Body densities and skinfold thicknesses of 105 boys and 89 girls aged 9 to 14 years were measured, and the regression equations for predicting the body density from the skinfolds were proposed. Body density was determined by the water displacement volumetry. The skinfold thicknesses were measured at two sites of triceps and subscapula by using an Eiken-type Caliper (devised in our Institute) calibrated to exert pressure of 10gm/mm2. The average values of body density in boys were 1.0621 for 9-11 years old and 1.0566 for 12-14 years old and in girls were 1.0490 for 9-11 years old and 1.0523 for 12-14 years old (Table 2). The correlation coefficients between body density and skinfolds were similarly higher in correlation with the triceps skinfold and the combined skinfold of [triceps+subscapula] and with the skinfold index expressed as [skinfold×body surface÷body weight], as compared with the low coefficient values in subscapular skinfold. The correlations between body density and physique indices of W/H2 and W/H3 were lower as compared with the coefficients in the skinfolds (Table 3). The regression equations for predicting the body density from the skinfolds are given in Tables 4, 5 and 6. Among these equations, equation No. 3 for boys and No. 7 for girls are simpler and useful, and equations No. 4 and No. 8 by using the skinfold index are more reliable. The reliability by using the skinfold index lies in eliminating the erroneous element under the influence of individual difference of body height or muscular mass in estimation of the body density and body fat content by the simple use of skinfolds.
The relation of morbidity of permanent teeth saprodontia and intake of nutrients of inhabitants Kuzakicho, Toba City, a farm-fishing village with a low morbidity rate and in Mori-district, Iidakacho, fountain village with a high morbidity were investigated. Morbidity of saprodontia in permanent teeth of students of the Kuzaki elementary school was 20.0% in the 5th year and 28.6% in the 6th year students. The average number of saprodontia per person was 0.20% and 0.36% in 5th and 6thyear students, respectively. By contrast, in the Mori elementary school, the morbidity rate in the 5th year student was 92% and 93% in the 6th year, the average number, 3.29% and 5.73%, respectively. A remarkable difference between morbidity in both districts, was found and the same tendency was also observed in number of saprodontia at C3-C4. 1) Investigation on conditions of the intake of both districts revealed that the intake of animal protein was over 32% the standard value for 1975 (M: 42.5g, d: 13.39, CV: 31.5%) in Kuzakicho and 25% lower than that (M: 24.0g, S: 4.99, CV: 20.8%) in Mori-district, Iidakacho. Intake of calcium appeared to be satisfactory (M: 0.62g, d: 0.073, CV: 11.8%) in Kuzakicho, but was 23% lower (M: 0.47g, δ: 0.14, CV: 29.8%) in Mori-district, Iidakacho. Carbohydrate and salt intakes were higher in Mori-district than in Kuzakicho. 2) A large amount of fish, shellfish, seaweeds and beans were taken in Kuzakicho seemed to be recommendable, however, in Mori-district an excess amount of sweets, cakes and pickled vegetables was observed.