[41] F.A. Forel, _Handbuch der Seenkunde: allgemeine Limnologie_ (Stuttgart, 1901); F.A. Forel, "La Limnologie, branche de la geographie," _Report VI. Int. Geog. Congress_ (London, 1895), p. 593; also _Le Leman_ (2 vols., Lausanne, 1892, 1894); H. Lullies, "Studien uber Seen," _Jubilaumsschrift der Albertus-Universitat_ (Konigsberg, 1894); and G.R. Credner, "Die Reliktenseen," _Petermanns Mitteilungen_, Erganzungshefte 86 and 89 (Gotha., 1887, 1888). [42] J. Murray, "Drainage Areas of the Continents," _Scot. Geog. Mag._ ii. (1886) p. 548. [43] Wagner, _Lehrbuch der Geographie_ (1900), i. 586. [44] For details, see A.R. Wallace, _Geographical Distribution of Animals and Island Life_; A. Heilprin, _Geographical and Geological Distribution of Animals_ (1887); O. Drude, _Handbuch der Pflanzengeographie_; A. Engler, _Entwickelungsgeschichte der Pflanzenwelt_; also Beddard, _Zoogeography_ (Cambridge, 1895); and Sclater, _The Geography of Mammals_ (London, 1899). [45] See particularly A. de Lapparent, _Traite de geologie_ (4th ed., Paris, 1900). [46] Estimate for 1900. H. Wagner, _Lehrbuch der Geographie_, i. P. 658. [47] Estimate for year not stated. A.H. Keane in _International Geography_, p. 108. [48] In _Proc. R. G. S._ xiii. (1891) p. 27. [49] On the influence of land on people see Shaler, _Nature and Man in America_ (New York and London, 1892); and Ellen C. Semple's _American History and its Geographic Conditions_ (Boston, 1903). [50] See maps of density of population in Bartholomew's great large-scale atlases, _Atlas of Scotland_ and _Atlas of England_. [51] For the history of territorial changes in Europe, see Freeman, _Historical Geography of Europe_, edited by Bury (Oxford), 1903; and for the official definition of existing boundaries, see Hertslet, _The Map of Europe by Treaty_ (4 vols., London, 1875, 1891); _The Map of Africa by Treaty_ (3 vols., London, 1896). Also Lord Curzon's Oxford address on _Frontiers_ (1907). [52] For numerous special instances of the determining causes of town sites, see G.G. Chisholm, "On the Distribution of Towns and Villages in England," _Geographical Journal_ (1897), ix. 76, x. 511. [53] The whole subject of anthropogeography is treated in a masterly way by F. Ratzel in his _Anthropogeographie_ (Stuttgart, vol. i. 2nd ed., 1899, vol. ii. 1891), and in his _Politische Geographie_ (Leipzig, 1897). The special question of the reaction of man on his environment is handled by G.P. Marsh in _Man and Nature, or Physical Geography as modified by Human Action_ (London, 1864). [54] For commercial geography see G.G. Chisholm, _Manual of Commercial Geography_ (1890).