go DISTRIBUTION IN NATURE IX 



2. VERTEBRATES 



a) Mammals 



A great deal of information is available in the literature concerning the 

 occurrence of carotenoids in mammals. Carotenoids have been found in nearly 

 every part of the mammalian organism. It is almost certain that these caro- 

 tenoids are derived from the vegetable feeding stuffs. It is not known, however, 

 whether the pigments undergo chemical changes in the animal body, or whether 

 they are stored unchanged. 



In the following sections the occurrence of polyene pigments in mammals 

 is described. The treatment given is not complete ; it is merely meant to illustrate 

 the manifold distribution of carotenoids in mammalian organisms. 



(i) Faeces 



Recent investigations have shown that part of the carotenoids taken with 

 the food leave the animal body unchanged^, while the rest is absorbed in the 

 intestine and then reaches the various organs. 



Cow dung^^^: Carotene, xanthophyll. 

 Sheep dung^^'': Xanthophyll( ?). 



It is noteworthy that on feeding a-carotene or /9-carotene to experimental 

 animals, only the same pigment is found in the faeces^^^. 



(ii) Blood serum^^^ 



A variety of carotenoids have been found in the blood serum of human 

 beings, horses, cows, calves, oxen, sheep, pigs, goats, cats and rats. The com- 

 position of the pigments depends on the diet fed to the animals. On the other 

 hand, no polyene pigments have been found in the sera of dogs, guinea pigs 

 and rabbits. 



Blood of pregnant ivomen^^'^: Carotene. Serum {human)^^^: ^-Carotene, lyco- 



Serum (cattlej^^i- Carotene, xantho- pene, ;5-hydroxycarotene( ?), 



phyll, cryptoxanthin. ^-hydroxyseniicarotenone( ?) xan- 



Seruni (human) ^^^i Carotene, lyco- thophyll, occasionally zeaxanthin. 



pene, xanthophyll. 



(iii) Fat tissues 



Bone marrow (humanj^^s, 329. Caro- Fat tissues (horses)^25- Carotene. 



tenoid. Fat tissues (human)^'": Carotene, lyco- 



Fat tissues (cats)^-*: Carotene, xan- pene, xanthophyll, capsanthin. 



thophyll. Intestine and subcutaneous fat (horses 



Fat tissues (cows)^". a-Carotene, ^-ca- and cattlej^ss; Xanthophyll. 



rotene. 

 References p. gg-io^. 



