VARIATION IN THE MELANIN CONTENT OF THE SKIN OF NEW GUINEA NATIVES AT DIFFERENT AGES

[摘要] A survey has been made of the melanin pigment of the forehead, forearm and axilla of New Guinea natives of varying ages. The reflectance of light with a maximum transmission of 650 mu was measured with a photovoltaic cell and microammeter and the value expressed relative to the reflectance from a magnesium oxide surface as 100%. The forehead contains more melanin than the forearm and axilla at all ages and this is probably related to the melanocyte content of the skin in different areas. The exposed areas of adult skin show increasing pigmentation with increasing age, especially in males, but the melanin content of the axilla shows little change. The newborn infant has relatively little melanin except in the sacral and scrotal skin, but rapidly acquires pigment so that by 6 months of age the forehead, forearm and axilla are as dark as in the young adult.