FUNCTION OF CAROTINOIDS IN PLANTS, ANIMALS 271 



stated that "carotin of constant melting point through a number of 

 crystallizations was always found to induce growth in rats after growth 

 had been suspended by a lack of fat-soluble vitamin in the diet." It 

 is not stated how much carotin was fed. The statement is followed, 

 however, by the naive assertion that, "in spite of this it is not meant 

 to infer that the fat-soluble vitamin is necessarily a pigment." In the 

 same note, Steenbock and his associates state that they have prepared 

 crystalline acetyl derivatives of constituents in the non-saponifiable 

 vitamin fraction of the extracts from alfalfa hay, without resultant de- 

 struction of the vitamin. This fact alone is incompatible with a caroti- 

 noid nature for vitamin A. These pigments being hydrocarbons or 

 hydrocarbons with an ether-like nucleus are quite incapable of forming 

 acetyl derivatives. 



Some light on the cause of the coincident occurrence of vitamin A 

 and carotinoids is furnished by the recent experiments of Coward and 

 Drummond (1921) who find that the synthesis of vitamin A is associ- 

 ated with the formation of chlorophyll. Their results showing the pres- 

 ence of little if any fat-soluble vitamin in etiolated seedlings and red 

 sea-weeds, which are certainly not wanting in carotinoids, but which 

 lack chlorophyll, support our own conclusion that vitamin A and 

 carotinoids are not necessarily associated. The finding is of added 

 interest because it shows that examples of this lack of association 

 occur in the vegetable world as well as in the animal kingdom. 



These results when considered together with the results of Drum- 

 mond and Steenbock, as well as those of Palmer and Kennedy, show- 

 ing the lack of definite correlation between the carotin and vitamin 

 content of milk fat, indicate very clearly that the animals which trans- 

 fer carotin abundantly from the food to the milk, as well as those 

 which do not do so, have the power to separate pigment and vitamin. 

 The writer suggests that the presence of appreciable amounts of vita- 

 min A in the almost colorless butter fat examined by Steenbock may 

 have come from more or less yellow maize in the diet of the cows. 

 Palmer and Eckles (1914a) found that yellow maize has no appreciable 

 effect on the color of butter fat, but it should bolster up the vitamin 

 content of the butter, according to Steenbock's findings on the rela- 

 tive vitamin content of yellow and white maize. In an analogous man- 

 ner it should be possible to produce eggs with low pigmented yolks, 

 high in vitamin A, by limiting the pigmented part of the hen's ration to 

 carrots, for the writer (1915) has shown that the feeding of carrots 

 has little influence on the color of the yolks of hen's eggs. 



