132 Relationship of Intelligence to Size and Shape of Head 
Slow Dull and Veri/ Dull together and calculated the corresponding percentages in 
the heavy bracketed figures*. 
Health and Intelligence. We sec that for both boys and girls we have sensibly 
homoclinal systems. The robust children among dull and slow children are much 
below the general percentage, and rise above it for the able children. Conversely the 
delicate children are below the general percentage on the intelligent side, and rise 
much above it on the dull side. There is one peculiarity which, I think, is not an 
irregularity of random sampling, but a sexual difference. Among the Quick 
Intelligent boys there is a smaller percentage of robust and a larger percentage 
of delicate than among the Intelligent boys. Thus, while abilit}' is associated with 
health, a certain number of weakly boys are markedly intelligent. With the girls, 
on the other hand, the Quick Intelligent have the largest percentage of robust 
cases. And this is, perhaps, what one would, from the standpoint of national 
efficiency, prefer — i.e. the closest association of strength and intelligence. A 
further sexual diffei'cnce is that the percentage of robust girls is smaller and the 
percentage of delicate girls is larger than in the case of boys. 
Analograph of Health and Intelligence. 
Scale of Intelligence in Mentaces. 
Pigmentation and Intelligence. Both hau- and eye colour clearly provide 
heteroclinal systems, but it is difficult to trace any nomic relationship in either 
the numbers or the graphs. 'J'hus, while brown-haired boys give a fairly smooth 
homoclinal graph, showing decreasing percentages with increasing intelligence, 
there is no corresponding feature in brown-haired girls, the deviation from the 
The following are sufficiently closely for practical purposes the mean values of each intellectual 
grade : 
Mentally Defective - 317 mentaces. 
Very Dull -238 
Slow Dull - 170 
Slow - 108 
Slow Intelligent - 38 ,, 
Fair Intelligence -t- 22 mentaces. 
Capable +71 ,, 
Specially Able +1.j1 ,, 
Genius +317 ,, 
