190 CAROTINOIDS AND RELATED PIGMENTS 



tionship between plant and animal carotinoids in 1912 in order to 

 explain the quantitative variations in the pigmentation of butter fat 

 due to changes in the ration of the cow. A study of the chemical and 

 physical properties of the butter fat pigment had shown it to be iden- 

 tical with carotin, regardless of the extent of the pigmentation of the 

 butter fat from which the pigment was isolated. The more highly 

 tinted fats, however, showed the presence of small amounts of xantho- 

 phylls associated with the carotin when the total pigment was exam- 

 ined by means of the phase test or analyzed by means of a Tswett 

 chromatogram. When these facts were viewed in the light of the dis- 

 tribution and amount of carotinoid pigments in the usual dairy cattle 

 foods, and when numerous data on the variations in the color of butter 

 fat under known feeding conditions were interpreted with these facts in 

 mind the conclusion was inevitable' that the carotinoids of butter fat 

 are derived from the carotinoids of the food. This conviction was 

 strengthened further by a study of the character of the pigment of 

 the adipose tissue, skin secretions and especially the blood serum of 

 dairy cattle showing that the pigment in each case is chiefly carotin, 

 with which a small amount of xanthophyll is usually associated. The 

 preliminary statement of Willstiitter and Escher (1912), published 

 during the course of these studies, that the corpus luteum pigment of 

 the cow is also carotin (an observation which we were able to con- 

 firm), lent additional support to the theory of a biological relationship 

 between the lipochromes in cattle and the carotinoids of their ration. 

 The correctness of this theory was shown by varying the content 

 of carotinoids in the ration of the cow through the proper selection 

 of foods deficient in carotinoids or containing an abundance of these 

 pigments and observing the quantitative variations in the amount 

 of pigment in the blood serum and butter fat. These experiments were 

 supplemented by an examination of the character of the pigment in 

 the blood and butter. In addition two dairy cows of the Jersey breed, 

 whose adipose tissue is normally highly pigmented with carotin, were 

 fattened on rations respectively rich and poor in carotin after a pre- 

 liminary period of sixty days on straw alone. Some of the data 

 secured in the experiments designed to show the biological relation 

 between the carotin content of the blood serum and milk fat and that 

 of the ration are given in Table 14. Table 15 shows the effect on the 

 color of the adipose tissue in certain parts of the body of Jersey cattle 

 which results when partially starved animals are fattened on rations 

 deficient or rich in carotin. 



