Fig. 4. Mean annual increments of stature (
), Belgian and American.
and very marked acceleration of growth beginning at about twelve years of age, and lasting for three or four years; when this period of acceleration is over, the rate begins to fall again, and does so with great rapidity. We do not know how far the absence of this striking feature in the Belgian curve is due to the imperfections of Quetelet’s data, or whether it is a real and significant feature in the small-statured race which he investigated.
| Belgian (Quetelet, p. 344) | Paris* (Variot et Chaumet, p. 55) | Toronto† (Boas, p. 1547) | Worcester‡, Mass. (Boas, p. 1548) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Age | Height (Boys) | Ann. increment | Height | Increment | Height (Boys) | Variability of do. (6) | Ann. increment | Ann. increment (Boys) | Variability of do. | Ann. increment (Girls) | Variability of do. | ||
| Boys | Girls | Boys | Girls | ||||||||||
| 0 | 50·0 | — | — | — | — | — | — | — | — | — | — | — | — |
| 1 | 69·8 | 19·8 | 74·2 | 73·6 | — | — | — | — | — | — | — | — | — |
| 2 | 79·1 | 9·3 | 82·7 | 81·8 | 8·5 | 8·2 | — | — | — | — | — | — | — |
| 3 | 86·4 | 7·3 | 89·1 | 88·4 | 6·4 | 6·6 | — | — | — | — | — | — | — |
| 4 | 92·7 | 6·3 | 96·8 | 95·8 | 7·7 | 7·4 | — | — | — | — | — | — | — |
| 5 | 98·7 | 6·0 | 103·3 | 101·9 | 6·5 | 6·1 | 105·90 | 4·40 | — | — | — | — | — |
| 6 | 104·0 | 5·9 | 109·9 | 108·9 | 6·6 | 7·0 | 111·58 | 4·62 | 5·68 | 6·55 | 1·57 | 5·75 | 0·88 |
| 7 | 110·4 | 5·8 | 114·4 | 113·8 | 4·5 | 4·9 | 116·83 | 4·93 | 5·25 | 5·70 | 0·68 | 5·90 | 0·98 |
| 8 | 116·2 | 5·8 | 119·7 | 119·5 | 5·3 | 5·7 | 122·04 | 5·34 | 5·21 | 5·37 | 0·86 | 5·70 | 1·10 |
| 9 | 121·8 | 5·6 | 125·0 | 124·7 | 5·3 | 4·8 | 126·91 | 5·49 | 4·87 | 4·89 | 0·96 | 5·50 | 0·97 |
| 10 | 127·3 | 5·5 | 130·3 | 129·5 | 5·3 | 5·2 | 131·78 | 5·75 | 4·87 | 5·10 | 1·03 | 5·97 | 1·23 |
| 11 | 132·5 | 5·2 | 133·6 | 134·4 | 3·3 | 4·9 | 136·20 | 6·19 | 4·42 | 5·02 | 0·88 | 6·17 | 1·85 |
| 12 | 137·5 | 5·0 | 137·6 | 141·5 | 4·0 | 7·1 | 140·74 | 6·66 | 4·54 | 4·99 | 1·26 | 6·98 | 1·89 |
| 13 | 142·3 | 4·8 | 145·1 | 148·6 | 7·5 | 7·1 | 146·00 | 7·54 | 5·26 | 5·91 | 1·86 | 6·71 | 2·06 |
| 14 | 146·9 | 4·6 | 153·8 | 152·9 | 8·7 | 4·3 | 152·39 | 8·49 | 6·39 | 7·88 | 2·39 | 5·44 | 2·89 |
| 15 | 151·3 | 4·4 | 159·6 | 154·2 | 5·8 | 1·3 | 159·72 | 8·78 | 7·33 | 6·23 | 2·91 | 5·34 | 2·71 |
| 16 | 155·4 | 4·1 | — | — | — | — | 164·90 | 7·73 | 5·18 | 5·64 | 3·46 | — | — |
| 17 | 159·4 | 4·0 | — | — | — | — | 168·91 | 7·22 | 4·01 | — | — | — | — |
| 18 | 163·0 | 3·6 | — | — | — | — | 171·07 | 6·74 | 2·16 | — | — | — | — |
| 19 | 165·5 | 2·5 | — | — | — | — | — | — | — | — | — | — | — |
| 20 | 167·0 | 1·5 | — | — | — | — | — | — | — | — | — | — | — |
* Ages from 1–2, 2–3, etc.
† The epochs are, in this table, 5·5, 6·5, years, etc.
‡ Direct observations on actual, or individualised, increase of stature from year to year: between the ages of 5–6, 6–7, etc.
Even apart from these data of Quetelet’s (which seem to constitute an extreme case), it is evident that there are very {68} marked differences between different races, as we shall presently see there are between the two sexes, in regard to the epochs of acceleration of growth, in other words, in the “phase” of the curve.