BIOLOGICAL RELATIONS BETWEEN CAROTINOIDS 183 



view that the animal lipochromes are of animal origin coincides with 

 Krukenberg's (1886) conclusion in the summary of his extensive 

 c-hromolipoid studies, where it is stated that, "they (i.e., the lipo- 

 chromes) originate in most cases from fat-like substances." A more 

 specific instance of the same general conclusion reached by one of the 

 foremost earlier workers on animal lipochromes is found in the paper 

 by Zopf (1893a) describing the yellow carotin-like pigment in the 

 little fresh-water crustacean, Diaptomus bacillifer. Zopf states, "I 

 could mention an objection which could be raised against the two- 

 banded yellow carotin found in these Crustacea. One could say that 

 it is not produced by the organs of the crab but perhaps comes from 

 the chlorophyll-containing algae which serve as their food, and which 

 contain a two-banded yellow carotin. However, this can not be true 

 because the animals with which I worked were preserved in alcohol 

 and no trace of chlorophyll was extracted which would have been the 

 case had algae been present in their digestive tract."- "The antennae 

 of Diaptomus Castor J urine is colored exclusively by diaptomin while 

 the body cavity contains fat masses of purest yellow. I believe that 

 the yellow carotin is produced by these animals just like the diap- 

 tomin." It is clear from these citations that Zopf saw no evidence 

 of a biological relationship between plant and animal carotinoids. 

 On the other hand Poulton (1885) believed that yellow pigment in 

 caterpillars was derived from the "xanthophyll" (carotinoids) of the 

 food and the green color from chlorophyll. Poulton later (1893) sub- 

 mitted his experimental proof of the derivation of chlorophyll by the 

 caterpillar from its food, an experiment which is classic so far as the 

 demonstration of derived pigments in animal colorations is concerned. 

 Goode (1890) made a particularly interesting observation, which can 

 hardly be classed as an experiment, but which verifies the probability 

 of a biological relationship between plant and animal pigments in 

 another species. To quote directly from his paper: "On certain ledges 

 along the New England coast the rocks are covered with dense 

 growths of scarlet and crimson seaweeds. The codfish, the cunner, 

 the sea raven, the rock-eel, and the wrymouth, which inhabit these 

 brilliant groves, are all colored to match their surroundings; the cod, 

 which has naturally the lightest color, being most brilliant in its 

 scarlet hues, while the others, whose skins have a larger original sup- 

 ply of black, have deeper tints of dark red and ruddy brown." "It 

 has occurred to me that the material for the pigmentary secretion is 

 probably derived indirectly from the algae, for, though the species 



