536 HEIGHT AND WEIGHT IN RELATION TO BUILD 



puberty, but during adolescence diverge again and continue to diverge during 

 maturity. The region of divergence centers at the height of full stature. The 

 region of divergence in a group of short individuals is lower than that shown in the 

 charts. The region of divergence in a group of tall individuals is higher and less 

 marked. The girths show the same characteristics as the transverse diameters but 

 to a greater degree. The girth of the head, however, shows little evidence of diver- 

 gence at full stature. Pfitzner (1899) describes a continued increase in relative 

 head-girth up to old age. 



When using the metric-system units the simplest method of estimating average 

 transverse section and average transverse diameter ratios is to use the metric height- 

 weight index of build for the former and its square root for the latter. Since the 

 metric height-weight index in reference to volume assumes a specific gravity of 1000 

 for a gram of tissue the ratio of cross-section to square of the stature thus estimated 

 is approximately 2.5 per cent larger than when a specific gravity of 1.0252 is assumed, 

 as we have in dealing with pounds and inches. The ratio of the average transverse 

 diameter to stature is correspondingly increased 1.24 per cent. In comparison with 

 the indices based on the inch-pound index of build, the metric transverse section 

 ratio is 0.2768 as great, the transverse diameter index is V0.2768 or 0.526 as 

 great. The latter index is therefore approximately one-half as large as that based 

 on the inch-pound height-weight index. 



In table L we have estimated this centimeter-gram average transverse diameter 

 ratio for each of the groups of individuals studied in order to facilitate a comparison 

 between the ratios which it expresses and ratios of linear measurements to stature. 



From Hitchcock (1900) we have data on college students graded according 

 to stature. The proportions for three such groups (a) 160 cm., (b) 175 cm. and 

 (c) 183 cm. are given in table L. The average transverse diameter ratio of group 

 (a) is 0.11472, of group (b) 0.10949, of group (c) 0.10559. There is thus a pro- 

 gressive decrease in average relative transverse diameter from the shortest to the 

 tallest. In the tallest it is 7.95 per cent less than in the shortest. 



Of the relative heights, the only one to show a progressive change in the same 

 direction is sitting-height, which is 3.75 per cent less in group (c) than in group (a). 

 The other heights, especially the height of the knee, show an increase. On the 

 other hand the breadths of the head, neck, shoulders, and hips measured at the 

 trochanters show a decrease of somewhat the same order of magnitude as the 

 average transverse diameter. The width of the head shows the greatest decrease, 

 that of the hips the least. Similar differences may be seen in the relative girths. 

 The girth of the head here also shows the greatest decrease, but the decrease in 

 girth of the hips at the trochanters is larger than that in breadth of hips and 

 is of the same order of magnitude as that of the average transverse diameter. 

 Anne L. Barr (Clapp) (1903) has furnished similar data for Nebraska college girls. 

 Relative measurements of groups of stature (a) 150 cm., (6) 160 cm., and (c) 173 cm. 

 are given in table L. Here also we find a decrease in relative average transverse 

 diameter from 0.11662 in group (a) to 0.10719 in group (c), or 8.09 per cent. Sitting- 

 height, breadths, and depths likewise show a decrease, but the girths (with the 

 exception of those of the head, neck, and chest) are either essentially similar in the 



