Part 1

[Illustration: PLATE I.—Illustrating the results of Artificial Selection. Within historic times the small Wild Rock Pigeon has been evolved into the large Pouter. The figure illustrates the plasticity of a living organism.]

A FIRST BOOK IN ORGANIC EVOLUTION

BY D. KERFOOT SHUTE, A.B., M.D. OPHTHALMIC SURGEON TO THE UNIVERSITY HOSPITAL (COLUMBIAN) PROFESSOR OF ANATOMY IN THE COLUMBIAN UNIVERSITY

[Illustration]

CHICAGO THE OPEN COURT PUBLISHING COMPANY

LONDON: KEGAN PAUL, TRENCH, TRÜBNER & CO., LTD. PATERNOSTER HOUSE, CHARING CROSS ROAD

1899

COPYRIGHT BY THE OPEN COURT PUBLISHING CO. CHICAGO, U. S. A. 1899

_All rights reserved._

THIS LITTLE BOOK IS INSCRIBED TO

DR. THEODORE GILL,

NOT ONLY IN ADMIRATION FOR HIS HIGH SCHOLARSHIP AND EMINENT SCIENTIFIC ATTAINMENTS, BUT ALSO IN APPRECIATION OF MANY ACTS OF COURTESY AND KINDNESS TO THE AUTHOR.

PREFACE.

This little book has been written chiefly for the use of students in the Medical Department of the Columbian University. It is designed to serve only as an _introduction_ to the study of the Development Theory, and the subject has been presented, it is hoped, in a manner that will render it interesting and easily intelligible to the general reader.

The doctrine of Evolution itself enters so largely into all those departments of knowledge that especially concern the human race, and it has so profoundly modified our ideas with regard to the origin and destiny of man, that it has attained a commanding interest and become an almost necessary ingredient in what is called a liberal education.

An overwhelming majority of Anthropologists, Zoölogists, and Botanists, and a goodly number—constantly increasing—of Christian clergymen and laymen, have been almost compelled to believe in the truth of the Evolution Theory, whether they would or not, and they cannot but realize how very widely the theory extends into almost every department of human knowledge. No one, therefore, who aspires even to a moderate degree of intellectual culture, can well afford to exclude a clear understanding of what this Doctrine of Evolution really is. It is hoped this little work will render such a conception easily attainable.

The author makes no claim for originality, unless it be in the _manner_ of presenting the subject. He has utilized the facts collated by other observers, and sometimes quoted the exact language and expressions of well-known writers on Evolution, and has endeavored to put them together in a way that may be helpful to those who are beginning the study of the Evolution Theory.

No attempt has been made to prove the truth of the theory: this is assumed. The arguments in support of it are coextensive with our knowledge of Comparative Anatomy, Embryology, Physiology, Psychology, and many other sciences.

In the preparation of the book the author is especially indebted to his friend Prof. Theodore Gill, the eminent ichthyologist, for many valuable suggestions, and more particularly for his aid in constructing the Diagram of Development. He also desires to thank his friend Dr. A. F. A. King for his kindly assistance in preparing the manuscript for the press; and also his friend Dr. L. O. Howard, Chief of the U. S. Bureau of Entomology, for much valuable information and assistance.

D. K. SHUTE.

August 1, 1899, 1318 L Street, N. W., Washington, D. C.

CONTENTS.

PAGE

INTRODUCTION xiii System of Classification xiv Definition of Evolution xv

SECTION I.

ORGANIC CELLS: THE VISIBLE UNITS OF LIFE 3 Structure and Composition of Cells 4 Activities of Cells 7 Examples of Unicellular Animals and Plants 10 Mitosis 25 Maturation of the Human Ovum 29 Fertilization of the Human Ovum 29, 42 Segmentation of the Oösperm 31 Gastrulation 32

SECTION II.

HEREDITY WITH VARIATION 39 Examples of Variations 39 Illustrations of Heredity 40 Nucleus in Heredity 41 Heritages 47 Pseudo-Heredity 53 Environment and Variations 55 Acquired Characters 65 Pangenesis 66 Continuity of Germ-Cells 67 Modified Pangenesis 68 Heredity Stronger than Environment 75

SECTION III.

UNSTABLE ENVIRONMENT 81 Development of North America 85 Archæan Era 85 Palæozoic Era 86 Silurian Period 87 Devonian Period 87 Carboniferous Period 87 Jurassic Period 88 Cretaceous Period 88 Tertiary Period 89 Quaternary Period 89

SECTION IV.

TRANSMUTATIONS OF LIVING FORMS 93 Archæan Era 94 Table of Stratified Rocks and the Successive Appearance of Typical Life-Forms 95 Cambrian Period 96 Lower Silurian Period 96 Upper Silurian Period 98 Devonian Period 100 Carboniferous Period 102 Permian Period 104 Triassic Period 105 Jurassic Period 106 Cretaceous Period 108 Tertiary Period 110 Quaternary Period 113

SECTION V.

NATURAL SELECTION 119 Artificial Selection 120 Multiplication of Animals 122 Elimination of the Unfit 125 The Coloration of Animals and Environment 127 Protective Coloration 128 Protective Resemblance 138 Alluring Coloration 141 Warning Coloration 144 Mimicry 147 Recognition Marks 150 Sexual Selection 152 Insect Selection 160 Isolation of Varieties 166

SECTION VI.

EVOLUTION OF MAN 173 Development of the Frog 173 Development of Man 180 Useless Scaffolding in Man 191 Development of the Brain 199 The Brain and Psychic Phenomena 206 Evolution and Social Problems 222

SECTION VII.

CLASSIFICATION OF ANIMALS AND PLANTS 227 Protozoa 229 Porifera 230 Cœlenterata 230 Echinodermata 231 Vermes 232 Arthropoda 233 Mollusca 233 Vertebrata 234 Tunicata 234 Leptocardii 235 Marsipobranchii 235 Pisces 236 Amphibia 237 Reptilia 238 Aves 238 Mammalia 239 Primates 239 Lemuroidea 240 Anthropoidea 241 Hapalidæ 242 Cebidæ 242 Cercopithecidæ 242 Simiidæ 243 Hominidæ 243 Flowerless Plants 244 Flowering Plants 244

SECTION VIII.

WORKS OF REFERENCE 247

SECTION IX.

GLOSSARY 255

SECTION X.

INDEX 277

ILLUSTRATIONS.

FIG. PAGE

1. Diagram of a Cell. (_Drawn by Mr. E. P. Copeland from a sketch by the Author._) 5

2. Stylonychia. (_Drawn by Mr. E. P. Copeland._) 9

3. Amœba. (_Drawn by Mr. E. P. Copeland._) 11

4. Rotalia. (_Drawn by Dr. A. L. Lawrence._) 12

5. Difflugia. (_Drawn by Dr. A. L. Lawrence._) 17

6. Noctiluca. (_Drawn by Dr. A. L. Lawrence._) 18

7. Gromia. (_Drawn by Dr. A. L. Lawrence._) 21

8. Diagram Illustrating Mitosis. (_Drawn by Mr. E. P. Copeland from a sketch by the Author._) 26

9. Diagram Illustrating the Maturation and Fertilization of the Ovum. (_Drawn by Mr. E. P. Copeland from a sketch by the Author._) 30

10. Diagram Illustrating Segmentation and Gastrulation. (_Drawn by Mr. E. P. Copeland from a sketch by the Author._) 34

11. Archæan North America. (_From a drawing in Shaler’s “First Book in Geology.”_) 84

12. Cretaceous North America. (_From a drawing in Shaler’s “First Book in Geology.”_) 86

13. Tertiary North America. (_From a drawing in Shaler’s “First Book in Geology.”_) 89

14. Genesis of Horse’s Feet. (_Drawn by Mr. E. P. Copeland._) 112

15. Bipes, Cheirotes, and Snake. (_From a drawing in Shaler’s “First Book in Geology.”_) 114

16. Domesticated Pig and Wild Boar. (_From Romanes’ “Darwin and After Darwin.”_) 121

17. Tadpoles and Frog. (_Drawn by Dr. A. L. Lawrence._) 175

18. Diagram of Development. (_Drawn by Mr. B. H. Esterly from a sketch by the Author._) 183

19. Brain of Fish. (_Drawn by Mr. B. H. Esterly from specimens of the Author._) 198

20. Brain of Reptile. (_Drawn by Mr. B. H. Esterly from specimens of the Author._) 199

21. Brain of a Marsupial. (_Drawn by Mr. B. H. Esterly from specimens of the Author._) 200

22. Brain of a Lemur. (_Modified by Mr. B. H. Esterly from Flower._) 201

23. Ideal Sections of Brains. (_Modified from Le Conte. Drawn by Dr. A. L. Lawrence from a sketch by the Author._) 202

24. Brain of Human Fœtus—Fish Phase. (_Drawn by Mr. B. H. Esterly from specimens of the Author._) 204

25. Brain of Human Fœtus—Reptile Phase. (_Drawn by Mr. B. H. Esterly from specimens of the Author._) 204

26. Brain of Human Fœtus—Marsupial Phase. Side View. (_Drawn by Mr. B. H. Esterly from specimens of the Author._) 204

27. Brain of Human Fœtus—Marsupial Phase. Dorsal View. (_Drawn by Mr. B. H. Esterly from specimens of the Author._) 205

COLORED PLATES

PLATE FACING PAGE

I. Wild Rock Pigeon and Pouter. (_Drawn by Mr. J. L. Ridgway from specimens in the Smithsonian Institution._) Frontispiece

II. Butterflies. (_Drawn by Miss L. Sullivan from specimens in the United States Bureau of Entomology._) 138

III. Caterpillar of Geometer Moth. (_Drawn by Miss L. Sullivan from specimens in the United States Bureau of Entomology._) 142

V. Spider on Flower. (_Drawn by Miss L. Sullivan from a plate in McCook’s “American Spiders.”_) 144

VI. Elaps and Erythrolamprus. (_Modified by Mr. J. L. Ridgway from a figure in Romanes’ “Darwin and After Darwin.”_) 146

VII. Salamandra maculosa. (_Drawn by Mr. J. L. Ridgway from specimens in the United States National Museum._) 148

VIII. Paradise Birds. (_Drawn by Mr. J. L. Ridgway from specimens in the Smithsonian Institution._) 152

IX. Primrose Flowers. (_Drawn by Miss L. Sullivan from specimens._) 162

X. Bee Fertilizing Flower. (_Drawn by Miss L. Sullivan from specimens in the United States Bureau of Entomology._) 164

PLATES ENGRAVED IN BLACK AND WHITE

IV. Leaf-hoppers. (_Drawn by Miss L. Sullivan from drawings collected by Dr. L. O. Howard._) 140

XI. Babies’ Grasping Power. (_From a Photograph taken by Dr. Louis Robinson._) 192

XII. Brain of Man. (_From Carus’ “The Soul of Man.”_) 202

INTRODUCTION.

It is extremely difficult to realize the variety, wealth, and grandeur of animal and plant life as they exist on the globe to-day. Even if we endeavor to recall, in imagination, all that we have seen in streams and woodland, in ponds and rivers, in meadows, and in the air; even when we call to mind the multifarious specimens we have beheld in all the museums of natural history we have visited, and remember the most vivid descriptions that we have ever read of the wealth of tropical life;—even then we have only the faintest conception of the multitude and variety of _living forms_, not to mention the _vanished hosts of bygone ages_.

It has always been the endeavor of students of nature to reduce this great host of living creatures to order by some system of classification. First one system of classification was adopted, and then another, with the progress of Botany and Zoölogy, until eventually, before the theory of evolution was entertained by scientific men, that system was adopted which naturalists likened to a tree. In this system, those lowest organisms which cannot properly be called either animals or plants, may be represented by a short trunk. Soon this short trunk divides into two large trunks, one of which represents the animal kingdom and the other the vegetable kingdom. Each of these trunks then sends off large branches representing classes, from which smaller and more numerous branches, representing orders, are given off. From these, other branches and sub-branches are separated, representing families and genera, and finally the terminal twigs or leaves represent species.

In this tree, while there is a general advance in organization from below upwards, there are many deviations in this respect. Some leaves may be growing on different branches at the same level, which means that species belonging to widely divergent classes or orders may still possess an equal grade of organization. On the same branch there may be growing leaves at different levels. This means that one species may be more highly organized than another belonging to the same class. Not only may all living species be classified in the form of a family tree, but all the extinct hosts of species that lived in the ages of the past may be similarly classified. _If all the animals that have ever lived on the globe should be represented by a tree, those existing on the earth to-day would be indicated by the topmost twigs and leaves, while the extinct forms would be represented by the trunk and main branches._ (Vid. Diagram of Development.)

The detecting of this tree-like arrangement of species in nature is the progressive work of naturalists for centuries past. At about the commencement of the present century, when it was finally detected, naturalists were unable to understand the significance of it. They did not perceive the underlying principle that accounts for the fact that groups of living forms have such natural affinities that they are arranged like a family tree.

When Darwin came upon the scene and found that his predecessors had already empirically worked out the tree-like system of classification, he convinced naturalists that the great underlying principle of this system was =Heredity=; and that, therefore, the grouping of living and extinct organisms in a family tree according to their natural affinities is a grouping based upon genetic affinities; and further that the ultimate meaning of classification is the tracing of lines of pedigree. This signifies that all the creatures living on the globe to-day, and all the hosts that lived in the ages of the past, are blood relations in greater or less degree, and that they have all been evolved from simple microscopic creatures that appeared on the globe at the dawn of life. All organisms, then, have undergone an evolution.

The factors of fundamental importance in the study of the theory of =Evolution=, or the doctrine of the Transmutations of Organisms, are =Cells=, =Heredity= and =Variation=, =Environment=, =Natural Selection=, and =Isolation=.

_The evolution of an organism means its descent from preceding organisms with continuous adaptation to its Environment. Its adaptation occurs chiefly, if not entirely, through the Natural Selection of its useful Variations, and the tending of these variations to be transmitted to the offspring by the forces of Heredity. The summation of the variations, by Heredity and Isolation, leads ultimately to specific, generic, ordinal, and other differences in the descendants; leads, in other words, to the transmutations of organisms._

An organism consists of two great groups of _structural units_ called _cells_,—=Germ-Cells= and =Body-Cells=,—harmoniously associated together. As far as Evolution is concerned, the most fundamental parts of an organism are the Germ-Cells.

In order that the reader may have a working knowledge of the wonderful powers of Germ-Cells and their progeny, it is vitally important that some concrete illustrations of the activities of different kinds of cells should be given.

SECTION I.

ORGANIC CELLS: THE VISIBLE UNITS OF LIFE.

ORGANIC CELLS: THE VISIBLE UNITS OF LIFE.

In the sanctuary of S. Vitale at Ravenna, in Italy, is a very interesting representation, in mosaic pictures, and over life-size, of the Emperor Justinian and his Empress Theodora, attended by a numerous suite of ladies and courtiers. The mosaics are small bits of glass, of varying pattern and color, cemented together so nicely as to form beautiful delineations of the Emperor and his attendants.

The bits of glass or mosaics that form the figures may very appropriately be called _structural units_.

The body of man, a bird, a lizard, an oak tree, and many other animals and plants, may usefully be compared to such mosaic figures; for, just as the mosaic figure has its structural unit, the little bit of glass or stone, called the mosaic; so the bodies of men, birds, and other creatures may be looked upon as infinitely complex figures formed of minute mosaics called _cells_.

The groups of minute mosaics or _cells_ that make up the bodies of animals and plants differ profoundly from the mosaics that form the figures of the dead Emperor and his companions, inasmuch as each mosaic or cell of the animal or plant body is so small as to require the microscope to reveal it; also each mosaic of the living animal or plant is a living mosaic or cell, in that it can absorb food, digest it, assimilate it, grow, and multiply in numbers. Cells, then, are the _morphological or structural units_ which compose the bodies of all living creatures.

All animals and plants begin life as _single_ cells, which, in the vast majority of cases, are microscopic in size. Those that remain single cells, and dissociated throughout life, are called _Unicellular_ Animals (Protozoa) and Plants (Protophyta), and are to be seen mostly by the microscope alone; but those which, by multiplication and growth, form large numbers of cells that remain associated together as in the body of a bird or lizard, are called _Multicellular_ Animals (Metazoa) or Plants (Metaphyta).

A cell (Fig. 1) is a _nucleated lump of protoplasm_, or cytoplasm, and most often of microscopic size and more or less covered on its exterior by, and holding in its interior, various products and formations resulting from its activity, which are called _metaplasm_. Since the protoplasm of a cell, under the microscope, presents a superficial resemblance to a minute speck of that jelly-like substance (albumen) which forms the white of an egg, it is often called an albumenoid substance. But it is very misleading to use such an expression, for protoplasm is not a single chemical substance of great complexity; but it is rather composed of a large number of different chemical substances of great complexity. Many of these substances, it is true, are albumenoid in character. The same is true as to the chemical complexity of the nucleus, which is a physically and chemically differentiated part of the protoplasm.

The protoplasm contains certain globulins, and also albumins and peptones; it also contains large quantities of nucleo-albumins, with other substances. The nucleus not only contains these same substances, but also nuclein and nucleo-proteids. It is important to state that nuclein consists of an albumin and nucleic acid.

[Illustration: FIG. 1.—Diagram of a Cell, highly magnified.]

The protoplasm, structurally, is made up of threads forming a complex, sponge-like substance, or reticulum, called _spongioplasm_; and in the meshes of the spongioplasm is a more or less fluid-like substance known as _hyaloplasm_: suspended in the hyaloplasm are various kinds of living bodies known as _plastids_, besides various products resulting from the activity of the protoplasm and which are designated _metaplasm_.

In many cells the protoplasm has formed on its periphery a layer of metaplasm which is frequently called a cell-wall. This cell-wall prevents amœboid movements of the protoplasm, and a cell possessing it is said to be _encysted_.

In many cells, especially vegetable ones, will also be observed clear spaces termed _vacuoles_. These vacuoles contain water with various chemical substances held in solution, which serve the purpose chiefly of food-reservoirs.

The nucleus also is formed of threads called _nuclear or chromatin threads_ (_chromosomes_), the interstices of which are filled with hyaloplasm or _achromatin_. In the nucleus can also be observed the nucleolus.

The protoplasmic and nuclear threads show various structural modifications in different regions and under different physiological states of the cell.

As will be observed later on, the nuclear threads are of special interest to the student of heredity. They may in one phase of cell-activity look like one thread forming an inextricable network, while in other phases they may look like thick, short, distinct rods.

The _centrosome_ (Fig. 1), with its enveloping attraction-sphere, constitutes another fundamentally important part of the cell. It is especially concerned with the phenomena of cell division and multiplication.

Just as the living body consists of an infinitely complex figure of living mosaics termed cells, so the cell itself consists of an infinitely complex figure of still smaller living mosaics called, by Spencer, _Physiological Units_. These units have been given different names by various writers, viz.: by Darwin, _gemmæ_ (gemmules); by de Vries, _pangennæ_; by Hertwig, _idioblasts_; by Weismann, _biophors_, etc., etc.

Like the atom of the chemist and the molecule of the physicist, the physiological unit of the biologist is merely at present an intellectual conception, yet it is, at the same time, an intellectual necessity and plays a very important part as the theoretical component of many vital questions. Just as the cells are the _visible_ units of life, so the physiological units are the _invisible_ units.

The physiological activities of cells are those that pertain to their _nutrition_ and _reproduction_.

The nutrition of cells includes all processes that are subservient to their life and well-being, such as irritability, contractility, absorption of food, its digestion and assimilation, secretion, etc.

In consequence of the wonderful _nutritive_ activities of cells, we may well speak of them as marvelous magicians. Hertwig, following Haeckel, speaks of many cells as being _builders_. In the same spirit, we can say that multitudes of cells are expert chemists, artists, sculptors, mathematicians, and so on, in that they make all the myriad chemical products of organic nature, such as spices, pigments, sugars, starches, acids, perfumes, and numerous other substances; they paint in colors that rival the hues of the rainbow; they construct all of the beautiful forms in the animal and plant worlds; and they draw lines as straight and curves as graceful as the most expert mathematician.

One of the most important _reproductive_ activities of a cell is _mitosis_ (see below). Mitosis essentially consists of a series of processes by which each _nuclear thread_ of the nucleus _splits longitudinally into two equal parts_, and then these equivalent parts separate from each other, so that from the one nucleus we get two smaller nuclei. Then each of these smaller nuclei appropriates its share of the enveloping protoplasm, finally splitting it into two parts. Thus from the larger cell (nucleated piece of protoplasm) we get two smaller cells (two smaller nucleated pieces of protoplasm). In technical language, we say that the larger cell is the _mother cell_, and the two smaller cells that it has divided into are the _daughter cells_. In consequence of the method of mitosis, the two daughter cells very frequently are exactly like the mother cell, except in size. But by the absorption of nutriment, and through digestion and assimilation, they grow and finally become exactly like the mother cell. This is the simplest illustration of _heredity_. The reproductive process may be repeated very many times, so that from one cell we may get millions of cells.[1]

It is necessary to assume that the nutritive and reproductive activities of _cells_ are based upon and controlled by the nutritive and reproductive activities of the _physiological units_, inasmuch as these are the ultimate living units.

In the activities of a cell the nucleus and protoplasm are intimately correlated with one another.

The nucleus is looked upon by the majority of cytologists as the _formative center_ of the cell in a chemical, and also, consequently, in a morphological, sense. Active exchanges of material take place between the nucleus and the protoplasm during the nutritive processes of the cell. Possibly this may be altogether a chemical process, or possibly it may be due, as Hertwig suggests, to the migrations of the _physiological units_ as carriers and elaborators.

In these exchanges, and in the upbuilding chemical activities (anabolism) of the cell, the nucleic acid plays a leading part. Here the nucleic acid in the physiological units of the nuclear threads, combines with albumins from the protoplasm, forming nuclein. Much of this nuclein, undergoing further elaboration, is passed into the protoplasm as one of its finished products (metaplasm). The more purely nutritive the activity of a cell, the more nuclein its nuclear threads contain; on the other hand, when the cell is in the phase of reproductive activity, the nucleus contains little nuclein, and is almost entirely composed of pure nucleic acid.

[Illustration: FIG. 2.—Stylonychia: c, an entire animal, showing planes of section; the middle piece of c contains two nuclei and can regenerate a perfect animal; a, and b, contain no nuclei,—they live and swim about for a while and then die.]