Porter — The Physical Basis of Precocity and Duliness. 179 
mean weights of the whole mass of observations at each age, 
irrespective of school grade. 
TABLE NO. 17. 
The Mean of = Weights of Boys of Mean Precocity and Duliness compared 
ith the Mean Weight irrespective of School Gr 
Mean Mean Mean irrespective 
Age. Precocity. Dullness. Mean. of School Grades, 
7++++--48,64 Ibs, 46.69 lbs. 47.66 lbs. 47.73 lbs. 
Be 20 - - BS.50 51.59 52.54 52.58 
ae 58.64 56.12 57.38 57.75 
af rar 64.05 60.95 62.50 62.48 
U1 «ss. 69.57 66.96 68.26 68.47 
12. 00060 75.24 72.26 73.75 73.61 
13....--+81.00 77.36 79.18 79.85 
14.....-90.57 85.69 88.13 88.08 
ere 5.27 94.78 100.02 100.20 
16..50% 120.96 105.00 112.98 114.17 
TABLE NO. 18. 
The Mean of the Weights of Giris of Mean Precrocity and Duliness compared 
with the Mean Weight irrespective of School Grade. 
Mean Mean Mean irrespective 
Age. Precocity. Duillness. Mean, of School Grades. 
Teeees+ 46.96 lbs. 44,68 lbs. 45.82 Ibs. 45.84 lbs 
4 oe boas bbO 49,52 50.36 50.35 
eere. 56.25 54.32 55.28 55.17 
.% ooo ee G1.34 59.44 60.39 60.46 
Deve. 86:75 64.84 65.78 65.64 
ce pereee ee TL.72 73.15 73.23 
1B. 2 0086.48 80.39 83.41 83.735 
14. oe 96.61 92.00 94.30 93.94 
15.....104.54 100.03 102.28 103.20 
16.06. -EES/31 108.39 110.85 110.06 
The coincidence in the two series is noticeable. 
The three pairs of curves in Plate II may now be examined 
in detail. The three full lines of boys’ weights run courses 
not strictly parallel. A slight divergence of the curves of 
the dull and the precocious is evident in the case of the older 
boys. This would seem to indicate that the difference in 
weight between dull and precocious boys increases as they 
grow older. It would further seem to show that this increas- 
ing divergence is associated chiefly with the acceleration of 
