[183] The introduction of the rabbit into Australia, where predatory competitors are absent, has resulted in so great a multiplication of the members of this species that their numbers have become an economic menace. The appearance of the boll weevil, an insect which attacks the cotton boll, has materially changed the character of agriculture in areas of cotton culture in the South. Scientists are now looking for some insect enemy of the boll weevil that will restore the equilibrium.
[184] Adapted from J. Arthur Thomson, Darwinism and Human Life, pp. 72-75. (Henry Holt & Co., 1910.)
[185] Adapted from Charles Darwin, The Origin of Species, pp. 50-61. (D. Appleton & Co., 1878.)
[186] Adapted from Charles Darwin, The Origin of Species, pp. 97-100. (D. Appleton & Co., 1878.)
[187] Adapted from George W. Crile, Man: An Adaptive Mechanism, pp. 17-39. (Published by The Macmillan Co., 1916. Reprinted by permission.)
[188] Adapted from F. E. Clements, Plant Succession. An analysis of the development of vegetation, pp. 75-79. (Carnegie Institution of Washington, 1916.)
[189] Adapted from Carl Bücher, Industrial Evolution, pp. 345-69. (Henry Holt & Co., 1907.)
[190] From William Z. Ripley, The Races of Europe, pp. 537-59. (D. Appleton & Co., 1899.)
[191] Adapted from Francis A. Walker, Economics and Statistics, II, 421-26. (Henry Holt & Co., 1899.)
[192] Adapted from John B. Clark, "The Limits of Competition," in Clark and Giddings, The Modern Distributive Process, pp. 2-8. (Ginn & Co., 1888.)