LIPID CONTENT AND COMPOSITION OF ANIMAL 589 



of unsaturated acids (and hence a lower melting point) are produced in cold 

 environments, while those produced in tropical or semitropical districts 

 tend to have a higher proportion of saturated acids (and hence higher melt- 

 ing points). However, Hilditch 116 points out that some of the most highly 

 unsaturated fats come from plants indigenous to the tropical or subtropical 

 areas. Although it is improbable that fats solid at the prevailing tem- 

 peratures would be produced by plants in the cooler districts, Hilditch does 

 not consider that the evidence proves that high environmental tempera- 

 tures per se cause or favor the production of more saturated fats. It is 

 true that the seed oils from plants grown in either cold or hot climates have 

 a greater proportion of characteristic unsaturated acids than do those pro- 

 duced in plants raised in areas where the environmental temperatures are 

 intermediate between these extremes. 



There are numerous instances in which oils from the seeds of species in- 

 digenous to cool climates have been shown to be more unsaturated than are 

 those from warmer districts. This is true in the case of seeds from the 

 several varieties of pine (Pinus). 30i ~ 312 The same relationship has been 

 shown to exist in the seed oils of the Moraceae (mulberry family) ; the oil 

 from hempseed {Cannabis sativa), which grows in temperate zones, is more 

 highly unsaturated than is the seed oil from the African variety of bread- 

 fruit (Trecalia africana), 313 ~ 315 which is native to the more tropical Sierra 

 Leone. 316 Another example of a similar variation occurs in the seed oils 

 from the bittersweet; the variety indigenous to North America (Celastrns 

 scandens) 317 contains more linoleic and linolenic acids and less oleic and 



304 S. L. Ivanov and S. B. Resnikova, Schriften zentral. biochem. Forsch.-Inst. Nahr. u. 

 Genussmittelind. (U. S. S. R.), 3, 239-245 (1933); Chem. AbsL, 28, 2557 (1934); cited 

 by T. P. Hilditch, The Chemical Constitution of Natural Fats, 2nd ed., p. 156. 



306 A. Eibner and F. Reitter, Chem. Umschau Gebiete Fette, Ole, Wachse, u. Harze, 33, 

 114-124, 125-129 (1926); Chem. AbsL, 20, 3243 (1926); cited by T. R Hilditch, The 

 Chemical Constitution of Natural Fats, 2nd ed., p. 156. 



306 O. von Friedrichs, J. Soc. Chem. Ind., 39, 304 A (1920). 



307 0. von Friedrichs, Svensk Farm. Tidskr., 23, 445-451, 461-463, 500-505 (1919); 

 Chem. AbsL, 14, 205-206 (1920). 



308 G. V. Pigulevskil and M. A. Ivanova, J. Applied Chem. (U. S. S. R.), 7, 569-571 

 (1934); Chem. AbsL, 29, 2007 (1935). 



309 M. Adams and A. Holmes, Ind. Eng. Chem., 5, 285-287 (1913). 



310 J. Semb, J. Am. Pharm. Assoc, 24, 609-613 (1935). 



311 A. H. Gill, Oil & Soap, 10, 7-8 (1933); Chem. AbsL, 27, 1223 (1933). 



312 H. Matthes and W. Rossie, Arch. Pharm., 256, 289-302 (1918). 



313 H. N. Griffiths and T. P. Hilditch, ./. Soc. Chem. hid., 53, 75-81 T (1934). 



314 H. P. Kaufmann and S. Juschkevitsch, Z. angew. Chem., 43, 90-92 (1930). 



316 P. Shestakov and P. Kupchinsky, Z. deut. Ol.-Fett-Ind., 42, 741-743, 774-776 

 (1922); Chem. AbsL, 17, 889 (1923). 



316 M. B. Ichaporia, Dissertation, Liverpool, 1937; cited by T. P. Hilditch, The Chemi- 

 cal Constitution of Natural Fats, 2nd ed., Wiley, New York, 1947, p. 162. 



317 C. Barkenbus and C. F. Krewson, /. Am. Chem. Soc, 54, 3993-3997 (1932). 



