CONCERNING THE PIGMENTS OF THE TWO-SPOTTED OCTOPUS AND THE OPALESCENT SQUID

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Abstract
The kinds and tissue-distribution of various pigments in the cephalopods Paroctopus bimaculatus and Loligo opalescens are described and discussed. Melanins, stored in quantity in eyes and ink of both species, are far more plentiful in the integument of the octopus than in that of the squid. Flavines were detected with certainty only in the pericardial (excretory) glands of the octopus. This species also yielded, from its kidneys, a water-soluble, iron-containing red pigment with reducing properties. Carotenoids were present only in traces in any of the organs of the squid. This was likewise true of the octopus, save in the liver-pancreas of this species, which contained a variety of carotenoids in amounts of 3.5 mg. (lutein equivalents) per 100 grams of moist tissue (average value). Ink from the sac adjacent to the liver contained 0.55 to 0.70 mg. lutein equivalents per 100 grams. In the liver of Paroctopus, free and esterified xanthophylls, predominantly of the lutein class, were accompanied by smaller amounts of other xanthophylls, β-carotene and an additional unfamiliar carotene, and a unique carotenoid acid, appearing on hydrolysis, not identical spectroscopically with astacene or with the metridene of Fox and Pantin. The ink of this species yielded no carotenes, but free and esterified xanthophylls and (on hydrolysis) a carotenoid acid similar to respective compounds recovered from the liver. Whilst starvation brought about the gradual disappearance of carotenoids from liver and ink, autolysis of the liver or incubation of its ground tissues resulted in only slow loss of the pigments.

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