Hecke, W. “Volksvermehrung, Binnenwanderung, und Umgangssprache in den österreichischen Alpenländern und Südländern,” _Statist. Monatsschr._, XXXIX (1913), 323–92. (VIII, 1. 3; X, 2.) Hoaglund, H. E. “The Movement of Rural Population in Illinois,” _Jour. Pol. Econ._, XX (1912), 913–27. Mayr, G. von. _Die Bevölkerung der Grossstädte_, in “Die Grossstadt” (Dresden, 1903). One of the best statements of the problem. (VII, 1, 2; VIII, 1, 2, 3.) Prinzing, Dr. F. “Die Bevölkerungsentwicklung Stockholms, 1721–1920,” _Jahrbuch für Nationalökonomie und Statistik_, XLVII (1924), 87–93. An excellent case study of the situation in a modern European city. (VII, 1; X, 1, 2.) ——. “Einheimische und Zugezogene in den Grossstädten,” _Zeitschr. für Sozialwiss._, VII (Berlin, 1904), 660–67. Ravenstein, E. G. “The Laws of Migration,” _Jour. Royal Statist. Soc._, XLVIII (1885), 167–227. (X, 2.) Spencer, A. G. “Changing Population of Our Large Cities,” _Kindergarten Primary Mag._, XXIII (1910), 65–71. Steinhart, A. _Untersuchung zur Gebürtigkeit der deutschen Grossstadtbevölkerung, Entwicklung, und Ursachen_, “Rechts und Staatswissenschaftliche Studien,” Heft 45 (Berlin, 1912). (VIII, 1; X, 2.) Voss, W. “Städtische Kleinsiedlung,” _Archiv für exacte Wirtschaftsforschung_, IX (1919), 377–412. Weisstein, G. “Sind die Städte wirklich Menschenverzehrer?” _Deutsche Städte Ztg._ (1905), pp. 153–54. 4. The mobility of a city population incident to city growth is reflected in the increased number of contacts, changes of movement, changes in appearance, and atmosphere of specific areas due to succession of population groups, and in differences in land values. Mobility implies not mere movement, but fresh stimulation, an increase in number and intensity of stimulants, and a tendency to respond more readily to new stimulation. The process by which the city absorbs and incorporates its own offspring or foreign elements into its life, and what becomes of them, may be referred to as the metabolism of city life. Mobility is an index of metabolism. Bercovici, Konrad. _Around the World in New York_ (New York, 1924). Discusses the local communities and the sifting process in the large city. (VII, 1, 2; IX, 3; V, 1, 2, 3.) Digby, E. “The Extinction of the Londoner,” _Contemp. Rev._, London, XXCVI (1904), 115–26. (VII, 2, 3; VIII, 1; IX, 2, 3.) Herzfeld, Elsa G. _Family Monographs; The History of Twenty-four Families Living in the Middle West Side of New York City_ (New York, 1905). Examples of extreme mobility (tendency to migrate) in the tenement district. (VII, 5.) Meuriot, P. “Les Migrations internes dans quelques grandes villes,” _Jour. Soc. Stat._, Paris, L (1909), 390. (V, 1; VII, 2.)