VIII.] DISCUSSION OF THE DATA OF EYE COLOUR. 141
fear that some cases of young children have been accidentally 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 Eyecolours. I began by classifying them under the following 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 significance 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 existence 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
