580 VI. OCCURRENCE OF LIPIDS IN THE ANIMAL 



may be greater in some laboratory animals, such as the rabbit and rat, 249 - 265 

 than in other species. Kraybill and associates 229 likewise noted a sex dif- 

 ference in the fat content of cattle. Thus, the average total fat content of 

 six Hereford heifers was found to be 30.5% as contrasted with a value of 

 25.9% for seven steers of the same species. 



(6) The Effect on Subcutaneous Fat. The higher content of fat in the 

 female than in the male is especially evident from the thickness of the sub- 

 cutaneous fat layer. In the case of human subjects, Wilmer 167 reported 

 that the subcutaneous layer of fat accounted for only 11.5% of the total 

 body weight in man and 23.7% of the total body weight in women. Similar 

 differences have been noted in the results based upon roentgenographic de- 

 termination of subcutaneous fat layers. In a group of one-hundred men 

 and one-hundred women whose average age was approximately thirty-eight 

 years, Reynolds and Asakawa 266 demonstrated a greater fat thickness in the 

 broadest portion of the calf in women (20.5 mm.) as compared with men 

 (10.8 mm.), while an opposite relationship obtained as regards the breadth 

 of the muscle (67.4 vs. 60.3 mm.) and that of bone (39.4 vs. 32.5 mm.). The 

 index of fat thickness to bone breadth was 27.6 for men and 62.2 for women. 

 Reynolds 267 reported that this sex variation appears early. Thus, the ratio 

 of fat thickness to bone index was found to be the following for males and 

 females, respectively: 7.5 yr., 44 and 51; 10.5 yr., 42 and 52; 13.5 yr., 38 

 and 51 ; 16.5 yr., 30 and 59; and young adults, 28 and 61. An examination 

 of Figure 4 will convince one that the sex variation in thickness of the 

 subcutaneous fat layer is generalized, and occurs at as early an age as 7.5 

 years. Keys and Brozek 166 state that the thickness of the subcutaneous 

 tissues in the Dutch population immediately after the liberation of Leiden 

 and of the Hague, as investigated by the Oxford Survey Team in World 

 War II was, on an average, 3.7 mm. for men and 5.4 mm. for women. 



Edwards 268 reported that skinfold measurements made at fifty-three sites 

 averaged 7.8 mm. for young men and 12.1 mm. for women. The latter 

 value for women is 155% higher than that for men. Edwards 268 showed 

 that men had relatively larger fat deposits on the trunk while, in the case of 

 women, the extremities and especially the legs, had the greater fat deposits. 



In a personal communication to Keys and Brozek, 166 from the Division of 

 Chronic Diseases and Tuberculosis of the U. S. Public Health Service, the 

 following average values were noted for skin-fold thickness in 103 negro 



265 C. M. Spray and E. M. Widdowson, Brit. J. Nutrition, 4, 332-353 (1950). 



266 E. L. Reynolds and T. Asakawa, Am. J. Phys. Anthropol, 8 (n.s.), 343-365 (1950). 



267 E. L. Reynolds, Human Biol., 21, 199-204 (1949). 



268 D. A. W. Edwards, Clin. Sci., 10, 305-315 (1951). 



