viii.] DISCUSSION OF THE DATA OF EYE COLOUR. 141 



fear that some cases of young children have been acci- 

 dentally included. I would willingly have taken a later 

 limit than eight years, but could not spare the data 

 that would in that case have been lost to me. 



A great variety of terms are used by the various 

 compilers of the "Family Records" to express Eye- 

 colours. I began by classifying them under the follow- 

 ing eight heads ; — 1, light blue ; 2, blue, dark blue ; 

 3, grey, blue-green ; 4, dark grey, hazel ; 5, light brown ; 

 6, brown ; 7, dark brown ; 8, black. Then I constructed 

 Table 15. 



The diagram, page 143, clearly conveys the signifi- 

 cance of the figures in Table 15. Considering that 

 the groups into which the observations are divided are 

 eight in number, the observations are far from being 

 sufficiently numerous to justify us in expecting clean 

 results ; nevertheless the curves come out surprisingly 

 well, and in accordance with one another. There can 

 be little doubt that the change, if any, during four 

 successive generations is very small, and much smaller 

 than mere memory is competent to take note of. I 

 therefore disregard a current popular belief in the exist- 

 ence of a gradual darkening of the British population, 

 and shall treat the eye-colours of those classes of 

 our race who have contributed the records, as having 

 been statistically persistent during the period under 

 discussion. 



The concurrence of the four curves for the four 

 several generations, affords internal evidence of the 

 trustworthiness of the data. For supposing we had 



