33 : 23–34: 21. Haddon, 1, pp. 2 and 3, and Deniker, 2, pp. 42 _seq._ While this classification is substantially sound, and sufficient for our purpose, recent investigations have shown that other factors also contribute to straightness or kinkiness, such as coarseness of texture, as opposed to fineness. Probably these will be determined by Mr. Louis R. Sullivan, of the American Museum of Natural History, who is working on the subject. It has been found that the Japanese and Eskimo are exceptions to the rule of “straight hair, round cross section,” for they show an ellipse. There is also a wide range of variation in the cross-sections of hair for individuals of any race, who are classified according to the preponderance of cross-sections of a single type. For a fine series of plates which are photographs of the magnified hair of individuals of various races, see _Das Haupthaar und seiner Bildungsstatte bei den Rassen des Menschen_, Gustave Fritsch. Another recent paper is the study by Leon Augustus Hausmann of Cornell, “The Microscopic Structure of the Hair as an Aid in Race Determination.” 35 : 27. Livi, _Antropometria Militare_, and Ripley, pp. 115, 255 and 258. 36. Deniker, 1; Zampa, 1,2; Weisbach, 1, 2, 3; and others given by Ripley, pp. 411–415. CHAPTER III. RACE AND HABITAT 37 : 6. Sir G. Archdall Reid, _The Principles of Heredity_, chaps. VII, VIII, IX. 37 : 17. Ripley discusses them in full in chap. VI. 37 : 20–38 : 2. W. Boyd Dawkins, _Early Man in Britain_, p. 233; Keane, _Ethnology_, pp. 110 _seq._; Osborn, _Men of the Old Stone Age_, pp. 220, 479–486 _seq._; Keith, _Antiquity of Man_, p. 16. 38 : 10. Ellsworth Huntington, 1, p. 83; Charles E. Woodruff, 1, pp. 85–86; also the Report of the Smithsonian Institution for 1891, which contains an article on “Isothermal Zones.” 38 : 17 _seq._ Ellsworth Huntington, 1, pp. 86 _seq._ 40 : 27. Ellsworth Huntington, 1, pp. 14, 27. 41 : 25–42. G. Retzius, _On the So-called North European Race of Mankind_, p. 300; and many other authorities. 43 : 23. Ripley, pp. 352 _seq._ and 470. 44 : 17. G. Elliot Smith, 1, p. 61; G. Sergi, 4. 44 : 26. Ripley, pp. 443 and 582–583. 45 : 2. Beddoe, 4, p. 270. CHAPTER IV. THE COMPETITION OF RACES 47 : 17. Prescott F. Hall, _Immigration Restriction and World Eugenics_. 49 : 15–51. See the _Eugenics Record Office Bulletins_, 10A and 10B, by Harry H. Laughlin, Cold Spring Harbor, Long Island. Part I is “The Scope of the Committee’s Work”; Part II, “The Legal, Legislative and Administrative Aspects of Sterilization.” See also H. H. Hart, _Sterilization as a Practical Measure_; and Raymond Pearl, _The Sterilization of Degenerates_; as well as _The Eugenical News_ for April, May and August, 1918. 52 : 17. Sir Francis Galton, _Hereditary Genius_, pp. 351–359; Darwin, _The Descent of Man_, p. 218. 53 : 6. Galton, _Hereditary Genius_, pp. 345–346.