CAROTINOIDS IN THE VEKTEH KATES 131 



the bands when using an instrument of high dispersion equipped for 

 measuring the wave-length positions of the band-. 



A word may be said here regarding the state of carol inoids in 

 blood. Van den Bergh and Muller (1920) assert that neither carotin 

 nor xanthophylls can be shaken out of blood serum with ether. Tiny 

 believe that the pigments are always in colloidal solution in the 

 plasma. The writer is in accord with this view in so far as carotin 

 in ox and horse serum is concerned, and at times for human serum. 

 It is believed, however, that in all probability a double colloidal 

 phenomenon is involved in these cases, i.e., first, a colloidal adsorption 

 of the carotin by albumin and second, a colloidal solution of this albu- 

 min in the plasma. As for xanthophyll in blood serum, the writer 

 merely wishes to state that he has never failed to secure its direct 

 extraction with ether when present in the serum of animals, and 

 accordingly does not feel justified in believing that colloidal phe- 

 nomena are involved in any way. The explanation for this differ- 

 ence offers an interesting problem in biochemistry. 



Observations are very scanty on the pigment of the blood scrum 

 of other mammals. The writer (1916) examined the blood of each of 

 three breeds of swine, representing the Duroc-Jersey, Poland China 

 and Berkshire breeds at a time when they were on pasture, but failed 

 to detect the presence of even traces of carotinoid or other chromo- 

 lipoid-like pigment. In a similar manner the blood of each of five 

 breeds of sheep, namely, Dorset, Hampshire, Merino, Shropshire and 

 Southdown, showed the presence of only traces of chromolipoid, which 

 appeared to be carotin, although the animals, like the swine, were 

 receiving an abundance of carotinoid-rich pasture grass at the time. 

 The blood of an Angora goat, under like feeding conditions, showed 

 traces of carotinoid also. Van den Bergh, Muller and Broekmeyer 

 (1920) likewise found no carotinoids in the blood serum of swine, 

 guinea pigs or dogs, and traces only in the blood serum of cats. In 

 the case of the latter animal, xanthophyll practically disappeared 

 from the blood within a half hour after an intravenous injection of a 

 colloidal solution of xanthophyll. It is stated that the pigment was 

 found, however, in the liver. 



Milk fat. Thudichum's classic paper included the pigment of 



butter fat among the "luteins." Blythe (1879), however, regarded 



the alcohol soluble lactochrome which he isolated from milk whey as 



the cause of the butter fat color, and Desmouliere and Gautrelet 



'* (1903) concluded, after isolating a urobilin-likc pigment from milk, 



