DURING POST-NATAL DEVELOPMENT. 515 



Bi-acromial breadth. This measurement, labeled "width shoulders" in chart 

 J, should be made between lines drawn on the skin perpendicularly above the ends 

 of the acromial processes. Usually it is made after pressing down the skin over 

 the ends of these processes and there is thus introduced a highly variable factor 

 which increases the diameter from 1 per cent upwards. Weissenberg (table D) and 

 Quetelet (table E) give data on this measurement from birth to maturity. Data 

 for more limited periods are given by Landsberger (1888), Hall (1896), and Godin 

 (1910). The curves in chart J follow closely Weissenberg's data except for infancy. 

 The relative bi-acromial width for the new-born appears to be nearer 24 per cent of 

 the stature than the 21 per cent given by Weissenberg. Quetelet gives 24.5 per 

 cent and shows a decline in relative width from infancy instead of the increase 

 in width in early childhood preceding the decline, described by Weissenberg. 

 Quetelet's data in general show somewhat higher values for the relative bi-acromial 

 width than those of Weissenberg, as also do those of Godin, Hall, and Landsberger, 

 and American college statistics. In part at least, as mentioned above, this greater 

 relative width may be ascribed to technique of measurement. Weissenberg's data 

 show no clearly defined sexual differences. Quetelet gives smaller relative bi-acro- 

 mial widths for the older girls and adult women than for men of the same stature. 

 Godin 's data show a difference of 3 per cent of the stature between the bi-acromial 

 and bi-humeral width of the shoulders in the adult and 2.2 per cent at 13.5 years. 

 American college statistics of width of shoulders measured over the deltoid muscles, 

 table L, show this width in the men to be about 3 per cent of the stature greater 

 than in women, greater in short than in tall individuals and in mature than in young 

 individuals of full stature. 



Breadth of chest. The curve given in chart J and the associated data in table 

 K are based primarily on the data of Hastings (table F) . The data of Godin and of 

 Ernst correspond fairly closely. This width is considerably increased after full 

 stature is approximately attained. Godin (1910) shows an increase from 15.7 per 

 cent of the stature to 16.3 per cent from the eighteenth to the twenty-fourth year. 

 Quetelet's biaxillary diameter (table E) gives somewhat larger values except in 

 infancy. Zeising's data (1858) for width of chest in infancy, 21.6 per cent of the 

 stature, correspond with such observations as I have made. Sexual differences are 

 uncertain. Hastings in general gives a greater relative width of chest for boys, 

 Ernst for girls. The latter are exceptionally wide-chested. 



Depth of chest. Hastings^ (table F) gives data which show a depth of chest 

 slightly smaller than that shown by similar data of Quetelet (1870), Hall (1896), and 

 Ernst (1906). Ernst states that her data confirm those of Sack and Hrdlicka in 

 showing a more rapid growth in the transverse than in the antero-posterior diameter 

 of the chest during childhood. She also finds boys relatively thicker-chested than 

 girls. Godin (1903) shows a slight increase in the thoracic index between 13.5 and 

 17.5 years of age in boys. 



Depth of abdomen. This measurement is one of the most important from the 

 standpoint of relative build since it gives us the best index of relative adiposity in 

 individuals with otherwise normal abdominal structure. Unfortunately there are 



