within a very narrow geographical range this primitive and unmixed race presents very great differences of cranial form.[169] Exclusive of idiots, artificially compressed heads, and deformities, the differences between the brachy-kephalic and dolicho-kephalic heads range from equality in the parietal and longitudinal diameter to the proportion of about 14 to 24. As stated by some ethnologists, these differences appear quite characteristic and distinct; but, so soon as we attempt any minute discrimination, all confidence in them as specific characters disappears. In our ordinary European races similar differences, and nearly as extensive, occur. The dolicho-kephalic head is really only an immature form perpetuated; and appears not only in the Negro, but in the Esquimau, and in certain ancient and modern Celtic races. The brachy-kephalic head, in like manner, is characteristic of certain tribes and portions of tribes of Americans, but not of all; of many northern Asiatic nations; of certain Celtic and Scandinavian tribes; and often appears in the modern European races as an occasional character. Farther, as Retzius has well shown, the long heads and prominent jaws are not always associated with each other; and his classification is really the testimony of an able observer against the value of these characters. He shows that the Celtic and Germanic races (in part) have long heads and straight jaws; while the Negroes, Australians, Oceanians, Caribs, Greenlanders, etc., have long heads and prominent jaws. The Laplanders, Finns, Turks, Sclaves, Persians, etc., have short heads and straight jaws; while the Tartars, Mongolians, Incas, Malays, Papuans, etc., have short heads and prominent jaws. Another defect in the argument often based on the diverse forms of heads is its want of acknowledgment of the ascertained and popularly known fact that these forms in different tribes or individuals of the same race are markedly influenced by culture and habits of life. In all races ignorance and debasement tend to induce a prognathous form, while culture tends to the elevation of the nasal bones, to an orthognathous condition of the jaws, and to an elevation and expansion of the cranium.[170]