CAROTIN, THE PRINCIPAL YELLOW PIGMENT OF MILK FAT 435 



sulphate, but is no longer soluble in water after being coagulated by 

 heat or alcohol. 1 The protein is not coagulated by saturation of its 

 solution with sodium chloride. 



Not very much can be said in regard to the character of the 

 combination of the carotin with the albumin The combination is evi- 

 dently a firm one, and is broken down only in the presence of alcohol 

 so that the pigment can be extracted by ether or petroleum ether. The 

 union is also broken down by dialysis, or at least rendered less firm, 

 but is not broken down when the protein is precipitated as a lead, silver 

 or mercury salt. It is interesting to notice that cholesterol and a phos- 

 phorus-containing body (probably lecithin) are mixed up in some way 

 in the combination of albumin and carotin, the liberated carotin from 

 the dialysed pigmented albumin yielding both cholesterol and phospho- 

 rus. We propose the name caroto-albumm or luteo-albumin for the 

 chromo-protein which transmits the carotin from the food to the milk 

 glands and fat synthesizing body cells of the cow. 



The finding of this highly unsaturated hydrocarbon carotin pig- 

 ment in combination with one of the albumins of the blood, probably 

 similar to the combination of the haematin in the haemoglobin of the 

 red blood corpuscles, at once raises some impiortant questions as to 

 a possible physiological significance which might be attached to the 

 presence of the pigment. One can only suggest that like the haemo- 

 globin the luteo-albumin may be of importance in connection with the 

 oxygen supply of the body. This is not probable. The ease with which 

 the carotin is increased and decreased in the blood serum as shown by 

 the feeding experiments, seems to preclude the possibility of the 

 carotin being absolutely essential to the life of the cow. 



A STUDY OF THE HIGH COLOR OF COLOSTRUM MILK FAT. 



Considerable data was given in the preceding Bulletin of this series, 

 which showed that colostrum milk fat from all breeds of cows is 

 characterized by a very high content of carotin. In view of the results 

 obtained in the study of the pigment of the blood serum, it seemed 

 very probable that this interesting phenomenon was due to a great 

 accumulation of the carotin in the blood serum just previous to par- 

 turition. In order to obtain some definite experimental evidence in 

 support of this supposition, blood was drawn from the jugular vein of 

 a pure bred Jersey cow (No. 23), when she was dry and three days 

 previous to parturition. The amount of color in 10 c.c. of the blood 



1. After standing a short time under the alcohol. 



