CAROTINOID* /.V V///-: VERTEBRATES 129 



by applying the numerous macroscopic tests for this pigment evolved 

 by the plant biochemists, particularly Wills! litter and Mieg and 

 Tswett. This fact has recently been confirmed by van den Bergh 

 and Muller (1920) and by van den Bergh, Muller and Broekmeyer 

 (1920). In addition, Palmer and Eckles found that xanthophylls 

 eould also be demonstrated in small amounts in well-colored serum if 

 sufficient material (250-300 c.c.) was used. Neither type of carotinoid 

 was present in the blood of a newborn calf. 



After Hammarsten (1878) isolated crystalline bilirubin from horse 

 serum, it was believed for many years that this pigment was the sole 

 cause of the well-known golden yellow color of the serum of this mam- 

 mal. Gallerani (1904), however, found a lipochrome-like pigment 

 accompanying the bilirubin in horse serum, for which he proposed the 

 name plasmachrome. Van den Bergh and Snapper (1913), also, 

 found some lipochrome accompanying the bilirubin in horse serum. 

 The carotinoid identity of this lipochrome was shown a little later by 

 the writer (1916), using serum from a horse on bluegrass pasture 

 (rich in carotinoids). Carotin only was found, adsorbed on the albu- 

 min, as in the case of cattle serum, although the quantity present in 

 a unit volume was considerably less than was found in cattle serum 

 under comparable feeding conditions. Van den Bergh and Muller 

 and Broekmeyer (1920) have confirmed these findings, also, in so far 

 as the character of the carotinoid and the amount present are 

 concerned. 



Since Thudichum's (1869) early observation it has been recognized 

 that human blood serum may be colored by a lipochrome. Zoja 

 (1904) found that bilirubin is not present except under pathological 

 conditions. However, van den Bergh and Snapper (1913) state that 

 the serum of normal persons always contains a certain amount of 

 both lipochrome and bilirubin, sometimes one and sometimes the other 

 being in excess. They observed, also, that the scrum of diabetics may 

 contain extraordinarily large amounts of lipochrome, an observation 

 subsequently confirmed by Umber (1916), Biirger and Reinhart (1918, 

 1919), Salomon (1919), van den Bergh and Muller (1920), van den 

 Bergh, Muller and Broekmeyer (1920), and by Head and Johnson 

 (1921). Umber was able to shake the pigment out of the serum with 

 ether alone. Biirger and Reinhart (1918) suggested that the serum 

 pigment might be of exogenous origin and later (1919) presented 

 quantitative data showing a rise in the pigmentation of the serum on 

 a diet of green food. Salomon definitely identified as carotin the 



