CHAPTER I

THE CONCEPTS OF EVOLUTION

Extension of the meaning of Darwinian concepts since Darwin--Lewes on the Struggle for Existence as internal--The mystery of "Variation" according to Darwin not a metaphysical mystery, but one of the incompleteness of scientific knowledge--Rolph's criticism of the Darwinian conception of the Struggle for Existence criticised--General classification of the theories of Evolution--Fechner's theory of the Tendency to Stability--Petzoldt on Fechner--Petzoldt's concepts of Tendency and Competition--Zöllner and Du Prel--Examination of the concept of Absolute Stability, and of a full stability of the universe, in the light of the question as to the finite or infinite character of the material universe--Periodicity in Organisms--Criticism of the concepts of Cause and Effect--Criticism of Spencer's definition of Life--The concepts of Heredity and Adaptation--The point of dispute with regard to Variation--Darwin, Haeckel, and Eimer with regard to the inheritance of individual acquirements--Criticisms of Weismann--Habit in the life of the individual--Advantage of the method pursued by Avenarius in the "Kritik der reinen Erfahrung"--Lamarck on the relation of Use and Function--Darwin on Habit and Instinct--Function and Tendency to Function--Relation of organism and environment--Theory of a special vital force--The relation of exercise to strength of Tendency--The concepts of Cause and Effect as applied to organism and environment--Relation of primary tendency to later-evolved function--Form and Function--The mixture of types in sexual propagation--Summary of conclusions 277-306