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Male and female ckicks of Rhode Island Red with normal growth were used for this study. The carcass without the head, feather, feet, skin, viscera and abdominal fat was divided into three large parts, namely the body stem's, the forelimbs' and the hind legs' part, respectively. Moreover, each part was divided into bone, fat and muscle, and those weights were measured respectively. Postnatal growth of each part was compared, and differences between both sexes were studied. The results obtained were as follows: 1. In the total weight of each part, the forelimbs' part of both sexes grew and developed very rapidly during the first 2 weeks. And thereafter in the female, growth and development of the forelimbs' and the hind legs' parts were alike, but that of the body stem’s part was worse than the other. On the other hand, growth and development of the hind legs' part was a little better than the forelimbs', and that of the body stem's part was worst from 2 to 22 weeks old in the male. Unique growth of the hind legs' part was observed during sex-maturing period only in the male. 2. The forelimbs' bone of both sexes grew and developed more rapidly than the other during the first 2 weeks. But, the hind legs' bone grew and developed more rapidly after 2 weeks old. The bone of each part was earlier-maturing than the fat and the muscle. 3. The fat weight of each part of the male was nearly constant as percentage of dressing body weight, and that of the female increased a little during sex-maturing period. The body stem' s and the forelimbs' fat increased more than the hind legs'. The fat of the hind legs' part was earlier-maturing. Considerable amount of the fat was deposited in the hind legs' part from the early days. 4. Growth of the muscle was divided into four periods as follows: I-period (0-2 weeks old) : The forelimbs' muscle of both sexes grew and developed very rapidly. II-period (2-22 weeks old): In the female, growth of the forelimbs' and the hind legs' muscle were alike. In the male, growth of the hind legs' muscle was a little better than that of the forelimbs'. III-period (22-26 weeks old): In the female, the muscle weight of each part grew and developed only a little during this period. On the other hand, that of the hind legs' and the body stem's parts grew and developed particularly in the male. IV-period (after 26 weeks old): Muscle grew to about its completion, and the composition of muscle was nearly stable. Rapid growth and development of the forelimbs' muscle was observed in the both sexes from hatching to 2 weeks old, and this is seemed to recover backwardness of growth in this part at birth. Unique growth and development of the hind legs' and the body stem's muscles, supposed to be sex-characteristics, were observed during sex-maturing period in the male.