Ill] 



OF PARTS OR ORGANS 



The Length of the Head in Man at various Ages. 

 {After Quetelet, f. 207.) 



Men Women 



93 



* A smooth curve, very similar to this, for the growth in "auricular height" 

 of the girl's head, is given by Pearson, in Biometrika, iii, p. 141, 1904. 



As regards external form, very similar differences exist, which 

 however we must express in terms not of weight but of length. 

 Thus the annexed table shews the changing ratios of the vertical 

 length of the head to the entire stature ; and while this ratio 

 constantly diminishes, it will be seen that the rate of change is 

 greatest (or the coefficient of acceleration highest) between the 

 ages of about two and five years. 



In one of Quetelet's tables {supra, p. 63), he gives measure- 

 ments of the total span of the outstretched arms in man, from 

 year to year, compared with the vertical stature. The two 

 measurements are so nearly identical in actual magnitude that a 

 direct comparison by means of curves becomes unsatisfactory; 

 but I have reduced Quetelet's data to percentages, and it will be 

 seen from Fig. 19 that the percentage proportion of span to 

 height undergoes a remarkable and steady change from birth to 

 the age of twenty years ; the man grows more rapidly in stretch 

 of arms than he does in height, and the span which was less than 



xm, pp. &-17, 1903. Warneke, P., Mitteilimg neuer Gehirn imd Korperge- 

 wichtsbestimmungen bei Saugern, neb.st Zusammenstellung der gesammten bisher 

 beobachteten absoluten imd relativen Gehirngewichte bei den verschiedenen 

 Species, J. f. Psychol, u. Neurol, xm, pp. 355—403, 1909. Donaldson, H. H., On 

 ' the regular seasonal Changes in the relative Weight of the Central Nervous System 

 of'the Leopard Frog, Journ. of Morph. xxii, pp. 663-694, 1911. 



