CHAPTER XXIV.

OBJECTIONS AGAINST, AND PROOFS OF THE TRUTH OF, THE THEORY OF DESCENT.

Objections to the Doctrine of Filiation.—Objections of Faith and Reason.—Immeasurable Length of the Geological Periods.—Transition Forms between Kindred Species.—Dependence of Stability of Form on Inheritance, and of the Variability of Form on Adaptation.—Origin of very Complicated Arrangement of Organisation.—Gradual Development of Instincts and Mental Activities.—Origin of à priori Knowledge from Knowledge a posteriori.—The Knowledge requisite for the Correct Understanding of the Doctrine of Filiation.—Necessary Interaction between Empiricism and Philosophy.—Proofs of the Theory of Descent.—Inner Causal-Connection between all the Biological Series of Phenomena.—The Direct Proof of the Theory of Selection.—Relation of the Theory of Descent to Anthropology.—Proofs of the Animal Origin of Man.—The Pithecoid Theory as an Inseparable Part of the Theory of Descent.—Induction and Deduction.—Gradual Development of the Human Mind.—Body and Mind.—Human Soul and Animal Soul.—A Glance at the Future 334

LIST OF WORKS REFERRED TO IN THE TEXT 371

APPENDIX (Explanation of the Plates) 379

INDEX 402

LIST OF ILLUSTRATIONS.

PLATES.

XV.—Hypothetical Sketch of the Monophyletic Origin of Man _Frontispiece_

IV.—Hand of Nine different Mammals _To face page_ 34

V.—Single-Stemmed, or Monophyletic, Pedigree of the Vegetable Kingdom ” 112

VI.—Historical Growth of the Six Great Stems of Animals ” 122

VII.—Animal Plants, or Zoophytes ” 140

VIII.—Star Fishes—First Generation _Between pp._ 170, 171

IX.—Star Fishes—Second Generation ” ” ”

X.—Nauplius-Youth-Form of Six Crab Fish ” 174, 175

XI.—Adult-Form of the same Six Crab Fish ” ” ”

XII.—Ascidia and Amphioxus ” 201, 202

XIII.—Ascidia and Amphioxus ” ” ”

XIV.—Single, or Monophyletic, Pedigree of Back-boned Animals _To face page_ 222

FIGURES.

8.—Protamœba Primitiva 52

9.—Bathybius Hæckelii 53

10.—Amœba Sphærococcus 54

11.—Euglena Striata 57

12.—Magosphæra Planula 58

13.—Labyrinthula Macrocystis 59

14.—Navicula Hippocampus 60

15.—Physarum Albipes 61

16.—Cyrtidosphæra Echinoides 66

17.—Caulerpa Denticulata 87

18.—Euastrum Rota 88

19.—Fucus Vesiculosus (egg of) 90

THE HISTORY OF CREATION.