January 6, 1893.J 



SCIENCE. 



As in the case of the two preceding diameters, the breadth of 

 face of the bojB exceeds that of the girls. But there is this slight 

 difference here; the diameters of the girls' heads approached more 

 nearly those of the boys' heads during a certain period, approxi- 

 mately, from the eleventh to the thirteenth years; but in the 

 diameter of the face the girls not only approach, but at the twelfth 

 year seem quite to reach that of the boys. 



These three curves evidence four things: first, that the time of 

 growth in the diameters of the heads and faces of girls is shorter than 

 in the case of boys; second, that up to about the twelfth year these 

 diameters grow more rapidly in girls than in boys, while after 

 that age the contrary is the case; third, that by an apparently 

 sudden rise in the annual rate of growth in the girls their diame- 



of the breadth of bead seem almost to suggest an alternation in 

 growth between the two diameters, as we shall see, the alternate 

 rising and falling of the curves of the cephalic index would seem 

 to strengthen this suggestion. 



Let us now turn to the thr^e indices, numbered on the plate 4, 

 5, and 6 and taking up as first in order the cephalic index. 



The Cephalic Index (5). — The curve of the cephalic index shows, 

 as would be expected from an examination of the component 

 curves of length of head (1) and breadth of head (3), a considera- 

 ble degree of irregularity in its annual stages. There is, never- 

 theless, a certain general regularity displayed, taking the curves 

 as a whole; both displaying three periods, composed each of a 

 decided maximum and minimum. These periods are from about 



ters approach much more nearly that of the boys during the 

 period of the eleventh, twelfth, and thirteenth years. Finally, 

 the average annual rate of growth in the diameters of the girls 

 heads and faces is nearly uniform during the two periods before 

 and after the eleventh-thirteenth years. While in the case of 

 boys it is considerably greater, actually and relati^^ely, after than 

 before. Between the fifth and the eighteenth years the length of 

 head of boys increases 16 millimeters, in the same period the 

 breadth of head increases 11 millimeters, and the width of face 

 18.5 millimeters. The corresponding measurements in the case of 

 girls increase 13 millimeters, 8 millimeters, and 17 millimeters, 

 respectively, for the same period of time. The horizontal lines 

 on the upper left hand of the diagram indicate the entire altitude 

 of the curves, the cross-bar indicating the altitude at twelve years. 

 A comparison of the annual increments of the length of head and 



the fifth to the eleventh, the eleventh to the sixteenth, and the 

 sixteenth on in girls; from the fifth to the tenth, from the tenth 

 to the thirteenth, and from the thirteenth to the eighteenth in 

 boys. The whole range of the two curves is very small, scarcely 

 two and a half per cent ; the final index being, for boys, about one 

 and one-half per cent below that of the index at five years of age; 

 the final index of the girls being very nearly the same as at five 

 years of age. The greatest altitude of the curve is, for boys, at 

 ten years, and for girls at eight years. The greatest depression 

 is at about sixteen years of age for both sexes. The cephalic in- 

 dex of girls is for the period of growth higher than that of boys, 

 except at about the ages of nine and ten. 



Breadth of Face to Breadth of Head (4).— In comparing the 

 growth of the breadth of the face to the breadth of the head, we 

 find that the breadth of face grows much more rapidly propor- 



