408 MISSOURI AGRICULTURAL EXP. STA V RESEARCH BULLETIN NO. II 



The results of the investigation are of further value in indicat- 

 ing that under proper feeding conditions, it might be possible to 

 raise even a Jersey cow with practically none of the characteristic 

 carotin and xanthophyll pigments in her body. 



DISCUSSION OF RESULTS. 



The results of the experiments reported in this paper are in 

 perfect accord with those of the preceding paper. The discovery of 

 the carotin and xanthophyll nature of the milk fat pigment would 

 lead quite naturally to the supposition that the other lipochrome pig- 

 ments of the body of the cow are of the same character. This sup- 

 position was fully borne out by the result of experimental study. 

 The yellow lipochromes of the body fat, of the corpus luteum and 

 of the skin secretions were found to be composed principally of car- 

 otin with one or more minor xanthophyll constituents. 



In addition to the establishment of the chemical relation of these 

 pigments to the carotin and xanthophyl of green plants in the case 

 of the body fat at least it has been possible to show that the pig- 

 ments are derived from the food in a manner identical with pig- 

 ments of the milk fat. The carotin and xanthophylls of the corpus 

 luteum and skin secretions must therefore be derived from the same 

 source. 



Viewing the results from a physiological standpoint, it is seen 

 that the establishment of such a source for these pigments and the 

 ease with which they are therefore increased and decreased, 1 throws 

 great doubt upon any physiological significance which these pigments 

 have been supposed to exert in the animal body. In the case of the 

 corpus luteum for instance, the accumulation of the carotin during 

 the formation of this body is merely a phenomenon incidental to the 

 rupture of the Graafian follicle and the subsequent formation of the 

 cellular tissue around the central blood clot, and to the fact that the 

 blood serum is normally very rich in carotin, as will be shown in 

 the following paper. This, of course, does not explain the mechanism 

 of the accumulation of the carotin-containing cells around the ruptured 

 Graafian follicle. The chemical combination of the carotin in the 

 blood serum is no doubt of importance in this connection. 



The popular opinion that the body fat of Jersey cows is nor- 

 mally characterized by a higher yellow color than Holstein cows has 

 been at le'ast partially confirmed by experimental study, although it 



1. This is especially true of the milk fat and, as will be shown in the 

 succeeding paper, the blood serum. 



