| [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
CHAPTER I
GENERAL INTRODUCTION
Although a few cases of regeneration were spoken of by Aristotle and by Pliny, the subject first attracted general attention through the remarkable observations and experiments of the Abbé Trembley. His interest was drawn to certain fresh-water polyps, hydras, that were new to him, and in order to find out if the organisms were plants or animals he tried the effect of cutting them into pieces; for it was generally known that pieces of a plant made a new plant, but if an animal were cut into pieces, the pieces died. Trembley found that the polyp, if cut in two, produced two polyps. Logically, he should have concluded that the new form was a plant; but from other observations, as to its method of feeding and of movement, Trembley concluded that the polyp was an animal, and that the property of developing a new organism from a part must belong to animals as well as to plants. “I felt,” he says, “strongly that nature is too vast, and too little known, for us to decide without temerity that this or that property is not found in one or another class of organized bodies.”
Trembley’s first experiments were made in 1740, and the remarkable results were communicated by letter to several other naturalists. It came about in this way that before Trembley’s memoir had appeared, in 1744, his results were generally known, and several other observers had repeated his experiments, and extended them to other forms, and had even published an account of their own experiments, recognizing Trembley, however, as the first discoverer. Thus Réaumur described, in 1742, a number of other forms in which regeneration takes place; and Bonnet, in 1745, also described some experiments that he had made during the four preceding years. Widespread interest was aroused by these results, and many different kinds of animals were experimented with to test their power of regeneration. Most important of these new discoveries were those of Spallanzani, who published a short preliminary statement of his results, in 1768, in his Prodromo.
Trembley found that when a hydra is cut in two, the time required for the development of the new individuals is less during warm than during cold weather. He also found that if a hydra is cut into three or four parts, each part produces a new individual. If these new hydras are fed until they grow to full size, and are then again cut into pieces, each piece will produce a new polyp. The new animals were kept in some cases for two years, and behaved in all respects as do ordinary polyps.
Trembley also found that if the anterior, or head-end, with its tentacles, is cut off, it also will make a new animal. If a hydra is cut lengthwise into two parts, the edges roll in and meet, and in an hour, or less, the characteristic form may be again assumed. New arms may appear later on the new individual. If a hydra is split lengthwise into four pieces, each piece will also produce a new polyp.