(4) Spencer, Herbert. "The Social Organism," _Essays, Scientific, Political and Speculative_. I, 265-307. New York, 1892. [First published in _The Westminster Review_ for January, 1860.] (5) Lazarus, M., and Steinthal, H. "Einleitende Gedanken zur Völkerpsychologie als Einladung zu einer Zeitschrift für Völkerpsychologie und Sprachwissenschaft," _Zeitschrift für Völkerpsychologie und Sprachwissenschaft_, I (1860), 1-73. [This is the most important early attempt to interpret social phenomena from a social psychological point of view. See p. 35 for definition of _Volk_ "the people."] (6) Knapp, G. Friedrich. "Quételet als Theoretiker," _Jahrbücher für Nationalökonomie und Statistik_, XVIII (1872), 89-124. (7) Lazarus, M. _Das Leben der Seele in Monographien über seine Erscheinungen und Gesetze._ Berlin, 1876. (8) Durkheim, Émile. "Représentations individuelles et représentations collectives," _Revue de métaphysique et de morale_, VI (1898), 273-302. (9) Simmel, Georg. _Über sociale Differenzierung._ Sociologische und psychologische Untersuchungen. Leipzig, 1890. [See also in Bibliography, chap. i, volumes listed under Systematic Treatises.] II. PLANT COMMUNITIES AND ANIMAL SOCIETIES (1) Clements, Frederic E. _Plant Succession._ An analysis of the development of vegetation. Carnegie Institution of Washington, 1916. (2) Wheeler, W. M. "The Ant-Colony as an Organism," _Journal of Morphology_, XXII (1911), 307-25. (3) Parmelee, Maurice. _The Science of Human Behavior._ Biological and Psychological Foundations. New York, 1913. [Bibliography.] (4) Massart, J., and Vandervelde, É. _Parasitism, Organic and Social._ 2d ed. Translated by W. Macdonald. Revised by J. Arthur Thomson. London, 1907. (5) Warming, Eug. _Oecology of Plants._ An introduction to the study of plant communities. Oxford, 1909. [Bibliography.] (6) Adams, Charles C. _Guide to the Study of Animal Ecology._ New York, 1913. [Bibliography.] (7) Waxweiler, E. "Esquisse d'une sociologie," _Travaux de l'Institut de Sociologie (Solvay), Notes et mémoires_, Fasc. 2. Bruxelles, 1906. (8) Reinheimer, H. _Symbiosis._ A socio-physiological study of evolution. London, 1920. III. THE CLASSIFICATION OF SOCIAL GROUPS A. _Types of Social Group_ 1. Non-territorial Groups: (1) Le Bon, Gustave. _The Crowd._ A study of the popular mind. London, 1897. (2) Sighele, S. _Psychologie des sectes._ Paris, 1898. (3) Tarde, G. _L'opinion et la foule._ Paris, 1901. (4) Fahlbeck, Pontus. _Klasserna och Samhallet._ Stockholm, 1920. (Book review in _American Journal of Sociology_, XXVI [1920-21], 633-34.) (5) Nesfield, John C. _Brief View of the Caste System of the North-western Provinces and Oudh_. Allahabad, 1885. 2. Territorial Groups: (1) Simmel, Georg. "Die Grossstädte und das Geistesleben," _Die Grossstadt_, Vorträge und Aufsätze zur Städteausstellung, von K. Bücher, F. Ratzel, G. v. Mayr, H. Waentig, G. Simmel, Th. Peterman, und D. Schäfer. Dresden, 1903.