DURING POST-NATAL DEVELOPMENT. 539 



1. The chief changes in the height-weight index associated with alterations in 

 the proportions of the body during post-natal morphogenesis have been discussed 

 above. They may be briefly summarized as follows: (a) First half-year after birth, 

 infancy, rapid growth but relatively slight change in bodily proportions. (6) From 

 this period to puberty, childhood, growth of limbs rapid, head slow, trunk inter- 

 mediate, height-weight index greatly reduced, (c) Puberty to maturity, adoles- 

 cence, growth of trunk and limbs at first about equal in the male, followed by a 

 relatively more rapid growth of trunk. Growth in thickness of trunk continues 

 longer than growth in length. During the first part of this period the index changes 

 little, during the latter part it is increased, (d) Period of relatively stable proportions, 

 maturity. Some increase in thickness of muscles during the early part of this period 

 and of fat in the latter part usually causes a gradual increase in height-weight 

 index during maturity, (e) Period of decline, old age. Loss of fat and musculature, 

 decrease in stature and in relative length of spine. Decrease in index. 



2. Sexual peculiarities are relatively -small preceding puberty, although at the 

 same age girls are usually somewhat smaller than boys in stature and build and 

 have a slightly smaller index until the period immediately preceding puberty, when 

 girls usually exceed boys in height, weight, and index. In girls at the time of puberty 

 the trunk is elongated in the lumbar region and the pelvis is enlarged, while the 

 lower extremities cease to grow proportionately with the trunk. Growth in stature 

 ceases earlier than in boys and increase in width of trunk, except in the pelvic region, 

 is less marked than in boys during the latter part of adolescence. Women have rela- 

 tively bulkier thighs and calves than men ; compared with men of the same height 

 women usually have slightly longer lower extremities. The height- weight index is 

 increased during the period of relative lengthening of the trunk and increase in size 

 of the pelvic region and thighs. Increase in index due to increase in width of 

 skeleton and musculature during adolescence is much less marked in women than 

 in men, but increase in index due to adiposity is apt to be more marked, especially 

 in the latter part of the period of maturity. 



3. There have been numerous attempts to classify variations in bodily propor- 

 tions into various types. Bean (1912) has endeavored to subdivide the human 

 species into three main subdivisions from the standpoint of proportions of the 

 body, the hypo-onto-morph, the meso-onto-morph, and the hyper-onto-morph. In 

 the first, maturity comes on relatively early in the life-cycle, so that to a con- 

 siderable extent the proportions of the child are preserved in the adult, large head, 

 small face, long trunk, short lower limbs. According to Bean, it is a type charac- 

 teristic of Asiatics and Filipinos. To some extent the data of Bobbitt (1909) appear 

 to support Bean's views. On the other hand the marked increase in relative 

 sitting-height, which takes place in these races after puberty, suggests an extension 

 of the adolescent lengthening of the trunk at the expense of the pre-adolescent 

 lengthening of limbs. Since the lower limbs in this type are relatively short, the 

 height-index is relatively high in well-nourished individuals. The meso-onto- 

 morph (according to Bean's descriptions) appears to come to maturity at a period 

 corresponding to late childhood or early adolescence, a time when the limbs are 



