558 VI. OCCURRENCE OF LIPIDS IN THE ANIMAL 



human body, on the basis of data of Behnke and associates. 187 Keys and 

 Brozek state that the value should have been 1.098, and should refer to a 

 human body containing 10% of its weight as essential lipids. 



The specific gravity of human subcutaneous fat, as given by Ulzer and 

 Klimont, 188 was 0.9179 at 15°C. Fidanza, Keys, and Anderson, 189 on the 

 basis of determinations of the densities of twenty samples of fat from adult 

 men and women, obtained values ranging from 0.8982 to 0.9009, with an 

 average value of 0.9000/g. at 37 °C. The mean change in density of human 

 fat from 15° to 37°C. per 1°C. was found to be 0.00074; it was quite uni- 

 form over this temperature range. At 15°/15°C, the specific gravity was 

 0.9171, which approximates a value (0.9179) cited earlier by Jaeckle, 190 as 

 well as that of Ulzer and Klimont. 188 The density of dog body fat was 

 found to be lower than that of man, but in other species the values for the 

 density of the body fat are higher than in the case of man. 189 Tester 191 

 showed that a linear relationship exists between the oil content of the 

 Pacific herring (Clupea pallasii) and a factor based upon specific gravity. 

 Rathbun and Pace 186 proved that a similar phenomenon occurs in the 

 guinea pig. On the basis of studies of fifty guinea pigs the specific gravity 

 of whose eviscerated bodies ranged from 1.021 to 1.096, and whose fat con- 

 tent varied from 1.5 to 35.8%, the following formula was derived to calcu- 

 late the body fat of these animals from the specific gravity: 



% fat (guinea pig) = 100 (^j - 4.88o) 



In order to apply the same formula to man, Rathbun and Pace modified 

 the preceding formula as follows : 



% fat (man) = 100 (^® - 5.044^ 

 \sp. gr. / 



Kraybill et al. 192 showed that, in the case of swine, the fat content can be 

 accurately calculated, by the following formula, from the specific gravity of 

 the eviscerated animal : 



187 A. R. Behnke, B. G. Feen, and W. C. Welham, J. Am. Med. Assoc, 118, 495-498 

 (1952). 



188 F. Ulzer and J. Klimont, Allgemeine und physiologische Chemie der Fetle,fur Chemi- 

 ker, Mediziner, und Industrielle, Springer, Berlin, 1906; cited by A. Keys and J. Brozek, 

 Physiol. Revs., 88, 245-325 (1953), p. 271. 



189 y. Fidanza, A. Keys, and J. T. Anderson, The Density of Human Body Fat, in 

 press; cited bv A. Keys and J. Brozek, Physiol. Revs., 88, 245-325 (1953), p. 271. 



190 H. Jaeckle, Z. physiol. Chem., 86, 53-84 (1902). 



191 A. L. Tester, J. Fisheries Research Board, Can., 4, No. 5, 461-471 (1940). 



192 H. F. Kraybill, E. R. Goode, R. S. B. Robertson, and H. S. Sloane, /. Applied 

 Physiol, 6, 27-32 (1953). 



