12 



build: definition and ontogeny. 



of age. It then slowly increases to maturity, and indeed to 30 years, 

 after which it increases with extreme slowness, probably to 55 years. 

 From table 4a and the curve of build, figure 2, we see that the infant 

 at birth has a chest-girth which is somewhat over two-thirds of 

 stature (0.6685). It falls rapidly to one month after birth, and then 

 begins to rise. This minimum is connected with the loss of weight 

 which follows birth, and is due to the difficulty of making adjustments 

 to the new conditions which the organism has to meet. This adjust- 

 ment is soon thereafter completed and within 2 months chest-girth 

 and weight are not only recovered, but have caught up with increasing 

 length of body. At 6 weeks the body has reached its maximum 

 post-natal chubbiness. Another temporary loss in chubbiness occurs 



690 

 670 

 650 

 630 

 610 

 590 

 570 

 550 

 530 

 510 

 490 

 470 



~~1 i _ I i 1 I i 



c 



v 1 — 



10 



12 



16 



18 



20 



22 



»4 25 

 Years 



Fig. 1. — Polygon of development of relative chest-girth, male. 



Abscissae: Age in years. Ordinates (chest-girth -r stature) X 1000. Based on averages of 

 the measurements of Quetelet (Belgians), Weissenberg (Russian Jews), Benedict and 

 Talbot (U.S.A.). Masters Day Nursery, N. Y. City, Town (Iowa children). Gray and 

 Jacobs (school boys, well-to-do), Reitz (Germans), Godin (French), Hitchcock (U. S. A. 

 college men), Baldwin (N. Y. City schools). 



at about 8 months, due perhaps to the cutting of the incisors. The 

 decline which subsequently ensues is prevailingly due to the rapid 

 growth of the legs without corresponding increase in transverse 

 diameter (plates 3 and 4). At about 12 years the boy enters the 

 awkward age when, his legs and arms having grown from 5 to 10 cm. 

 in a single year, he has not yet acquired muscular control of them 

 (plate 7, fig. 2). At the same time his trunk retains childish propor- 

 tions (plate 5, fig. 12). A little earlier than the boy, the girl enters 

 the "Backfisch" stage of similar slenderness and awkwardness (plate 

 7, fig. 3, from Stratz, 1922, p. 258). It is commonly believed that 

 this rapid growth of the appendages and their long bones is controlled 

 by the secretions of the pituitary gland. Gradually in the boy, at 

 14 years, as the gonads begin to ripen, the growth of the legs is 

 retarded and the transverse chest diameter begins to increase rapidly; 



