newbigin (1897) as 

 follows: The ether and petroleum ether solutions are yellow, when 

 dilute, but the alcohol, benzene, chloroform and carbon disulfide solu- 

 tions are always red or pink, even on great dilution. Water, also, 

 acting on material such as the dried Maia eggs forms a protein solu- 

 tion in which the coloring matter is apparently dissolved, and from 

 which the pigment can be removed by coagulating the protein with 

 heat or alcohol and extracting the dried precipitate. The pigment is 

 very unstable when pure and fades very rapidly in contact with air, 

 even in darkness. This bleaching is undoubtedly an oxidation, and 



