COMPOSITION OF NATURAL FATS AND OILS 185 



acids, have been reported. ^^^ The fats from the higher land animals con- 

 tain more saturated acids, and stearic acid plays a more prominent role. 

 In the case of the unsaturated acids, both the marine and the terrestrial 

 animals possess many representatives between Cie and C24. However, the 

 aquatic forms have a much larger proportion of the longer chain com- 

 pounds, while most of the unsaturated fatty acids in the higher land forms 

 are concentrated in the C16 and Cig series. 



(a) Composition of Fats from Aquatic Forms. Strangely enough, there 

 seems to be a very considerable alteration in the type of fat which is found 

 in the salt-water and the fresh-water species. In general, the sea-water 

 forms are more complex and have high proportions of C18, C20, and C22 

 unsaturated acids. On the other hand, the fresh-water animals contain a 

 larger content of Cie and Cis unsaturated acids, with little C20 and practi- 

 cally no C22 acids. However, in both cases, the C20 and C22 acids which are 

 found are very highly unsaturated, containing from three to six unsaturated 

 linkages. Such differences cannot be shown to exist in the case of the 

 algae, in which the properties are in accordance with the color grouping 

 rather than with the origin. ^^'^ On the other hand, Lovern^" found that a 

 marked difference obtains between the fat of the marine form of copepod, 

 Calaniis finmarchicus, and that of a fresh-water copepod. This variation 

 in composition is shown by the loAver content of saturated acids, and of the 

 C16 and C18 unsaturated acids. A relatively large amount of C22 unsat- 

 urated acids occurs in the salt-water copepod but is practically absent from 

 the fresh-water forms. 



Marked differences in the composition of the fat of the marine and of the 

 fresh-water fishes have been demonstrated by the extensive studies of 

 Lovem^®^"^®^ and others. ^^''~^^- The fresh- water fishes have a practically 

 constant content of palmitic acid (20%) and an extremely high content of 

 C18 unsaturated acids (40% and more), while the figures for C20 and C22 

 unsaturated acids are lower than in the marine forms. Lovern^^^-'^^ has 

 suggested that the variation in composition of fresh-water and marine 



1" N. Nobori, /. Soc. Chem. Ind. Japan, 43, 59-60, 110, 340B (1940). 

 i«« J. A. Lovern, Biochem. J., 30, 387-390 (1936). 

 1" J. A. Lovern, Biochem. J., 29, 847-849 (1935). 

 ^«2 J. A. Lovern, Biochem. J., 31, 755-763 (1937). 

 »63 J. A. Lovern, Biochem. J., 32, 676-680 (1938). 

 1" J. A. Lovern, Biochem. J., 26, 1978-1984 (1932). 

 »«5 J. A. Lovern, Biochem. J., 30, 2023-2026 (1936). 

 i«« J. A. Lovern, Biochem. J., 28, 1955-1960 (1934). 

 »67 J. A. Lovern, Biochem. J., 29, 1894-1897 (1935). 

 i«8 J. A. Lovern, Biochem. J., 28, 1961-1963 (1934). 

 i« J. A. Lovern, Biochem: J., 30, 20-24 (1936). 



"" H. N. Brocklesby, Biol. Board Canada, Progress Repts., No. SO, 19-20 (1936). 

 "' H. N. Brocklesby and K. F. Harding, J. Fish Research Board Canada, 4, 59-62 

 (1938). 



"^ E. F. Armstrong and J. Allan, J. Soc. Chem. Ind.. 43. 207-218T (1924). 



