Abstract THE work of Schunck (1903), Palmer and Kempster (1919), Kuhn and Grundmann (1933), Brockman and Volker (1934), and Gillam and Heilbron (1935) shows that the carotenoid pigments present in egg yolk consists almost entirely of xanthophyll with only a small amount of cryptoxanthin and carotene. So far no experiments have been reported which give quantitative data concerning the relation of the amounts of these carotenoid pigments in the feed to the amount of these pigments in the egg yolk. This paper presents the results of two experiments which give some data on this quantitative relationship. In the first of these experiments the source of the pigments was kept constant while the amount in the rations varied, in the second experiment the amount of pigments in the ration was kept constant while the source of the pigments was varied. EXPERIMENT I The object of this experiment, which was conducted in the . . .