l6 THE RELATIVE STRENGTH OF 



of the mother and height of her sons in Glasgow. 

 In Glasgow the values found range from -i to '2. 

 At present I have no final explanation beyond 

 heterogeneity for this result. But I would mention 

 a fact noted by Mr Tocher in a paper on a pig- 

 mentation survey of Scotland, published recently in 

 Biometrika. In that paper Mr Tocher calls atten- 

 tion to the large foreign element in Glasgow as 

 judged by the names of the children and confirmed 

 by their hair and eye-colour. There are a large 

 number of Jews, especially in Groups B and C, 

 and a fairly large proportion of Irish in the schools 

 in Group D. Can mixture of races account for the 

 higher correlations in some of the Glasgow groups^? 

 Future investigations will show whether the in- 

 fluence of the mother's employment on the height of 

 her sons is greater than (as apparently in Glasgow) 

 or less than (as apparently in Edinburgh) the in- 

 fluence of her employment on the weight, and 

 whether the influence of employment on height is 

 represented by the higher or lower correlation 

 coefficient, by '2 or by 'i. At present I must con- 

 tent myself with saying that the connection between 

 the employment of the mother and the weight of 

 her sons is about '12, and that the connection 

 between the employment of the mother and the 

 height of her sons Is between 'i and '2. Taking 

 into consideration the result found in the worst school 



^ If we compare the mean height and weight of the Edinburgh 

 boys with those of boys in the different school groups at Glasgow, we 

 find that they lie between the Glasgow groups A and B, just where 

 the correlation coefficients fall. Thus the Edinburgh and Glasgow 

 values may not be really contradictory. 



