130 CAROTINOIDS AND RELATED PIGMENTS 



pigment which he extracted from high colored human serum. Of 

 interest is his observation that in this case direct extraction with 

 ether took out very little pigment, it being necessary first to precipi- 

 tate the proteins with alcohol and extract the precipitate with ether. 

 Apparently this investigator regarded the presence of the carotin as 

 fortuitous, for he mentions the difficulty in distinguishing the pig- 

 ment from the normal lipochrome of the blood. 



It is obvious that none of the workers mentioned in the preceding 

 paragraph were familiar with the observations of the writer on the 

 character and cause of the normal chromolipoid of cattle and horse 

 serum. It remained for Hess and Myers (1919) to show the direct 

 application of the writer's observations on animals to the variations 

 in the pigmentation of human blood serum, by demonstrating marked 

 variations in the carotin- content of the blood serum of children with 

 variations in the carotin content of their diet. These observations 

 have been extended greatly by van den Bergh and Muller (1920) and 

 van den Bergh, Muller and Broekmcyer (1920) who have shown that 

 both carotin and xanthophylls play a part in causing the normal pig- 

 mentation of human blood serum, sometimes one and sometimes the 

 other predominating, although carotin is usually in excess. 



The writer has recently observed an interesting case of marked 

 change in the character of the carotinoid in the blood serum of an 

 adult. At the time of the first examination the serum was colored 

 almost exolusivelv bv carotin, which could not be shaken out of the 







blood with ether. At this time carrots played a large part in the diet. 

 At the time of the second examination the pigment was readily ex- 

 tracted simply by shaking the serum with ether. The character of 

 the diet was not ascertained in this case, although a similar pigment, 

 readily extracted by ether, was found abundantly in the blood of two 

 other persons on a diet rich in green foods (spinach and green string 

 beans). By analogy with the writer's (1915) experiments with the 

 pigment of fowl serum this pigment should have been xanthophyll. 

 However, a phase test applied to the pigment in each case showed 

 that it was almost quantitatively epiphasic between the petroleum 

 ether and 80 per cent methyl alcohol. Inasmuch as this property is 

 supposed to be distinctly characteristic of carotin, it appears that the 

 character of the diet may influence the manner in which carotin is 

 carried by human blood. In each case the serum extracts showed 

 two-banded absorption spectra when using a spectroscope with nar- 

 row dispersion, but it was not possible to secure the measurements of 



