CAROTIN, THE PRINCIPAL YELLOW PIGMENT OF MILK FAT 397 



The orange-yellow carbon bisulphide solution was now analyzed 

 chromotographically. Only one pigment was present, which passed 

 through the column very slowly as a narrow orange zone, leaving 

 no pigment in the CaCO 3 which could be washed out with alcoholic 

 petroleum ether. 



TABLE 2. ABSORPTION BANDS OF CAROTIN AND XANTHOPHTTLLS OF BODY FAT. 



It must necessarily be concluded from these experiments that 

 Newbigin's "inert" class of lipochromes does not exist in the body 

 fat of the cow, but, on the other hand, the pigment of this fat is, like 

 the butter fat pigment, composed of a major carotin and one or more 

 minor xanthophyll constituents, all of which also show the proper- 

 ties of lipochromes. It is to be noted also that the number of xan- 

 thophylls in the body fat varies, as was found to be the case in the 

 butter fat studies. 



The Relation Between the Cofor of the Body Fat and the Food of the Cow. 



Numerous feeding experiments in connection with the study 

 of the pigment of milk, reported in the preceding paper of this series, 

 showed that the carotin and xanthophylls which were found to char- 

 acterize the milk fat were present there on account of the fact 

 that the food contained these pigments. Since the pigment of the 

 body fat is also composed of carotin and xanthophylls it is natural 

 to suppose that it is, like the pigment of milk fat, derived from the 

 food, the carotin and xanthophylls being carried to the fat depots and 

 fat synthesizing body cells in the same manner that they are carried to 

 the milk glands. 



In order to obtain evidence of this fact, however, the following 

 experiment was undertaken. Two barren and dry Jersey cows in 



