132 CAROTINOIDS AND RELATED PIGMENTS 



that no lipochromes are present. On the other hand the fact that the 

 pigment of butter fat appears in the unsaponifiable ether extractable 

 material at once classifies it as a chromolipoid. Palmer and Eckles 

 (1914a) were the first to make a critical examination of the pigment 

 from the standpoint of the plant carotinoids, finding, as might be 

 expected in the light of Escher's work on the corpus luteum pigment 

 of the cow, that the pigment corresponds exactly in physical and 

 chemical properties (spectroscopic, solubility and phase test) with 

 carotin. In addition we found, when the phase test and a chroma- 

 tographic analysis were applied, that small amounts of xanthophylls 

 usually accompany the carotin. These were most evident in highly 

 colored butter fat, a chromatogram in one case showing two and pos- 

 sibly three distinct adsorption zones of xanthophyll. The pigment 

 in each of these zones showed the xanthophyll absorption bands and 

 were hypophasic in the phase test between petroleum ether and 80 

 per cent alcohol. 



The character of the carotinoids in the milk fat of other animals 

 has not been determined. Palmer (1916) and Palmer and Kennedy 

 (1921) have noted the presence of carotinoid in traces in the milk fat 

 of sheep and goats without determining which kind of carotinoid is 

 present. We have also noted a complete absence of carotinoids from 

 the milk fat of albino rats and swine, even the fat of the colostrum 

 milk of the latter. 



The fat of human milk is always more or less pigmented, that of 

 colostrum being especially highly pigmented. Palmer and Eckles 

 (1914e) found both carotin and xanthophylls in about equal quan- 

 tities, as judged from the color of the solutions obtained in the phase 

 test when applied to the isolated pigment. Two samples of human 

 milk were examined, from different individuals, one sample being 

 colostrum. This result is to be expected in the light of what has been 

 found subsequently regarding the presence of both types of carotinoids 

 in human blood. 



Adipose tissue. The adipose tissue of cattle, horses and man is 

 characterized by varying amount of pigment, which at times attains a 

 high concentration in the horse, in certain breeds of cattle, such as 

 the Jersey and Guernsey dairy breeds, and at times in man. The 

 adipose tissue of other species of mammals, including sheep and goats, 

 dogs, cats, rabbits, swine, rats, guinea pigs and other rodents, is 

 entirely or almost entirely devoid of pigment. In the cases of pig- 

 mented adipose tissue of cattle Palmer and Eckles (1914b) found the 



