K. Pearson 
149 
the same scale. We thus obtain the six points of Diagram XII., all well within 
the limits of random sampling, lying on the straight line found from the fourfold 
division of the data. The slope of this line is '47 or 47, close to 50, in the 100. 
There can, I think, be small doubt that Intelligence or Ability follows precisely 
the same laws of inheritance as General Health, and both the same laws as 
Cephalic Index, or any other physical character. 
In precisely the manner indicated here all the other physical and psychical 
characters recorded may be dealt with. But before we sum up our results for the 
slopes of all the lines thus investigated, it is most essential to make, especially to 
an anthropological audience, some remarks on the manner in which the individual 
physical and mental characters have been treated. 
(iii) Rema?'ks on Individual Characters dealt with. 
Physical Characters. 
(A) Health. — We have already seen how this was recorded. In order to 
deduce the correlation two fourfold tables were made. In the one the division was 
made between Delicate and Normally Healthy, in the other between Normally 
Healthy and Strong. Theoretically the fourfold divisions ought to be made every- 
where where possible, and the weighted mean taken of the results to smooth out 
irregularities, but the labour is too great for practical purposes, and we must 
content ourselves with a few simple divisions. 
(B) Hye Colour. — Our division was into light, medium, dark. The eyes 
corresponding to these classes are stated in the general instructions. See 
Appendix Ia. For practical purposes the scale is one of the intensity of 
yellow pigmentation *. In this case, remembering that " medium " is rather 
a vague class, the fourfold division was taken at each of the four corners of 
the medium-medium category and the mean correlation of the four resulting tables 
taken to represent the actual correlation in eye colour. 
(C) Hair Colour. — This is a character concerning which we sadly need a 
combined investigation on the part of a physiologist, a chemist, and an anthropologist. 
In saying this, I am not forgetting the pioneer work of Mr H. C. Sorby published 
in the Journal of this Institute-f-. I do not feel perfectly convinced that we have 
really got to the number of pigments involved. Even if we have, and there be just 
two, it by no means follows that our nomenclature enables us effectually to separate 
hair possessing these pigments in various degrees, still less to place in their right 
position in any scale the cases of blended pigments. Assume by way of illustration 
* Blue is to be considered as an absence of pigmentation, 
t Jour. Anthr. Inst., Vol. viii. 1878, pp. 1—14. 
