SOURCES OF FAT IN ANIMAL BODY 527 



posited in the tissues. The same situation also obtains in the case of the 

 caproyl radical (C 6 ), 28 and likewise of the caprylyl group (C 8 ). 29 



Powell reported, however, that capric acid (C ia ) was laid down to the ex- 

 tent of 15% in the storage fat after the administration of tricaprin, 30 

 while trilaurin (Ci 2 ) is likewise capable of being stored. In her tests, 

 Powell 29 proved that the saponification number of the deposited fat was 

 increased from 199 to 218 by the administration of trilaurin, which would 

 indicate that approximately 25% of the short-chain acids were present in 

 the storage depots. Channon et al. n were able to produce somewhat 

 similar results in rats by the administration of a diet containing 40% of 

 coconut oil. After twenty-one days, the depot fats contained 1.2% of 

 capric acid (Cio), 17.2% of lauric acid (Ci 2 ), and 13.8% of myristic acid 

 (d 4 ). Longenecker 32 confirmed these results in rats fed high coconut oil 

 rations for fourteen days. The depot fat was found to contain as much as 

 31.8 mole per cent of lauric acid (C ]2 ) and 18.1 mole per cent of myristic 

 acid (Ch), as contrasted with a palmitic acid (Cie) content of 18.6 mole per 

 cent. Although myristic acid ordinarily comprises only 1% or less of the 

 total fatty acids in the rat, 32 the results obtained by Channon et al. 31 and 

 by Longenecker 32 confirm the earlier results of Eckstein, 26 which indicated 

 that a large amount of myristic acid was laid down in the tissue lipids 

 after its administration. Lovern 33 also reported that the administra- 

 tion of ethyl myristate to eels was followed by an increased tetradecenoic 

 acid content, in the eel fat, but that no increase in myristic acid obtained. 

 However, an increase in both palmitic and hexadecenoic acids occurred in 

 the eel body fat after the administration of ethyl palmitate. 



b. The Effect of Fats Containing Fatty Acids with an Odd Number of 

 Carbon Atoms on the Composition of Storage Fat. Natural vegetable and 

 animal fats invariably contain only fatty acids having an even number of 

 carbon atoms. With the exception of the formic acid residue and that of 

 propionic acid (C 3 ) , the odd-carbon fatty acids can largely be considered as 

 unphysiological compounds. Whereas the even-chain fatty acids give rise 

 to ketone bodies, 34 and no glycogen deposition follows their administration, 35 



28 H. C. Eckstein, J. Biol. Chem., 84, 353-357 (1929). 



29 M. Powell, J. Biol. Chem., 89, 547-552 (1930). 



30 M. Powell, J. Biol. Chem., 95, 43-45 (1932). 



31 H. J. Channon, G. N. Jenkins, and J. A. B. Smith, Biochem. J., 81, 41-53 (1937). 



32 H. E. Longenecker, /. Biol. Chem., 130, 167-177 (1939). 



33 J. A. Lovern, Biochem. J., 84, 704-708 (1940). 



34 H. J. Deuel, Jr., L. F. Hallman, J. S. Butts, and S. Murray, J. Biol. Chem., 116 

 621-639 (1936). 



35 H. J. Deuel, Jr., J. S. Butts, L. F. Hallman, and C. H. Cutler, J. Biol. Chem., 112, 

 15-23 (1935). 



