428 MISSOURI AGRICULTURAL EXP. STA. RESEARCH BULLETIN NO. 12 



and body tissue, it became a matter of considerable importance to 

 ascertain how the blood carries these pigments through the body. 

 It has already been shown that there is a strong possibility that the 

 minor constituent of the pigment, i.e., the xanthophylls, are carried 

 in the serum dissolved in the fat. When considering such physiological 

 phenomena as the great volume of blood in circulation in an animal 

 as large as the cow and the rapidity with which it circulates, it 

 would seem very probable that even the very small percentage of 

 fat in the blood is sufficient to account for all the pigment, both 

 carotin and xanthophylls, which is presented to the milk glands and 

 body cells. On the other hand, when one considers the very large 

 proportion of carotin which is present in any given quantity of blood 

 serum of a cow receiving a ration rich in carotin, it must be concluded 

 that the fat plays little if any part in the transportation of this 

 pigment. The studies that are to be presented will, therefore, consider 

 only the carotin of the blood serum, since it is this pigment that com- 

 prises by far the greatest proportion of the lutein of the serum. 



It might be considered that the carotin is carried by the serum 

 merely in simple solution. In fact, Thudichum l stated that the lutein 

 of the blood is in solution in the serum. This seems to be very 

 probable especially in view of the fact that Krukenberg 2 found that 

 it could be extracted from the serum by means of amyl alcohol. 



Many facts can be presented, however, that go to show that 

 the carotin does not exist in the serum in simple solution. In the 

 first place neither carotin from plants nor the carotin of the serum 

 itself are, when isolated, taken up to any extent when treated with 

 the pure blood serum. Blood serum almost free from carotin from 

 natural causes, showed no indication of having taken up the carotin 

 in either case when poured over the pure amorphus pigments ; and the 

 serum itself showed no increase in the amount of color that could be 

 extracted by petroleum ether after dessication with plaster of Paris 

 and moistening with alcohol. 



In addition to the above the following observations were made : 3 



I. Five c.c. portions were shaken vigorously with equal volumes 

 of petroleum ether, ether, CS 2 and amyl alcohol respectively. All 

 extracts were colorless except in the case of the amyl alcohol which 

 was golden-yellow, and showed the carotin absorption bands both 



1. Loc. cit 



2. Loc. cit. 



3. Except where stated most of work about to be reported was done 

 with a golden-yellow, high-colored serum from Ayrshire cow No. 301. The 

 serum was obtained from this cow by drawing 250 c.c. of blood from the 

 jugular vein and allowing it to clot and the serum to press out. The serum 

 was free from red corpuscles. 



