Chapter I: Preface

This volume is the outcome of a course of five lectures on “Regeneration and Experimental Embryology,” given in Columbia University in January, 1900. The subjects dealt with in the lectures are here more fully treated and are supplemented by the discussion of a number of related topics. During the last few years the problems connected with the regeneration of organisms have interested a large number of biologists, and much new work has been done in this field; especially in connection with the regenerative phenomena of the egg and early embryo. The development of isolated cells or blastomeres has, for instance, aroused widespread interest. It has become clearer, as new discoveries have been made, that the latter phenomena are only special cases of the general phenomena of regeneration in organisms, so that the results have been treated from this point of view in the present volume.

If it should appear that at times I have gone out of my way to attack the hypothesis of preformed nuclear germs, and also the theory of natural selection as applied to regeneration, I trust that the importance of the questions involved may be an excuse for the criticism.

If I may be pardoned a further word of personal import, I should like to add that it has seemed to me that far more essential than each special question with which the biologist has to deal is his attitude toward the general subject of biology as a science. Never before in the history of biology has this been more important than at the present time, when we so often fail to realize which problems are really scientific and which methods are legitimate for the solution of these problems. The custom of indulging in exaggerated and unverifiable speculation bids fair to dull our appreciation for hypotheses whose chief value lies in the possibility of their verification; but those who have spent their time and their imagination in such speculations cannot hope for long to hold their own against the slow but certain advance of a scientific spirit of investigation of organic phenomena. The historical questions with which so many problems seem to be connected, and for which there is no rigorous experimental test, are perhaps responsible for the loose way in which many problems in biology are treated, where fancy too often supplies the place of demonstration. If, then, I have tried to use my material in such a way as to turn the evidence against some of the uncritical hypotheses of biology, I trust that the book may have a wider bearing than simply as a treatment of the problems of regeneration.

I wish to acknowledge my many obligations to Professor H. F. Osborn and to Professor E. B. Wilson for friendly criticism and advice; and in connection with the revision of the text I am greatly indebted to Professor J. W. Warren, to Professor W. M. Wheeler, to Professor G. H. Parker, and to Professor Leo Loeb.

BRYN MAWR COLLEGE, PENNSYLVANIA,

June 11, 1901.

CONTENTS

CHAPTER I

GENERAL INTRODUCTION

PAGE

Historical Account of the Work on Regeneration of Trembley,
Bonnet, and Spallanzani 1
Some Further Examples of Regeneration 6
Definition of Terms 19

CHAPTER II
THE EXTERNAL FACTORS OF REGENERATION IN ANIMALS

The Effect of Temperature 26
The Effect of Food 27
The Effect of Light 29
The Effect of Gravity 30
The Effect of Contact 33
The Effect of Chemical Changes in the Environment 35
General Conclusions 36

CHAPTER III
THE INTERNAL FACTORS OF REGENERATION IN ANIMALS

Polarity and Heteromorphosis 38
Lateral Regeneration 43
Regeneration from an Oblique Surface 44
The Influence of Internal Organs at the Cut-surface 52
The Influence of the Amount of New Material 54
The Influence of the Old Parts on the New 62
The Influence of the Nucleus on Regeneration 65
The Closing in of Cut-edges 69

CHAPTER IV
REGENERATION IN PLANTS

Regeneration in Flowering Plants 71
Regeneration in Liverworts, Mosses, and Moulds 84
Hypothesis of Formative Stuffs 88

CHAPTER V
REGENERATION AND LIABILITY TO INJURY

Examples of Supposed Connection between Regeneration and
Liability to Injury 92
Regeneration in Different Parts of the Body 97
Regeneration throughout the Animal Kingdom 103
Regeneration and the Theory of Natural Selection 108

CHAPTER VI
REGENERATION OF INTERNAL ORGANS. HYPERTROPHY. ATROPHY

Regeneration of Liver, Eye, Kidney, Salivary Glands, Bones,
Muscles, Nerves,
Brain, and Cord of Vertebrates 111
Examples of Hypertrophy 115
Theories of Hypertrophy 118
Atrophy 123
Incomplete Regeneration 125

CHAPTER VII
PHYSIOLOGICAL REGENERATION

Supposed Relation between Physiological Regeneration and Restorative
Regeneration 128
Regeneration and Growth 131
Double Structures 135

CHAPTER VIII
SELF-DIVISION AND REGENERATION. BUDDING AND REGENERATION. AUTOTOMY.
THEORIES OF AUTOTOMY

Review of Groups in which Self-division occurs 142
Division in Plane of Least Resistance 144
Review of Groups in which Budding occurs. Relation of Budding+
to Regeneration 149
Autotomy 150
Theories of Autotomy 155

CHAPTER IX
GRAFTING AND REGENERATION

Examples of Grafting in Hydra, Tubularia, Planarians, Earthworms,
Tadpoles 159
Grafting Pieces of Organs in Other Parts of the Body in
Higher Animals 178
Grafting of Parts of Embryos of the Frog 182
Union of Two Eggs to form One Embryo 188

CHAPTER X
THE ORIGIN OF NEW CELLS AND TISSUES

Origin of New Cells in Annelids 190
Origin of the New Lens in the Eye of Salamanders 203
The Part played by the “Germ-layers” in Regeneration 207
The Supposed Repetition of Phylogenetic and Ontogenetic
Processes in Regeneration 212

CHAPTER XI
REGENERATION IN EGG AND EMBRYO

Introduction 216
Regeneration in Egg of Frog 217
Regeneration in Egg of Sea-urchin 228
Regeneration in Other Forms: Amphioxus, Ascidian, Ctenophore,
Snail, Jelly-fish, Fish 236

CHAPTER XII
THEORIES OF DEVELOPMENT

Theories of Isotropy and of Totipotence of Cells 242
Theory of Qualitative Division of Nucleus 243
Theory of Equivalency of Cells 244
Theory of the Organized Structure of the Protoplasm 246
Theory of Cells as Units 250
Further Analysis of Theories of Qualitative Nuclear Divisions and
of the Equivalency of Blastomeres 252
Driesch’s Analytical Theory, Criticism, and Later Theories of
Driesch 253
Conclusions 256

CHAPTER XIII
THEORIES OF REGENERATION

Pre-formation Theory 260
Comparison with Growth of Crystal 263
Completing Theory 264
Theory of Formative Stuffs 265
Conclusions 269
Theory of Tensions controlling Growth 271

CHAPTER XIV
GENERAL CONSIDERATIONS AND CONCLUSIONS

Organization 277
Machine Theory of Development and of Regeneration 283
Teleology 283
“Action at a Distance” 284
Definition of Terms: Cause, Stimulus, Factor, Force, Formative
Force, Organization 287
Regeneration as a Phenomenon of Adaptation 288

LITERATURE 293

INDEX 311

REGENERATION