PREFATORY NOTE. THE present volume is made up of popular essays or addresses on the general subject of Organic Evolution. These were originally given as oral lectures before. University Extension societies in California, having been condensed and written out in their present form after delivery. Three of these papers have already appeared in Appletons' Popular Science Monthly, and three in The Arena. To the editors of these periodicals I am indebted for the privilege of reprinting them. Besides the twelve essays of my own, it is my good fortune to enhance the value of the volume by the insertion of three papers of special importance, setting forth the present state of knowledge concerning the method of evolution and the method of heredity. The first of these, on the Factors of Organic Evolution as displayed in the Process of Development, is by Professor Edwin Grant Conklin, of the University of Pennsylvania; the second, on the Physical Basis of Heredity, is by Professor Frank Mace McFarland, of Leland Stanford Jr. University; the third, on the Testimony from Paleontology, is by Professor James Perrin Smith, of Leland Stanford Jr. University. The essay of Professor Conklin was read before the American Philosophical Society. The others are here presented for the first time. I may add that the present volume is not intended as a text-book in Evolution, although most phases of organic development are in one way or another touched upon, some of them, however, most briefly. The treatment of different topics is necessarily unequal. The time is long past when any one man can master what is known in any science, least of all the universal science of life. In the supplementary essays I have asked my scientific friends to do for this volume certain work which I could not do except by the unsatisfactory method of compilation. DAVID STARR Jordan. PALO ALTO, CALIFORNIA, January 19, 1898. ANALYSIS OF CONTENTS. I. THE KINSHIP OF LIFE. Dar- What is the cause of variety in life? What is a species ? PAGE tures in man. Gill slits in man. Objections to the the- What evolution is. The science of organic evolution or bionomics. Meaning of law. Soundness and solvency of Nature. The indifference of Nature. Evolution as a theory of organic development. Each fact has a mean- ing. Evolution as a method of study. Evolution as a system of cosmic philosophy. Decay of formulæ. What evolution is not. Man not a developed monkey. Not progress, but adaptation. Humanity not the goal of evo- lution. Change by slow divergence. No innate tend- ency toward progression. Spontaneous generation. III. THE ELEMENTS OF ORGANIC EVOLUTION Heredity. Irritability. Individuality. Natural selec- tion. Concessions of life. Self-activity. Altruism. Iso- lation. Nutrition in transmission. Survival of the exist- IV. THE FACTORS OF EVOLUTION FROM THE STAND- POINT OF EMBRYOLOGY. By Professor Edwin Embryology shows the method of evolution. Statement protoplasm relatively but not absolutely stable. Do ex- trinsic factors affect germinal protoplasm? Diminished nutrition. Changes in environment. Use and disuse. Mechanical conditions. Results of impact. Value of V. THE HEREDITY OF RICHARD ROE Formation of character. Hereditary tendencies. In- heritance of humanity. Inheritance of race characters. Individual characters. The germ cell. Protoplasm. Chromatin. Inequality of Nature's divisions. Atavism. The mid-parent. The thoroughbred. Changes through experience. Inheritance of acquired characters. Nature of acquired characters. Prenatal influences. Transmis- sion of impaired vitality. Ibsen's ghosts. Potentialities not character. The higher heredity. The unity of the ego. The ego a co-operation. Fame not greatness. Counting one's ancestors. Lineage of a little girl. All Englishmen of noble birth. Effect of primogeniture. The cell theory. The meaning of the term “cell." Uni- cellular and multicellular organisms. The essential parts of the cell. The protoplasm. The nucleus. Ka- ryokinesis. The chromosomes. Division of the centro- some. The spindle. Division of the chromosomes. Phases of cell division by karyokinesis. Direct division. Somatic and reproductive tissues. Differentiation of so- matic and reproductive tissues in Ascaris. Reproduction in Protozoa. Conjugation. Gradual differentiation of reproductive cells. Reproduction in Eudorina. Repro- duction in Metazoa. Fundamental identity of the germ cells. The egg cell. Maturation. The sperm cell. |