400 IV. WAXES, HIGHER ALCOHOLS, ETC. 



would appear to be the sole representative in physalien, capsanthin poses a 

 different problem. With the variety of fatty acids present in the latter 

 ester, it is almost certain that capsanthin is composed of a number of dif- 

 ferent mixed esters. 



5. Hydrocarbons 



Although hydrocarbons are frequently considered to be compounds 

 without biological significance in higher animals, there is an increasing 

 amount of evidence that they play an important role in the plant kingdom, 

 as well as in many marine forms. In contradistinction to the fatty acids 

 and higher alcohols, which are invariably composed of an even number of 

 carbon atoms, many of the hydrocarbons contain an odd number of carbon 

 atoms. Moreover, they frequently contain forked chains, Avhich is a type 

 of compound unusual in the other lipids. 



(1) Squalene 



Squalene is a highly unsaturated hydrocarbon with an empirical formula 

 of C30H50. An unsaturated hydrocarbon was first isolated from the liver oil 

 of a black shark of the genus Zameus'^-^; this was later shown to be 

 squalene. ^-^ It was found to be present in the liver oils of 16 of the 36 

 species of elasmob ranch fish, from Japanese waters, which were examined, *^^ 

 including the basking shark (Cetorhinus maximus) .^"^^ According to 

 Hilditch^* it is chiefly present in the liver oils of some of the family Squalidae 

 (sharks) as well as in some representatives of the other shark families, 

 Cetorhiriidae (basking shark), Chlamydoselachidae (frilled shark), Dalatiidae, 

 and the Scylliorhinidae (spotted dog fish) . It was found in the eggs of two 

 species in which it was also present in the liver oil. In this connection Heil- 

 bron et al^^^ have shown that it may be present in the comparatively unde- 

 veloped eggs of Etmopterus spinax, which is a member of the Squalidae; 

 however, it was not found in the mature eggs. This would seem to suggest 

 that it plays an important role in embryological development. Although 

 Channon^^" reported squalene in three of the Squalidae {Spinax niger, 

 Dalatias licha {Scymnorhiims lichia), and Lepidorhinus squamosus) , it was not 

 present in two other representatives of this family or in 11 members of 

 different elasmob ranch families. Channon also failed to find squalene in 

 any of 14 species of teleostid fishes or in any of a nimiber of phyto- and 



«* M. Tsujimoto, /. Soc. Chem. Ind. Japan, 9, 953 (1906). Cited by M. Tsujimoto, 

 Ind. Eng. Chem., 8, 890 (1916). 



«« M. Tsujimoto, Ind. Eng. Chem., S, 889-896 (1916). 



«' M. Tsujimoto, Ind. Eng. Chem., 12, 63-73 (1920). 



*28 M. Tsujimoto, Bull. Chem. Soc. Japan, 10, 144-148, 149-1.53 (1935); J. Chem.. Soc. 

 Japan, 55, 702-741 (1934); Chem. AbsL, 28, 6484 (1934). 



^29 I. M. IIeill)ron, E. D. Kamm, and W. M. Owens, .7. Chem. Soc, 1926, 1630-1644. 



"" H. J. Channon, Biochem. J., 22, 51-59 (1928). 



