THE CHLOROPLAST PIGMENTS 



463 



OCCURRENCE OF CAROTIN AND XANTHOPHYLL 

 IN PLANTS AND ANIMALS 



Our attention will now be turned to the 

 occurrence of these pigments in the plant 

 and animal kingdoms. In the plant 

 kingdom carotinoids are to be found in all 

 of the plants which contain chlorophyll. 

 In many cases the pigments have not been 

 extracted and isolated but the evidence 

 for their presence is so great that the fact 

 cannot be denied. From the smallest 

 algae to the mightiest tree the carotinoids 

 are always present with chlorophyll. 

 The flagellates too unquestionably contain 

 these pigments, and they are even believed 

 to occur in some of the fungi. In general, 

 very little is known regarding their 

 presence in bacteria, though certain species 

 contain them. 



Evidence has been collected and pre- 

 sented by Palmer which shows that the 

 carotinoid pigments are widely distributed 

 in the vertebrates and in the invertebrates. 

 The yellow to orange-red animal pigments 

 which have been most commonly called 

 lipochromes are in all probability true or 

 modified plant carotinoids. In some 

 species both of the higher and of the lower 

 animals it is certain that the lipochromes 

 are true carotinoids, and it does not 

 require a very great stretch of the imagina- 

 tion to fill in the gaps . In fact the presence 

 of carotinoids in the animal kingdom is 

 much more common than those who are 

 not acquainted with the subject would be 

 led to believe. It would be very interest- 

 ing to list here all of the animals in which 

 the carotinoids have been found, but for 

 the purpose of this paper such a list is not 

 necessary. It will suffice to mention only 

 an example of each of the carotinoids . 



In i88z Kuhne first observed crystals of 

 the egg yolk pigments and decided that 

 these crystals were not identical with 

 those found in the corpus luteum of the 



cow. Willstattcr and Escher (191Z) 

 isolated the egg yolk pigment in sufficient 

 quantity for a chemical analysis. They 

 raised no query in their minds as to its 

 possible origin from plant carotinoids. 

 Escher 's work shows very clearly that he 

 saw no biological relationship between the 

 xanthophyll of the egg yolk and plant 

 xanthophyll, for he expressed the view 

 that "the oxygen-containing luteum in 

 the yolk of eggs plays the part of an 

 atavistic plant respiratory pigment for the 

 formation of hemoglobin in the embryo." 

 The chemical and physical properties of 

 the egg yolk pigment leave no doubt as to 

 its identity with the plant xanthophyll 

 which was isolated by Wills tatter and 

 Mieg (1907). In 1913 Escher definitely 

 established the chemical identity of the 

 corpus luteum pigment (of the cow) with 

 plant carotin. A possible chemical rela- 

 tionship between certain animal chromo- 

 lipoids and plant carotin was recognized 

 by several workers before this time. On 

 the other hand, many other workers saw 

 no evidence of a biological relationship 

 between plant and animal carotinoids. 

 Paulton (1893) has shown conclusively 

 that the color of caterpillars is largely due 

 to the plant pigments derived from the 

 food. In fact, it is now generally believed 

 that all phytophagous insects derive their 

 lipochromes and chlorophyll-like pig- 

 ments from their food. The work of 

 Palmer and his coworkers leaves no doubt 

 in the minds of students of the carotinoid 

 pigments that the carotin of butter fat, 

 adipose tissue, blood serum, skin secre- 

 tions, etc., of the cow is biologically 

 derived from the food and that a similar 

 relationship exists between the xantho- 

 phyll of egg yolk and fowl tissues and 

 plant xanthophyll. The view has now 

 become quite prevalent that all animal 

 chromolipoids are derived from the caro- 

 tinoids of the food and, either unchanged 



