graphical Distribution of Fossil Plants" (1888); "Psychic Factors of Civilization"; "Psychological Basis of Social Economics"; "Political Ethics of Spencer"; "Principles of Sociology"; and "Outlines of Sociology" (1898); "Sociology and Economics" (1899); "Pure Sociology" (1903); and more than two hundred other scientific titles. He is a member of the American Economic Association; American Philosophical Society; American Academy of Political and Social Science; fellow of the American Academy for the Advancement of Science; honorary curator of botany and fossil plants, United States National Museum; member of the Cosmos club, Washington, and in 1903, was president of the Institut Internationale de Sociologie, at Paris. He received the degree of A.M. from Columbian university, in 1873, for advanced scientific work, and the honorary degree of LL.D., from the same institution in 1897.