IV. MORPHOLOGICAL DEVELOPMENT.—Pointing out the relations that are everywhere traceable between organic forms and the average of the various forces to which they are subject; and seeking in the cumulative effects of such forces a theory of the forms. V. PHYSIOLOGICAL DEVELOPMENT.—The progressive differentiation of functions similarly traced; and similarly interpreted as consequent upon the exposure of different parts of organisms to different sets of conditions. VI. THE LAWS OF MULTIPLICATION.—Generalizations respecting the rates of reproduction of the various classes of plants and animals; followed by an attempt to show the dependence of these variations upon certain necessary causes.[2] THE PRINCIPLES OF PSYCHOLOGY. VOL. I. PART I. THE DATA OF PSYCHOLOGY.—Treating of the general connexions of Mind and Life and their relations to other modes of the Unknowable. II. THE INDUCTIONS OF PSYCHOLOGY.—A digest of such generalizations respecting mental phenomena as have already been empirically established. III. GENERAL SYNTHESIS.—A republication, with additional chapters, of the same part in the already-published _The Principles of Psychology_. IV. SPECIAL SYNTHESIS.—A republication, with extensive revisions and additions, of the same part, &c. &c. V. PHYSICAL SYNTHESIS.—An attempt to show the manner in which the succession of states of consciousness conforms to a certain fundamental law of nervous action that follows from the First Principles laid down at the outset. VOL. II. VI. SPECIAL ANALYSIS.—As at present published, but further elaborated by some additional chapters. VII. GENERAL ANALYSIS.—As at present published, with several explanations and additions. VIII. COROLLARIES.—Consisting in part of a number of derivative principles which form a necessary introduction to Sociology.[3] THE PRINCIPLES OF SOCIOLOGY. VOL. I. PART I. THE DATA OF SOCIOLOGY.—A statement of the several sets of factors entering into social phenomena—human ideas and feelings considered in their necessary order of evolution; surrounding natural conditions; and those ever complicating conditions to which Society itself gives origin. II. THE INDUCTIONS OF SOCIOLOGY.—General facts, structural and functional, as gathered from a survey of Societies and their changes: in other words, the empirical generalizations that are arrived at by comparing different societies, and successive phases of the same society.