XIV COLOURS OF MAMMALS 289 



dark races of mankind owe the colour of their skin 

 to a black pigment deposited in the deeper layers of 

 the epidermis — a pigment which is practically absent 

 in white-skinned people. The varying tints of the 

 hair are also due to the varying amounts of the same 

 dark pigment deposited in it. That differences in 

 skin-colour often correspond to profound racial dif- 

 ferences is familiar in a rough way to every one, but 

 there are some interesting facts which tend to show 

 that even apparently slight differences in intensity of 

 pigmentation may correspond to relatively vast con- 

 stitutional differences. 



We propose to confine our study of the question 

 to variations in the colour of the hair and eyes in 

 the white-skinned peoples, where the data are most 

 easily obtainable. The first point of interest is the 

 curious fact shown by Galton's statistical researches 

 that among ourselves there is little tendency for the 

 dark and fair strains to mingle, " to be swamped by 

 intercrossing," in the current phrase. The children 

 of parents of whom one is dark and the other fair 

 will as a rule either have dark or light eyes, only 

 rarely will they have eyes of medium colour {Natural 

 Inheritance, p. 139). In Mr. Bateson's words, the 

 variations are discontinuous. 



The next point is that, according to Dr. Beddoe's 

 prolonged observations, " the colour of the hair is so 

 nearly permanent in races of men as to be fairly trust- 

 worthy evidence in the matter of ethnical descent, and 

 nearly as much may be said for the colour of the iris " 

 {The Races of Britain, p. 269). His observations 

 further show that the dark-haired people correspond 

 roughly to the Gaelic and Iberian stocks, while the fair- 



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