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diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..6833f05 --- /dev/null +++ b/.gitattributes @@ -0,0 +1,3 @@ +* text=auto +*.txt text +*.md text diff --git a/29422-8.txt b/29422-8.txt new file mode 100644 index 0000000..1e0c12e --- /dev/null +++ b/29422-8.txt @@ -0,0 +1,7739 @@ +Project Gutenberg's The Meaning of Evolution, by Samuel Christian Schmucker + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: The Meaning of Evolution + +Author: Samuel Christian Schmucker + +Release Date: July 16, 2009 [EBook #29422] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK THE MEANING OF EVOLUTION *** + + + + +Produced by Juliet Sutherland, Chris Logan and the Online +Distributed Proofreading Team at http://www.pgdp.net + + + + + + + + + +THE MEANING OF +EVOLUTION + +BY + +SAMUEL CHRISTIAN SCHMUCKER, PH.D. + +PROFESSOR OF BIOLOGICAL SCIENCES IN THE +WEST CHESTER STATE NORMAL SCHOOL +WEST CHESTER, PA. + +[Illustration] + +The Chautauqua Press +CHAUTAUQUA, NEW YORK +MCMXIII + + + + +COPYRIGHT, 1913 +BY THE MACMILLAN COMPANY + + +Set up and electrotyped. Published June, 1913 + + + + +CONTENTS + + + CHAPTER PAGE + + A FOREWORD 1 + + I. EVOLUTION BEFORE DARWIN 7 + + II. DARWIN AND WALLACE 21 + + III. THE UNDERLYING IDEA 44 + + IV. ADAPTATION FOR THE INDIVIDUAL 87 + + V. ADAPTATION FOR THE SPECIES 125 + + VI. LIFE IN THE PAST 149 + + VII. HOW THE MAMMALS DEVELOPED 192 + + VIII. THE STORY OF THE HORSE 220 + + IX. EVOLUTION SINCE DARWIN 233 + + X. THE FUTURE EVOLUTION OF MAN 249 + + XI. SCIENCE AND THE BOOK 274 + + INDEX 293 + + APPENDIX 299 + + + + +A FOREWORD + + +Before my window lies an enchanting landscape. It embraces a stretch +of open rolling country, beautiful as the eye could wish to rest upon. +The sun with its slanting rays is not giving it heat enough in these +winter months to make it blossom in its radiant beauty, but the mind +goes easily back through the few brown months to the time when the +field not far away was waving with its rich yellow grain so soon to be +food for those who planted it. Beyond this field lies an orchard +where, in regular and orderly rows, stand the apple trees whose bright +blossoms in the spring make the landscape so beautiful and whose fruit +in the fall serves so richly for our enjoyment. A little farther on, a +pasture is filled with sleek-coated cows, feeding quietly and +patiently until the evening when they will return to their stalls to +yield their rich milk. Still farther on lies a tract of forest. The +varied shades of the beeches, the tulip poplars and the chestnuts make +an exquisite contrast and give to the landscape its attractive +background framed in by a distant hill. Behind this hill flows a +mighty river carrying on its breast the ships by which we share the +over-abundance of our own blessings with our brothers on the other +side of the sea, from whom in turn we receive of their overplus. +Beyond this teeming river lies a level stretch of fertile land and +then the mighty ocean. On one side of the scene runs a busy highway. +Along this men pass and repass, some on foot, others drawn by their +patient and submissive horses. Still others are carried by the +new-found power of the sunshine imprisoned beneath the rocks in the +oil that has been forming ever since the sun shone down upon the great +forests of the far distant past. + +In a pathway to one side, some children are playing. One of them has +laid upon the ground a rectangle of stones divided into four and her +little mind sees before her the house which is teaching her to get +ready for the work that shall come to her in later life. Meanwhile her +short-haired companion is prancing around astride a stick; he too, +little as he suspects it, is getting ready for life. + +It needs little reflection to realize that the scene has not always +been what it is. The underlying ground has surely been there longest, +its age vying only with that of the bounding ocean that beats upon the +shore and works the sand into fantastic stretches. The forest has been +there long and so has the stream; the road perhaps ranks next in age; +then come the orchard trees, and most recent of all the waving grain. +People come and go but form no stable part of this landscape. We know +how the grain came to be there, and we understand the orderly +arrangement of the orchard trees; the road too we can explain. How +came the stream there, and how the forest trees? Have they always been +there, or did they too have a beginning? Was there a time when there +was no ocean? When was this time? How came they there? + +When the lisping lips of my young child asked me, "Papa, who made me?" +I told him "God," and he knew enough and was content with his +knowledge. After a while he grew older and his inquisitive spirit +began to puzzle with the question of how God had made him. When his +growing mind was ready for the new knowledge I took him to my side and +told him the great mystery of life. I told him how he owed to his +father and to his mother the beginnings of his life, how God gave him +to us. Now a new era opened in his childish mind. As he grows on to +greater maturity he cannot help wondering how the first man was made, +how the trees, and the world came to be. He is no longer satisfied +with the simple statement that God made them. His eager mind wants to +know, if may be, how God made them. + +So, in the distant past, in the childhood of our race, the question +was asked, "Who made us?" and the answer was "God." Men formed their +simple conception at that time of how He did it. As the centuries +rolled by and the children of men have learned from creation the story +of its origin a riper and richer knowledge has given them a broader +and finer conception. No less does the reverent student believe that +God created the earth, but he no longer thinks of God as working, as +man works. He no longer feels that it is impious to attempt to read +God's plan in His work; to see how this work has arisen, to see, if +may be, what there is ahead. + +This is one of the tasks to which science is now giving itself. The +answer is uncertain and halting. A few things seem clear; others seem +to be nearly certain; of still others we can only say that for the +present we must be content with the knowledge we have. But if we take +the best we have and work over it thoughtfully and carefully, the +better will slowly come, and in time we shall know far more than we +now suspect. Meanwhile, it is the attempt of this book to give to +people whose training is other than scientific some conception of this +great story of creation. Without dogmatic certainty but without +indecision it tries to tell what modern science thinks as to the great +problems of life. It tries to describe the possible origin of animals +and plants, their slow advance, the length of their steady uplift, the +forces that brought it about. It tries to tell a little of the men +who have helped to develop the great idea of evolution, of the great +men who persuaded the scientific world of its truth, and of the later +minds that are modifying and enlarging the idea of the master +evolutionist. It tries to tell what science perhaps vaguely hopes as +to the future. What are we to be? Can we help the great advance? + + + + +The Meaning of Evolution + + + + +CHAPTER I + +EVOLUTION BEFORE DARWIN + + +Ever since men have been able to think they must have puzzled out for +themselves some way of accounting for their own beginnings. Every +savage tribe with whom we have any intimate acquaintance has some +story that accounts for the origin of the tribe at least, and often +for the beginning of the world. These stories are handed down from +generation to generation and are scarcely questioned in the thought of +most men. In early Greece there was a succession of men whom the world +calls philosophers. These men thought earnestly and deeply on all +kinds of questions. Their method was not our method. The plan of +making a long series of observations, before coming to any conclusion, +was not the habit of their minds. They reasoned out on general +principles what seemed to them must have been the origin of the world. +It is not strange that among these should come, now and then, some one +who in some passage or other should show that there had come to his +mind at least a glimmer of the thought that was later to develop into +the great idea which the modern world calls evolution. + +Among the earliest of these was Anaximander, who lived 600 years +before Christ. He thought that the earth was at first a fluid. +Gradually this fluid began to dry and grow thicker, and here and +there, where it thickened most, dry land appeared. When this dry land +had become firm enough to serve as his home, man came up from the +water in the form of a fish. Slowly and gradually the fish, struggling +about on the land, gained for himself the limbs and members he needed +for his new situation and developed into a man. After him other +animals came up in much the same fashion, then the plants, until the +whole world was clothed with its present inhabitants. + +One hundred and fifty years later Empedocles announced a new thought. +He said that in the beginnings there were all sorts of strange, +incomplete, and misjointed monsters which swarmed upon the earth, +having sprung up out of the earth itself. Each was a chaos of the +limbs which afterward were to belong to other animals which needed +them more. Slowly and gradually an interchanging came about by which +appropriate limbs fastened themselves to the proper animals. The last +of these misjointed creatures is the one known as the centaur, +half-man--half-horse. After a while, when all the members had found +their proper places, the animals were complete. In one respect this +opinion foreshadowed our later idea. It suggested that the more +perfect animals had arisen out of the less perfect and that the change +came gradually. + +Then came Anaxagoras, who was the first to believe that there was +intelligent design back of the creation of animals and of plants. He +thought there had originally been a slime in which were the germs of +all the later plants, animals, and minerals, mixed in a chaos. Slowly +order arose. Out of the mixture settled first the minerals forming the +earth, with the air floating above it, and above the air was the +ether. Out of the air the germs of plants settled upon the earth, and +vegetation covered the mineral floor. Then from the ether came the +germs of animals and of men. These settled among the plants and sprang +up into the animals of the world, as well as the people. + +The greatest scientific thinker of early Greece was Aristotle. He had +lived by the seashore and knew better than any other man of his times +the exquisite seaweeds and the still more beautiful marine animals. He +was the first to think of them as a linked series, the higher +developing out of the lower under the pressure of what he called a +perfecting principle. Out of the inanimate rocks had sprung the marine +plants--the seaweeds. From these had developed first "plant animals" +like the sea anemones and the sponges. These grew attached to the +rocks, as plants do. With higher development came locomotion, with +ever-increasing energy. At last man arose, the crown of all creation. +Presiding over all this advance is the "efficient cause," God. +Aristotle rejected entirely the earlier ideas that any of this work +came about by chance. He was certain of the existence of plan and +purpose in the development. + +Just a little before the time of Christ the Latin poet, Lucretius, +wrote a poem on "The Nature of Things." Here he describes how in the +early years the beginnings of things in small, disjointed fashion +moved about among each other at first in utter confusion, each trying +itself with the other. After many trials the proper members came +together. When they had been thus placed the warmth of the sun shining +down upon the earth helped the earth to reproduce the same sort of +creatures. So living things came up and flourished. The poem expresses +many beautiful ideas, but the underlying conceptions lack the unity +and grandeur that marked Aristotle's work, which later was the potent +influence in shaping men's minds. It died out after a while, only to +awake in the Renaissance with marvelous vitality, starting the world +to think afresh great thoughts that would not die, but would grow from +that time on with ever-widening scope. + +Among the Jews and early Christians the stately and beautiful account +in Genesis sufficed for all the needs of minds fully occupied with +other questions. With the growth of philosophy among Christian minds +again came the need of a satisfactory solution. St. Augustine was +probably the greatest of the so-called "Fathers" of the church. His +mind was eminently philosophical, and he was learned in the writings +of the older Greeks. He believed the language of Genesis to mean that +in the beginning God planted in chaos the seed that afterward sprang +up into the heavens and the earth. He further says that the six days +of creation were not days of time, but a series of causes, and that, +in the order described as these six days, God planted in chaos the +various beginnings of things. These in the fullness of time sprang up +into the world as we know it now. The problem was not a question about +which the church cared to trouble itself, and with the oncoming of the +Dark Ages the whole matter dropped nearly out of the thoughts of men. + +When the times began to lighten we find the schoolmen, among the +greatest of whom was Thomas Aquinas. Referring especially to the +authority of his master, St. Augustine, he says that it would be easy +mistakenly to believe that the author of Genesis meant to convey the +idea that on each of the six days certain acts of creation were +performed. It is quite evident, thinks Aquinas, that in those early +times God only created the germs of things and put into the earth +powers which should later become active. After the Creator had thus +endowed the earth he rested from the work, which proceeded to develop +under the influence of these first germs. + +Nearly four hundred years later, when Europe had finally awakened out +of the deep and refreshing sleep in which it had fortunately forgotten +much of the past, a new era dawned and modern thought began. +Immediately men commenced to busy their minds with broader problems +than they had been discussing since the time of the Greek +philosophers. The hand of tradition, however, was heavy on them still. +They dreaded to run counter to authority, and did not dare think +unrestrainedly. Descartes shows us how we can understand things better +if we will imagine a few principles by which it will be easy to +account for things as they are. Then he carefully elaborates these +principles as they occur to him; but he has no sooner done so than he +takes care to add, "Of course, we know the earth was not made in this +way." + +A little later the philosopher, Leibnitz, believed in an orderly +creation that had advanced by regular degrees, and that the lower +animals had thus developed into the higher. He adds interestingly that +there are probably on some other planets animals midway between the +ape and man, but that nature has kindly removed such animals from the +earth in order that man's superiority to the apes should be entirely +beyond question. + +By the middle of the eighteenth century men had begun to think more +fearlessly. The great Emanuel Kant wrote in his younger and less timid +years, "The General History of Nature and Theory of the Heavens." The +great Newton had by his law of gravitation brought order into the +heavens. Kant looked longingly for a greater Newton, who should find a +similar unity in the animal world. He saw the wonderful likenesses +between animals that the anatomist, Buffon, had recently pointed out. +He believed there must somehow be blood relationship between all +animals. He tried hard to conceive of some underlying natural cause by +which all could have come about. As he grew older and his mind became +more cautious he came to think the matter deeper than the human mind +could ever fathom. He gave up the hope and believed the problem of +animal origin and derivation would forever remain insoluble. He +feared there was not in man the power to conceive his own origin. + +If we ever wonder why it took so long before the thought of evolution +should have fully dawned upon the world, the answer is not far to +seek. No student of Natural History in ancient or medieval times had +the faintest conception of the enormous number of animals and of +plants in the world. The old Greek or Roman student of Natural History +gives no evidence of knowing more than a few hundred animals. Men have +named to-day, with systematic Latin names, hundreds of animals for +every one that Pliny ever knew, and he knew more than any other man of +early times of whom record has come to us. + +In early days men who traveled into foreign countries brought back +accounts of what they saw. The whole Natural History of ancient times +was filled with the most absurd and ludicrous stories of all sorts of +things to be seen in distant lands. Sir John Mandeville tells tales +almost as imaginative and quite as amusing as those attributed to +Baron Munchausen. + +Upon the great awakening of the fifteenth century, with its new study +and its wide-ranging travel, an entire change came over the human +mind. Men who journeyed into far countries brought back with them not +only accounts of what they saw, but, so far as might be, the things +themselves. Collections of plants and of such parts of animals as +could be readily preserved soon began to accumulate in every great +center of Europe. It was only a question of time when such +acquisitions must be arranged and classified, but as yet there was no +system by which this could be done. The great Swedish botanist, +Linnæus, who lived in the eighteenth century, first taught us to give +to each animal and plant two Latin names, the first of these to be the +name of the group, known as a genus, to which it belongs, the second +to be the name of that sort, or species, of animal. The cat, for +instance, is _Felis catus_, the lion _Felis leo_, the tiger _Felis +tigris_, and so on. Linnæus then arranged the genera (plural of genus) +into families, and these families into orders and so classified the +animal and plant world as far as he knew it. In his earlier years +Linnæus thought of each species as being utterly apart and distant +from any other. He believed it had been so from the first, each +species having sprung in its complete form from the creative hand of +God. In later life he came to show some evidence of the belief in +development, but his great work is all built on the idea of the entire +fixity of species. + +About this time we find in the writings of Buffon, the French +naturalist, many indications of an idea approaching our modern +conceptions of evolution. He felt sure the pig could not have been a +special creation, because he had four toes, two of which, with all +their bones and their hoofs, are quite useless to him. We now call +these toes "vestigial," and know the pig's ancestors used them, +walking on four toes and not on two, as at present. Buffon believed +there were degenerations as well as developments, and considered the +ape a degenerate man. He conceived these changes to be brought about +by what he called the favors and disfavors of nature. He varied much +in his opinions in various parts of his career and occasionally is +smitten either with conscience or with fear of authority. Then he goes +back and says it is all a mistake and each animal is the product of a +special act on the part of the Creator. + +A little later, in England, Erasmus Darwin, the grandfather of Charles +Darwin, who was subsequently to establish the evolution theory, wrote +a long and elaborate poem called the "Temple of Nature." In this we +find a remarkable prevision of many of the principles which were +afterward to be warmly advocated and disputed during the growth of the +idea of evolution. + + "Hence without parents by spontaneous growth, + Rise the first specks of animated life. + + * * * * * * * + + Thus as successive generations bloom + New powers acquire and larger limbs assume." + +Erasmus Darwin recognized the struggle for existence, but he saw in it +only a check against overcrowding, and not an active factor in the +development as his grandson Charles came to see it. It is possible the +elder Darwin's views might have been taken more seriously had he not +clothed them with the form of verse. In these days it seems quite +ludicrous to think of giving to the world a new scientific concept or +a new phase of philosophy in verse. + +The beginning of the nineteenth century gives us the first really +great contribution to the idea of evolution. Under more favorable +surroundings, this idea would have budded and become the parent stock +of our modern theories. The chill frosts of adverse criticism by those +in authority in science nipped the budding idea and so set it back +that only of late years have men come to realize its strength and +power. The Chevalier de Lamarck, serving in Monaco, was attracted by +its rich flora to the study of botany. Coming later to Paris, he +became acquainted with Buffon and was led by him to publish a Flora of +France, using the Linnæan system of classification. He was appointed +to the chair of zoölogy in the Jardin des Plantes, and was given +especial charge of the invertebrate animals, comprising all the +members of the animal kingdom except those with backbones. After +seventeen years of work over these forms, during which he wrote +several books describing them, he finally published the great work on +which his fame depends. This was the "Philosophie Zoölogique." In this +treatise he taught that the animal kingdom is a unit and that all its +members are blood relations; that the members vary with varying +conditions; that this variation results in continued advance. In all +of these points Lamarck is at one with modern thought. His idea of the +method by which the variation comes about has been accepted and +rejected; modified, reaccepted, and again rejected. + +Lamarck's conception of the cause of progress was somewhat as follows: +The desire for any action on the part of an animal leads to efforts to +accomplish that desire. From these efforts came gradually the organ +and its accompanying powers. With every exercise of these powers the +organ and its corresponding function became better developed. Every +gain either in function or in organ was transmitted to those of the +next generation, who were thus enabled to start where their parents +left off. The general environment constantly gave the stimuli that led +to the adaptive changes. + +American zoölogists have been especially inclined toward Lamarck's +ideas. Until Weissmann startled the scientific world with his sharp +denial of the possibility of transmitting to offspring any growth +acquired by the parents, all seemed well. There is a tendency now to +insist once more that slowly and gradually, in some perhaps as yet +unexplained way, external factors do influence even egg cells, and +gradually acquired characters do reappear in the offspring. + +The blighting setback these views suffered came from the criticisms of +Baron Cuvier. This genuinely remarkable man had built up the study of +comparative anatomy. To him students flocked from all sides. Among +these one of the most brilliant was Agassiz, the Swiss naturalist, who +later came to this country, filled with Cuvier's ideas. This great +teacher believed that species are fixed. He knew better than any man +of his times the wonderful similarity in structure between animals of +a given class. He attributed this not to any real blood relationship +between the animals. They were alike because they had been made by the +same Creator. This great Artificer worked along four main lines, and +hence animals could be divided into four groups. Many who have studied +text books on zoölogy written in this country by Agassiz and his +followers will remember the four classes--Radiates, Articulates, +Mollusks, and Vertebrates. Agassiz was such a wonderful teacher and so +genial and so lovable a man that his opposition to evolution held back +the advance of the Darwinian idea in America as Cuvier's influence +had held back the Lamarckian idea in Europe. For the brilliant Cuvier +simply laughed before his students at each "new folly" of Buffon and +of Lamarck. Under this ridicule the influence of both men withered and +died. + +A little later the great poet, Goethe, turned his attention to the +problem of evolution, giving an interesting account of the +metamorphoses of plants. He declared, also, that the human skull is a +continuation of the backbones of the neck, and that these bones have +been transformed into the present skull. But his great genius as a +poet drew his attention into other fields. Haeckel points out that if +Goethe had known Lamarck's work his genius would have gained for the +"Philosophie Zoölogique" the interest and respect of the reading +world. But Cuvier laughed it out of court, and only in comparatively +modern times, since Darwin's work has set the world thinking anew, is +Lamarck's career recognized at its true value. Lamarck should have +been the founder of the evolution theory. But the time was not quite +ripe, and it remained for Charles Darwin to announce his idea, +sustained and fortified by years of careful observation and thoughtful +reflection. + + + + +CHAPTER II + +DARWIN AND WALLACE + + +We have seen in the last chapter that whenever men have actively +thought they have attempted to explain the origin of plants and +animals as well as of themselves. No one who wrote previous to the +time of Charles Darwin had expressed any idea concerning this matter +with force enough to convince any large portion of the thinking world. +If Lamarck had fallen on better times, if the great Cuvier had not +laughed him to scorn, if Goethe had found him out and made him known +to the world, evolution might have come into its own sooner. None of +these conditions arose, and it remained for Charles Darwin to give to +the world in clear and cogent form the thought of evolution. He +gathered so much material before he expressed his opinions, and looked +at the matter from so many sides that, when he published his results, +he had foreseen most of the objections which were subsequently to +arise in opposition to his announcement. Charles Darwin is recognized +to-day as the father of the evolutionary movement. + +It has been sometimes said in recent years that Darwinism is dead, and +there is a sense in which this is true. Unmodified and unassisted +natural selection is not to-day considered by most scientists a +sufficient agent for producing evolution. But everyone connected with +the subject acknowledges Darwin as the master, and says that it was +his work which converted the world to a belief in evolution. We can +have no better preparation for an intelligent understanding of this +subject than to consider carefully the life of this remarkable man and +the circumstances under which he came to his epoch-making conclusions. + +Evolution has taught us to attempt as far as may be to account for man +on the basis of his heredity or of his environment. It is interesting +to note that both of these factors in Darwin's case were entirely +favorable. In the latter part of the eighteenth century Erasmus Darwin +had given to the world an astonishing poem in which he anticipated not +a little of the thought which his more famous grandson was to make so +widely known. Josiah Wedgwood had learned to make for England her most +famous pottery, no quality of which was more widely recognized than +the sterling patience with which it was made. Erasmus Darwin, with his +scientific proclivities, and Josiah Wedgwood, with his sturdy common +sense and patient workmanship, united to give Charles Darwin his +inherited tastes, for he was a grandson of both. Born in 1809, on the +banks of the Severn in England, Charles Darwin was the delicate son of +a practicing physician of modest but sufficient means. Owing to his +lack of early vigor, Darwin spent much time in the open air, and in +his excursions about his home was chiefly interested in collecting +beetles. This taste, which lasted through all his young manhood, is +the one early indication of the traits that were later to develop. At +first in the day-school and later in the preparatory school Charles +Darwin was anything but a satisfactory student. Even a kindly desire +later to make the most of him makes it impossible to find traces of +any especial fondness for earnest study. He himself believed his +education to have been nearly useless, although he doubtless +under-estimated its value. At the age of sixteen he went to Edinburgh +at his father's desire, to study medicine. The sight of the +dissecting-room nauseated him completely, and he refused to continue +working in it. Later an operation which he witnessed in a clinic at +the hospital sickened him so thoroughly that he declined to attend +further operations. It became evident that the young man was not +adapted to the life of a physician. The next move was to educate him +for the church, and for this purpose, at the age of nineteen, he went +to Cambridge. Here it soon appeared that he was no better adapted to +the ministry than he was to the practice of medicine, and his +university career went on in very desultory fashion. Most of his work +was distinctly neglected, but two of the men he met there were to +influence largely his future life. Henslow, the botanist, was +unusually fond, for a professor in those days, of work in the field. +Charles Darwin's tastes coincided with those of Henslow, with whom he +formed an intimate friendship. He was always welcomed as a companion +on the field trips. Though he studied little of botany in the +classroom or laboratory, he was constantly with Henslow or with +Sedgwick in the field. Sedgwick was the professor of geology, and of +him Darwin was particularly fond, and under him did much the largest +amount of his study. When he came up for graduation he ranked tenth of +those who "did not go in for honors," a not very remarkable class +standing. He was still required to put in two years of residence, and +during this interval he spent most of his time with Sedgwick in the +study of geology in the field. Returning to his home after a +geological trip into Wales, Darwin found awaiting him a letter from +Henslow, offering him an appointment that opened to his ardent mind +the door to a career after his own heart. + +The British nation, being the greatest commercial nation of the globe, +has the greatest need for accurate charts of all the seas. Frequently +she has sent out great charting expeditions to various parts of the +world. One of these was to go out in Her Majesty's ship, _Beagle_, for +a voyage around the world. Captain Fitzroy was in command, and he was +especially commissioned to map the coast of South America from La +Plata to Cape Horn and up the western side. In addition to this work, +by carrying a set of accurate chronometers, he was to check up the +longitude of the various ports to be visited in this circumnavigation +of the globe. It was customary on such expeditions to carry a young +man whose duty it was to study the natural history of the countries +visited on the trip. The salary of such a naturalist was so small that +an experienced man could scarcely afford to take the place. Therefore +the appointment usually went to a man rather of promise than of +achievement. Through Henslow's influence, Charles Darwin was offered +this position in 1831. Darwin hastened to obtain his father's +permission, but the elder Darwin at first declined to consider the +matter. He felt that his son had not made such use of his time at the +university as warranted the hope that much could be expected of such a +journey. He believed it necessary that Charles should have some means +of earning an adequate living before he could think of devoting his +time to science. Charles found an efficient advocate in the person of +his uncle, Josiah Wedgwood, Jr. Together they persuaded the father of +the propriety of giving to Charles this opportunity to follow out his +real tastes and ambitions. Accordingly, at the age of twenty-two, we +find him embarked on a journey around the world. In the cabin of the +_Beagle_ he had abundant time, in his long sail across the Atlantic, +to read the two volumes of Lyell's "Elements of Geology," which +Henslow had handed him, with the suggestion that he read it, but on no +account believe it. Filled with the love of geology as Darwin was, +this epoch-making book was exactly the stimulus needed. Lyell had just +begun to persuade the world that to understand the past we must study +the present. In the forces now at work he saw cause enough to account +for all the history of the past of the earth. + +There is little doubt that this book was one of the most potent +factors in determining the bent of Darwin's mind. His entire +educational experience had failed to appeal to him. It is fortunate, +we now know, that this was the case. If the university course of the +time had really seized him it would have made but one more student +like hundreds it was turning out each year. For most of us this is the +happy event. Now and then comes the rare spirit to whom all of this +fails to appeal because he is ready for something better. Such was the +spirit of Charles Darwin. He started on his journey with a mind +singularly free from prepossessions. In the long hours of this sailing +voyage across the Atlantic Ocean Darwin had time to read and ponder +Lyell's weighty words. By the time he reached the Brazilian shore he +was filled with Lyell's conception that the present is the child of +the past, developing out of it in orderly sequence. Lyell expressly +denied that this is true of the animal and plant world. He applied it +only to the face of the earth, with its mountains of uplift and its +valleys of erosion. But the underlying principle of an orderly +development under the action of natural causes was there. In Darwin's +mind this at once found acceptance, and was destined to a fruition its +author had expressly disclaimed. + +The narrative of this voyage, as subsequently written, describes the +islands visited by the _Beagle_ in crossing the Atlantic Ocean. The +contrast between the simple and general interest in these islands and +the care with which Darwin described the Galapagos and the Keeling +Atoll visited later in the voyage are speaking evidence of the rapid +development going on in the mind of the young naturalist. + +Reaching the shore of South America, Darwin first turns to its +geology. But before long the animal life attracts his attention. In +the Brazilian forest Darwin had his first experience of the wealth of +animal and plant life in the tropics, and, like all naturalists, he +was very enthusiastic over it. Among the animals that particularly +attracted his attention was the sloth, a peculiar creature climbing +slowly about the trees, small of size and sluggish of habit. Another +animal that interested him greatly was the little armadillo with its +interesting habit of curling up in its plated skin. + +Captain Fitzroy soon finished what work he was required to do in this +neighborhood, and Darwin was called back to the _Beagle_ to continue +his voyage. When they arrived at the mouth of La Plata their most +serious work began. Here there was much tedious charting for Fitzroy, +and Darwin could now leave the vessel for a lengthy trip on shore. +This was doubly welcome. Seasickness was nearly constant with Darwin +while on this entire voyage and every opportunity to work on land was +eagerly seized. This region, too, was rich in objects of interest and +in strange people. While exploring the pampas, beyond Buenos Ayres, +Darwin came across the skeletons of the great mammals some of which +Cuvier had previously described. He studied these bones with much +care, and recognized at once in the megatherium a great similarity in +structure to the sloth he had seen in Brazil. The enormous skeletons +of the glyptodons struck him also as strangely similar to that of the +armadillo. One evening, seated alone in the broad expanse of the +pampas, the idea suddenly swept over him, stimulated, of course, by +his study of Lyell: "Can it be that the little armadillo and the sloth +of to-day are the degenerate descendants of the enormous megatherium +and glyptodon of the past?" But his mind was not yet ready to accept +so bold an idea and he swept it aside. + +The people of this wild neighborhood interested Darwin very greatly, +and he describes them with care. In this connection a charming trait +of Darwin's character comes beautifully in evidence. The absolute +purity of his mind, his utter freedom from grossness, shows clearly in +his account of the first really semi-civilized people he had ever +seen. + +A little later, while exploring Patagonia, Darwin noticed the +terrace-like formation of that desolate country. A flat near the sea +was succeeded by a rapid rise, then came another flat. Three of these +terraces in succession stretch back toward the Andes. At the base of +the high terraces Darwin found marine shells, largely similar to those +of the ocean beach so many miles to the east. His study of Lyell led +him to suspect at once that this portion of South America had been +raised in successive stages out of the bed of the Pacific. When they +passed around Cape Horn and up the western coast he hunted for +similar beach marks on the sheer western face of the Andes, and found +them without difficulty, confirming his idea of the recent rise of +this end of the Andean chain. + +The _Beagle_ continued its voyage up the western coast of South +America until it reached Peru. Once more the abundance of tropical +life is under Darwin's eyes, but now it is the life of an entirely +different section. The dry climate of Peru furnished him with an +environment distinctly unlike that of the moist Brazilian forest. He +collects now with avidity, gathering especially insects and birds. +Then the ship turned its prow westward across the Pacific, only to +stop five hundred miles out at the Galapagos Islands. This little +group he studied intensely, collecting large numbers of insects and +birds. He had not worked over his collection long before he realized +that each island in the group had peculiarities which marked its +animals from those of any other island. Whenever two islands were +close together in the group the differences in their fauna were found +to be comparatively slight. If, however, he examined the animals from +two islands lying at opposite ends of the group, the differences were +always considerably greater. There was, however, a strong general +resemblance among them all and a distant though not so strong +resemblance to the corresponding animals of the Peruvian coast. On +leaving the Galapagos group, Charles Darwin writes in his diary the +suggestive observation that this little group of rocky islands seems +to be one of the greatest centers of creative activity. It was this +interesting resemblance of the animals of these islands to each other +and to those of the Peruvian coast that finally persuaded Darwin that +they were all related and were all descended from those of Peru. For +the rest of his life, with an intensity which increased with each +year, Darwin persisted in a patient search for the possible agencies +by which such change could have been brought about. The problem, +however, was temporarily eclipsed by a pressing geological question +aroused by his visit to the Keeling Atoll. Here his investigation of +coral reef formation absolutely captivated him. In the case of most +coral islands in the Pacific Ocean the reef exists as a circle of +coral enclosing a lagoon of water. In the center of this lagoon stands +commonly a rocky island. It is plain that this is the foundation on +which the coral built. But, in the case of the Atoll, the coral ring +was present and so was the internal lagoon, but there was no rocky +island. The key to the solution came with an interesting discovery. +Darwin began to put down a grappling iron on the outer side of the +reef and to drag up coral. The farther away from the reef he went the +deeper was the water from whose bottom he pulled the coral. What at +first puzzled him was the fact that so long as he dragged up his coral +from depths of a hundred feet or less the coral was alive. Whenever he +went to depths of much more than a hundred feet, his coral was always +dead, though he was evidently pulling it from situations in which it +had grown. Then Darwin remembered the rising Andes, lifting themselves +out of the bed of the Pacific. Here was the correlated movement. The +bottom of the ocean here was sinking. As it sank it dragged down the +corals with it. But the descent was so slow that new corals could +build on top of the others fast enough to keep the reef up to the +surface of the water. At the rate of growth of coral, this would seem +to mean that the bottom could be sinking at a rate of only a few feet +a century. But while the reef could keep up to the surface, the rocky +island must slowly sink. Darwin inferred that there must be a rocky +summit within the lagoon, below the surface of the water. A little +sounding soon discovered this island, and the verification of Darwin's +theory of coral reef formation was at hand. The description of this +Atoll and of his theory of its formation won for Darwin the esteem of +geologists when he later presented it in book form. + +The voyage was continued around the Cape of Good Hope. Pursuing the +usual course of sailing vessels, the _Beagle_ touched once more at +Brazil, returning home to England in 1836, after an absence of five +years. Charles Darwin himself believed this trip to have been both his +education and his opportunity. He had started on it a rather careless +and indifferent student. He returned from it the most painstaking and +patient naturalist the world has ever known. His father, who had +hardly consented to his going because he believed him not stable +enough to be intrusted to his own devices for so long a period, was +profoundly moved at the sight of him on his return. Believing in +phrenology, as did many of the physicians of his time, his father +turned to his mother and said, "Look at the shape of his head; it is +quite altered"; which, translated into the language of to-day, would +read, "How wonderfully the young man has developed." + +A part of Charles Darwin's duty to the British Government was to write +a narrative of the voyage, and this account of his trip upon the +_Beagle_ is one of the great classics of travel in the English +language. It won the confidence and respect of a wide circle of +readers. In his next book he published his observations made at the +Keeling Atoll and announced his theory of the formation of coral +islands. This was a distinctly scientific investigation, and it won +such immediate favor among geologists as to increase materially the +young man's reputation. No one man is ever widely enough acquainted +with the animal world to classify all the specimens gathered on such +an expedition. In accordance with custom, Darwin began distributing +his collections among specialists. Each of these was to identify and +describe, to name, if necessary, the kind of material he knew best. +Among others, Darwin had a considerable collection of barnacles +gathered from boats and wharves in all parts of the world. As he could +find no one sufficiently acquainted with these creatures to classify +them he decided reluctantly to work them up himself. For about eight +years much of his spare time was given to this painfully exacting +work. He expresses himself as fearing it was a waste of time. Few +systematic workers will agree with him. He did his work so well that +it has been unnecessary for anyone to do it again. In addition it +gained him the esteem of a new circle of scientists and that a +decidedly exclusive circle. + +The publication of these books did much for Darwin. His narrative of +the voyage gained the good will of cultured England in general. The +book on coral reefs won the geologists. His "Manual of the +Cirrhipedia" (as the barnacle book was called) secured the attention +of systematic zoölogists. The time was not far distant when he would +need every aid possible toward gaining and keeping the regard of men; +for he was to promulgate a theory that would arouse the bitterest +opposition and the keenest scorn. + +All the while Darwin was working on these books his mind was quietly +busying itself with what he called the species question. The more he +studied the material collected on his long tour, the more confident he +became that the animals of the present are the altered descendants of +the animals of the past. He tried patiently to work out every +conceivable hypothesis to see whether he could account for the +alteration. He felt quite sure animals changed, but how they changed, +and why, he could not for a long time conceive. He knew that gardeners +were constantly producing new varieties of plants, and that animals of +various breeds were clearly the descendants of other and familiar +varieties. Accordingly he began to study the methods of animal and +plant breeders, to visit their farms, to open correspondence with them +and read all their trade journals, to undertake experiments in the +breeding of plants. The longer he worked the more confident he became +of the reality of the change; but for a long time no glimmer of the +cause by which it could be brought about came to his mind. In 1838 he +came across a book by Malthus called "An Essay on Population," in +which the author shows that, whereas man increases by a geometric +ratio, he cannot hope to increase his food supply in more than an +arithmetic ratio. That is, while the food might increase like the +series 2-4-6-8-10, the population would increase like the series +2-4-8-16-32. On this basis it is only a question of time when the +earth will be too full of people for it to be possible for the food to +sustain them. Malthus added many observations and suggestions, but +this is as much of the book as interests us in this connection. Here +was the idea that suggested to Darwin his agency for producing the +change of the animals of the past into those of the present. + +The number of animals of any particular species remains practically +the same. There may be a few more one year, and a few less another, +but on the average, year by year, the number of toads, the number of +blacksnakes, the number of field mice, remains sensibly the same. +Sometimes the rise of man brings an end to the wild population, and so +in the past animals have dropped out of the race. Yet in the long run +and for a considerable time the number of any species is constant. But +each animal produces offspring in quantities sufficient to far more +than replace himself as he dies out. In other words, animals increase +not by addition but by multiplication. Too many are born for all of +them to live. What becomes of the great mass of them? The answer is +they die; most of them die young. Only a few fortunate individuals, +favored by being a little stronger, a little more cunning, a little +more attractively colored than their mates, survive to carry on the +race. + +The skillful gardener, looking over his flowers, finds a plant of more +than ordinary beauty and thrift of growth. When it comes to maturity +he keeps its seeds separate from those of the rest and next year +plants them by themselves. As they come up he weeds out all unthrifty +plants, only allowing the strongest to come to maturity. As they break +into bloom he plucks away all whose flowers do not come up to the high +standard he has set for himself. After a while he has but a few plants +left, but these are the thriftiest and bear the most beautiful +flowers. Again he allows these to mature and selects the seed of the +very finest. Next year the process is repeated. After a few +generations, usually three if the man is skillful enough, he has a +definite strain of flowers that will thereafter come true. This is the +process of artificial selection as carried on by man. + +Darwin saw that Nature is constantly carrying on a similar process. +She produces seeds enough on almost any plant to clothe the world in a +few years if all of them could fall into proper ground and thrive like +their parents. A friend of mine found a mullein stalk that bore more +than seven hundred seed pods and averaged more than nine hundred seeds +to the pod, a total of more than six hundred and thirty thousand +seeds. If each of these could find lodgment on a plot eighteen inches +square, produce a similar number of seeds and plant them all, the +result would be overwhelming. The fourth generation would cover land +and sea, from pole to pole, one hundred layers deep. But there is no +such danger. Year by year the mulleins hold their own and no more. Any +particular field may have more or less, but in the long run the +average for a district is about the same. Some of the seeds are poor +and thin. These scarcely sprout. Others spring up into thin-skinned +plants, and the first frost nips them. Still others lack the woolly +coating in its finest abundance, and the browsing animals eat these. +Others lack power to put out a wide-ranging root supply and the first +drought kills these. Still others fail to send up a vigorous stem and +the passing animal knocks them over and they die. Of the few that are +still surviving, some produce such small and inconspicuous blossoms +that the insects scarcely see them, and they go unfertilized. In the +end only the aristocrats of the group are left, aristocrats in the +best sense of the word. These are strong, thrifty, and beautiful, and +are provided with every defense known to the mullein world. From these +the mulleins of the next generation will spring. Again Nature will +select the best of these, by a repetition of the same process. Thus +year by year the stock is improved. Any new feature that is favorable +helps its possessor to survive, and, if happily mated, will show +itself after a while in the entire group. This, in brief, is the +underlying idea of Natural Selection, as Darwin conceived it. + +In 1842, at Lyell's suggestion, Darwin wrote a short sketch of his +ideas which he, two years later, expanded into a somewhat larger +account. The manuscript of these early views of the theory was +completely lost and has only been recovered within the last few years. +It was recently published under the editorship of Charles Darwin's +son, Francis. It is astonishing to see how clearly the first short +sketch states the underlying conception which all of Darwin's +subsequent work amplifies. Hooker was constantly urging Darwin to +write out his whole theory in the form of a book, and Darwin had begun +to do so in 1856. + +Meanwhile, down in the Moluccas, Alfred Russell Wallace had been lying +sick of a fever contracted during his exploring expedition in that +neighborhood. He had been studying the distribution of the animal life +of the Malay Archipelago. Overcome by sickness, as he lay in bed, he +began to think over a book which he had read not long before, "Malthus +on Population." Wallace had been pondering on the question of the +origin of the animals of the Malay Archipelago. He had not the +faintest knowledge of what Darwin was doing, but was influenced, of +course, like Darwin, by what he read in Malthus. Interesting to +relate, he had come to exactly the same conclusions, writing his +opinions in the form of an essay. By the strangest sort of +coincidence, he sent this essay to Charles Darwin, asking him to read +it, and, if he thought it was not altogether too foolish, to send it +to Lyell for publication by the Linnæan Society. Darwin read with +utter astonishment this essay containing views so absolutely like +those that had come to him from his own long series of observations +and reflections. With uncommon magnanimity his first impulse was to +withhold his own publication entirely, but to this Lyell and Hooker +would not for a moment consent. They were determined that Darwin +should give them his long series of notebooks as evidence of the +independence of his work and that he present to the Linnæan Society, +simultaneously with Wallace's paper, one of his own upon the same +subject. In this manly form both essays were read at the next meeting +of the society. The joint papers provoked instant discussion and +prompt opposition. The world at large scarcely admitted a possible +doubt of the fixity of species. Men generally believed the idea to be +absolutely irreconcilable with their religious faith. Any question of +the fact that the species of to-day exist practically as they had been +handed down to the earth in the beginning by the Creator himself +seemed to most men a direct blow at religion. At this time a very +large number of natural scientists were clergymen, hence the +opposition had abundant and influential support. The storm grew +fiercer and more widespread. The publication in 1859 of Darwin's great +book on "The Origin of Species by Means of Natural Selection or the +Preservation of Favored Races in the Struggle for Life" added fuel to +the flame. + +In 1860 the British Association met in Oxford, and Bishop Wilberforce, +the retiring president, in accordance with the custom of the society, +gave a summary of the advance of science, especially during the +preceding year. Everyone knew perfectly that the bishop would deal +with the species question, and that he would handle it severely. +Darwin was prevented by his usual ill health from being present at +this meeting, but Huxley was there to see that their side of the +question received proper attention. The bishop made a lengthy address, +in the major portion of which he brought forward entirely worthy +objections to Darwin's theories. Toward its close his feelings +overmastered him and he departed from his manuscript and unburdened +his mind. The lack of stenographers in those days and the tenseness +of the moment, which made everyone forget to take down what was said, +make it impossible to tell exactly what happened. It seems that Bishop +Wilberforce, appealing to the prejudices of his audience, said, in +language that now seems ludicrous but then was terribly bitter: +"However, any of us might be willing to consider ourselves descended +from an ape upon his father's side, no one would so demean his +mother's memory as to imagine that she could possibly have shared in +this descent." Huxley, who had waited patiently for the close of the +bishop's address, saw immediately the fatal mistake. Turning to his +companion beside him, he said, "The Lord has delivered the Philistine +into my hands," and, rising, he hurled back at the bishop the +indignant reply, "I should far rather owe my origin to an ape than I +would owe it to a man who would use great gifts to obscure the truth." +The bishop had made the mistake, and the struggle was on. Year by year +it raged. One by one the scientists, first of England, and then of +Germany, took their stand by Darwin. Huxley in England and Haeckel in +Germany were the foremost advocates of the Darwinian idea. Long and +fiercely the battle raged; slowly and gradually men began to see that, +instead of undermining religion, the idea of evolution uplifted +creation and made it not a strange happening in the distant past, but +a divine activity through all time. But the battle had by no means +subsided when one day came the sad news that Darwin's heart, so long +feeble, so serious a hindrance to his work, had beaten its last on +April 19, 1882. + +His own people wished to bury Darwin quietly at his home in Down, but +Darwin now belonged to the nation. A petition signed by many public +men was sent to the Dean of Westminster, asking that his body might be +granted burial in the Abbey. Probably no greater honor can come to man +to-day, and fortunately Dean Bradbury was broad-minded enough to +acquiesce. So it came to pass that the church that had so long +believed him her enemy, that had first so bitterly fought him, came at +length to see that he added a new dignity and worth to her faith, and +took him to her bosom. Darwin's body lies buried in the Abbey. + +In all the glorious company of immortal dead whose earthly frames are +gathered in England's great mausoleum, there is no other one who has +done so much to modify the mind of thinking man. + + + + +CHAPTER III + +THE UNDERLYING IDEA + + +We have seen in the preceding chapters how the idea of evolution +worked its way through the minds of men. Man after man got a glimpse +of the idea, even among the ancient philosophers. But no one could +speak convincingly on the subject before modern times, when a wider +acquaintance with the animal world gave a body of facts on which it +was safe to base conclusions. Even then the idea eluded men, until +there came a worker trained by a long voyage around the world in which +he had nothing to do except to study nature. He finally gathered in +his mind material sufficient to convince himself not only of the truth +of evolution but of the process by which this evolution was brought +about. Every scientific principle is simple in its basal idea. In +actual life the action of the principle may be so bound up with others +as to need a skillful mind for its detection. But under all the +complexities and modifications, like a silver thread woven into a +cloth, runs the basal idea. Until a master has detected it the +presence of it may be unsuspected. But once discovered and expounded, +thereafter anyone may follow out its workings. So it is with the +Darwinian idea of selection. It waited long for a discoverer, but, +once found, we cannot but wonder why men did not see it earlier, it is +so simple. + +Mr. Darwin's mind, while slow and cautious, had a wonderful +perseverance. When he had finished his work he had not only given a +clear account of the process of evolution, but he had foreseen almost +all the valid objections that were afterward to be brought against his +theory. Some of them he had explained quite fully; of others he +indicated a possible explanation; of still other questions he +confessed that as yet they were not plain. But the whole theory is so +simple in its fundamental ideas that it has completely revolutionized +the whole aspect of modern biology and, indeed, of modern thinking in +many lines. + +There are four underlying conceptions, each simple in itself, which +must be clearly perceived before one can understand Mr. Darwin's +theory of "Natural Selection." The first of these is known under the +name of Heredity. It is a matter of common observation that every +animal or plant produces offspring after its own kind. Under no +conditions would we expect a duck to lay an egg from which could hatch +anything but a duck. No Plymouth Rock chicken mated with another of +her own kind will ever lay an egg that will produce a Rhode Island +Red. We may believe that the dog has descended from some form of wolf, +but it is not meant that at any particular time in the past any wolf +mated with a wolf ever produced pups that were anything but wolves. + +Why this should be so is one of the most profound problems of biology. +Nothing but the fact that the process has gone on under our eyes for +so long a time could blind us to its marvelous character. To open the +egg of a chicken and examine it by the most refined methods known to +science is to find in it absolutely nothing that could be by the +widest stretch of the imagination considered anything like a chicken. +The biologist who has examined such eggs before and knows them in all +stages of the process may recognize in an egg which had been incubated +for a short time something which his previous experience tells him +will become a chicken. But it has not the faintest resemblance to a +chicken until later in its development. In early spring one may gather +pond snails from any country stream and place them in an aquarium. The +change from the cold water on the outside to the warmer water of the +aquarium and the temperate climate of the room hastens the process +which in the stream would not take place until later. In a short time +one may find fastened to the glass side of the aquarium the little +mass of transparent jelly which surrounds and protects the delicate +eggs of these creatures. Fastened as they are it is easy to direct a +magnifying glass so as to observe the change which goes on within +these transparent eggs. It is even possible to apply a microscope in +such a way as to watch the transformation under the low power of the +glass. At first the eggs are as clear as water, having at the center a +slightly yellowish spot. This central mass divides and subdivides +until the separated sections grow so small and numerous as to lose +individuality. Then the mass begins to press out here and dent in +there. After a little while a double line of fine, hairlike +projections runs around the creature. These hairs wave in such fashion +as to make the embryo snail revolve slowly in its egg. A little later +and swellings become more pronounced over the surface. One side +flattens; the rotary motion stops; eyes appear at the front of the +animal; a hump on the back begins to be covered with a shell, and the +little creatures, pushing from the jelly, start their life journey on +the side of the aquarium. Why did it happen? How did it happen? Here +we have seen creation at work. Here surely the hand of the Creator is +working in the only sense in which the Creator may be properly said to +have a hand. How the history of the substance out of which the egg was +produced provides for the future development of that egg no man has +yet clearly said. This is not to say that we shall never know, still +less is it to say that this can never be known. Ralph Waldo Emerson +has said that there is no question propounded by the order of nature +which the order of nature will not at some time solve. If he is right, +and I believe he is, we shall at some time know how it is that this +egg produces this snail. But, as I said before, nothing but the +frequency with which the process goes on under our eyes could possibly +blind us to the marvel of it. + +The regularity with which each animal reproduces its kind is no more +surprising than the faithfulness of that reproduction. Some of our +birds have wonderful markings on their plumage. It is astonishing to +see with what fidelity the feather of a bird may reproduce the +corresponding feather of its parent. It will occur to everyone how, in +the human family to which he belongs, there is some little peculiarity +which, while not appearing in every member of the family, when it does +appear is remarkably uniform. It may be only the droop of an eyelid, +it may be a tendency to lift one side of the lip more than the other, +it may be the peculiar shape of a certain tooth in the set, and yet +when it appears it comes with astonishing similarity in all who +possess it. So much for the principle of Heredity. + +The second great underlying idea is known by the name of Variation. We +have just been dwelling on the regularity with which parents produce +offspring like themselves. We must now draw attention to the fact +that, while it is true animals must absolutely belong to the same +genus or species, even to the same variety, none the less no animal is +exactly like his parents. Furthermore, in a group of animals produced +at the same time from the same parent each one will have at least some +small point in which he differs from every other one in the group. Two +animals may look alike at first to the undiscerning eye, but a keen +analysis of the measurements of the various parts of their bodies will +show distinct differences. This is quite as true among lower animals. +A toad may lay a double string of four hundred eggs which may be +fertilized by the same male at the same time. These eggs may develop +into tadpoles in the same pool not over a foot square. Within a few +weeks these little toads may have gained their legs, lost their tails, +and all may have left the water and taken to the ground upon the same +day. Already the careful observer will notice differences among them. +Some are larger than others, having grown more rapidly even though +their surroundings were exactly the same; others are more skillful in +their peculiar method of throwing the tongue at an insect they wish to +catch. Still others will be differently colored. They might be +arranged to show a considerable gradation between the lightest and the +darkest of the group, though there may not be anywhere in the row a +considerable gap. It is variation in animals of the same parentage and +same surroundings which in the mind of Mr. Darwin made evolution +possible. He always favored the idea that it was the continuous +accumulation of these small variations that finally produced the +profound changes which mark the new species. He admitted the +possibility of the occasional appearance of those more distinct leaps +in variation on which the present school of mutationists so strongly +insists; but he believed them to be less influential, in the general +trend of evolution, than the slower but much more frequent variations. + +One of the most complicated and perplexing problems in the biology of +to-day is the question of the origin of these variations. It is quite +as hard to understand as is the method by which animals produce their +own kind. No problem is being more earnestly studied. Suppositions we +have in considerable number, and two of these at least may reasonably +be mentioned. We will consider first the less certain theory. There is +nothing in the egg that in the remotest degree resembles its parent. +The old idea that every acorn had in it a miniature oak which only +needed to unfold itself, or that the hen's egg had within it a +miniature chick which only needed the warming process in order to make +it evident, could not possibly survive the invention of the +microscope. We may not, and we certainly do not, know everything that +is in one of these eggs, but we do know most certainly that what is +there has no resemblance to what it will be in time. The biologist +finds in the nucleus or central core of every growing and reproducing +cell certain minute bodies which Weissmann believes do much to +determine the growth of the rest of the cell. He believes also that +there are many more such "determinants" than are necessary for the +reproduction of the cell. Each of these determinants may be fitted to +produce slightly different results, but what decides which of them +shall have its own way is quite uncertain. It may be that one +determinant happens to be more favorably placed than others in the +cell and that it has consequently secured more of the nourishment that +comes to the cell in the blood of its parent. If this is true it would +certainly be favored in the competition. We are becoming quite certain +that whatever variations arise really start in the egg. The simplest +conception as to the cause of variation would seem to be varied +experience. One man trains his brain, another his hand; and in each +case the organ so trained develops. But science is strongly of the +mind that such influence does not reach the next generation. + +A musician may have taught his fingers to be nimble; may have given +them speed of motion and precision in their action. No child of his +born after he acquired this wonderful facility of execution is any +more likely to be a skilled musician than a child born before he had +ever practiced enough to be anything more than a crude performer. +Science is nearly certain that his children are just as likely to be +talented along musical lines if he himself never had become a +musician, simply because he had it in him to be a musician. In other +words, they may inherit the talent which he developed, but they +inherited it not because he developed it, but because it was in him to +be developed. This is in accordance with the famous principle that +there is no inheritance of acquired characters. We shall touch this +question a little more fully in a later chapter, in speaking of the +development of the evolution theory since Darwin's time. + +If we are right in this matter, and we certainly are nearly right, +variation must take place for the most part in the germ. These +variations may not show until the animal has grown up, but they must +have taken place among the determinants in the germ cell or they would +not reappear in subsequent generations. + +There is another process by which new variations may arise and which +is more easily understood. It is the method of double parentage. The +Barred Plymouth Rock chicken had its origin in such a double ancestry. +The one parent was a Black Java whose color has disappeared entirely +in the cross, but whose single comb with its few large points comes +out clearly in the newly produced fowl. The other parent was a Barred +Dominique. It is to this parent that the Plymouth Rock owes the +interesting cross markings on its feathers. The comb on the head of +the Barred Dominique is of the type known as the rose-comb, having +many rows of slight projections. This has completely disappeared from +the Plymouth Rock fowls. I am told that the skilled chicken fancier +can tell, concerning many points in this fowl, to which of the crossed +ancestors each quality is due. To a certain extent it is undoubtedly +true that here we have the secret of the origin of many of those +interesting people whom we are pleased to call geniuses. They may not +possess any qualities not clearly discernible in various of their near +ancestors, but in them we find what we, for the lack of a better +understanding, call chance combination in one individual of the finer +qualities of many ancestors, and this individual is so placed in life +as to have these qualities developed and strengthened. + +Charles Darwin, humanly speaking, may be accounted for as the happy +combination of a double heredity and a favorable environment. He +inherited the scientific inclinations of his grandfather, Erasmus +Darwin, and the patient, sturdy honesty of his other grandfather, +Josiah Wedgwood. These developed under the stimulus of the long +five-year voyage, face to face with the world of nature. This happy +complex produced the master biologist. To believe that he came about +purely by chance requires a great stretch of the imagination. "There's +a divinity that shapes our ends." + +We have endeavored to make clear two of the basal ideas underlying +evolution. One of these is responsible for the continued production of +animals or plants of the same kind, preventing the world from becoming +a wild kaleidoscopic and fantastic dream. Heredity is the conservative +force of nature. The other idea underlies the development of new +departures which keep the world from being a dull, dead, unending +repetition of the same monotonous material. Variation is the +progressive tendency in nature. + +The third basal idea is that of Multiplication. Animals and plants +multiply; they do not simply increase, they increase in a geometrical +ratio. Anyone who has worked out one of these geometrical ratios knows +how wondrously they mount up. There is an old familiar story of the +blacksmith who asked the price at which the stranger would sell the +horse he was shoeing. The owner of the horse replied that, if the +blacksmith would give him one penny for the first nail he drove into +the shoe, two for the second, four for the third, and so on, he might +have the horse. No hundred horses in the world taken together have +ever brought such a price as the blacksmith would have had to pay for +the animal on which he was working. This is no circumstance to the +awful story of what would happen to the earth if any animal could +multiply unrestricted. The usual number of eggs laid by a mother robin +for a single brood is four, and she may produce two broods in one +season. This would mean that the original pair had produced eight +offspring, four times their own number. If we can imagine these mating +the next year and producing their kind in the same proportion; and, if +we further suppose that each robin needs a space one hundred feet +square from which to gather his food, we realize the astonishing fact +that in fifteen years every patch one hundred feet square in +Pennsylvania and New York would each have its resident robin, while +the following season would find a robin on every similar patch from +Maine to the Carolinas. Of course this could never happen, this is +simply what would happen if all the robins could grow to maturity and +reproduce at the normal ratio. But the robin is a comparatively slow +producer. + +Our turtles are more prolific. Twenty eggs would probably not be an +unusual number. If we could imagine a turtle to live in the sea and to +produce at this rate; and, if each turtle should need as much room +each way as the robin, and a depth of water equal to its width, before +the robins had spread over New York and Pennsylvania the turtles would +have filled all the seas of the globe. Frogs are even more remarkable +in this respect. Two hundred eggs is not an uncommon number. If each +frog required a space twenty-five feet square on which to subsist, the +entire earth would be more than covered with them within six years. It +is ludicrous to think of such numbers, especially when we realize the +hundreds of thousands of kinds of animals there are in the world, each +of which is also multiplying, and it becomes evident at once that only +an infinitely small proportion of all these creatures can possibly +survive. This, then, is multiplication. + +Here comes into play the fourth basal idea in Mr. Darwin's +explanation. This is the part of Selection. When man produces new +varieties of animals he does it by picking out from his flocks or his +herds such as conform most nearly to his idea of what is desirable. +These he mates, and from their progeny he selects the ones that suit +him best. Generation by generation he gets his domesticated animals to +conform more nearly to the standard of his desires. Natural selection +works in exactly similar fashion. Of all the eggs that are produced by +the animals at large in nature an overwhelming proportion never +develop at all. They dry up, are eaten by their enemies, find no +suitable place or time for development and decay, or are overtaken by +some other calamity. Of the animals which emerge from the remainder an +overwhelming majority come to an untimely end within the first few +days of life. Each has countless enemies which prey upon him, and +these have scarcely devoured him before they themselves become the +prey of some stronger creature. Until Mr. Darwin gave us his elemental +idea it was taken for granted that it was a matter of pure accident +which survived and which yielded in the struggle and cares of life. It +was Darwin who showed us that in this tremendous struggle against +those of his own kind in the search for the same food, against the +elements, in securing a mate, any animals possessing a superiority, +however slight, must have some little advantage in the battle. +Certainly, where so many must utterly fail, only those could possibly +succeed who were well fitted to the circumstances in which they must +live. We used to think animals were destroyed by the "accidents" of +life and no one could foretell accidents. Mr. Darwin made clear that +it was not a question of chance. That which might happen to any +individual animal might be what we, not knowing the process, called +accident, and yet there could be no possible doubt that those who +succeeded were better fitted to battle with life than those who +failed, and that their success was due primarily to their being thus +advantaged. Consequently, if generation by generation the so-called +accidents of life are constantly eliminating the unfit in overwhelming +proportions, not only must the positively unfit disappear, but even +the less fit. The more keen the struggle, the fewer could survive and +the fitter they must be to survive at all. This is Selection. These, +then, are Darwin's four great factors of evolution: Heredity, +Variation, Multiplication, Selection. + +From these it results that the animals and plants naturally become +better adapted to the situation in which they are placed. When, as is +constantly happening through the history of the earth, a change occurs +in the physical geography of any region, when a plain is lifted to be +a plateau, or a mountain chain is submerged until it becomes a row of +small islands, this alteration will produce uncommon hardships among +animals, even though they were well fitted to the old conditions. Any +animal or any species of animals which meets such a calamity has +before it only three possible outcomes of the struggle. First it may +be plastic enough and it may vary enough in the right direction to +adjust itself to the changed conditions. In this case it and a favored +few like it will occupy the altered territory. The second possibility +is that it may migrate while the actual change is going on, thus +remaining in the sort of situation suited to it and its kind. The +third possibility is the one which overtakes a great majority of +animals--they die. Even the entire line dies out, and the strata of +the rocks are filled with the bones, shells, and teeth of such as have +met this fate. They have become extinct. + +Thus far in this chapter we have been considering the influences under +which it is conceivable that animals should advance. There is no +question whatever that there are too many animals born, nor is there +any possible question that a very large proportion of them must +certainly die. There is equally no doubt that every animal produces +after its own kind, and that its offspring, while they resemble it +closely, still vary a little from it and from each other. This fact is +perfectly plain to the most superficial observer who thinks on the +matter at all. It is not so plain, nor is it easily demonstrated, that +all of these acting together do surely, even if slowly, alter the form +and behavior of the animal world. It is difficult to prove that there +is going on under our eyes a steady and real improvement in the +adaptation of the animals and plants around us to the situation in +which they are placed. As far back as man's memory runs they seem to +have been about what they now are; as far even as man's historical +record runs they seem to have suffered no great alteration. The +Egyptian of the old tombs is much like the Egyptian of the same rank +to-day. The African of the tombs has the African features of to-day. +Under such circumstances it is hard to prove that there is a steady +and undoubted advance. For the most part the balance of the animal +world is fairly even, and any species does not ordinarily change +rapidly enough or migrate widely enough to show us its new features. +It is difficult to see the struggle which we are so sure is going on. +The life of animals is so hidden in many of its details that their +joys and sorrows, if such we may call them, scarcely fall under our +observation. Now and then an opportunity comes to see the process of +adaptation work itself out. The struggle for existence begins anew and +is carried on with special vigor, with victory, temporary or +permanent, to one of the participants in the struggle. + +The opportunity to observe such a change is presented in the United +States by the introduction of the so-called English sparrow. This +little creature, received at first with such joy, soon became the +object of an almost bitter hatred on the part of very many people. +This is really due to the fact that this bird is one of nature's +darlings and thoroughly succeeds where it has an even chance. + +The number of birds of any particular species which a region will +support seems to be fairly definite. If a species is especially +protected until it becomes unusually abundant, the removal of the +protection commonly brings it down promptly to its original numbers. +On the other hand, an accident of severe character or a special +persecution may much diminish the number of the species, and still it +will, within a comparatively few years, return to its previous +abundance. + +The inhabitants of Florida who own orange groves will never forget the +winter of '94-5. A bitter cold wave swept along the coast and killed +such large numbers of orange trees as almost to cut Florida out of the +orange market and to open the gate to California, who was eagerly +offering her fruit. This same frost caught the migrating blue birds +and killed them by the thousands. When spring came bird-lovers +throughout the eastern United States found an astonishing scarcity of +these favorites. It was feared that with numbers so small they could +not possibly compete with their enemies and with whatever untoward +circumstances should be their lot. But there is room in this +environment for a definite number of bluebirds. When this number was +suddenly reduced the chances to make a bluebird's living were so +wondrously multiplied that young bluebirds had such an opportunity in +life as their fellows had not had for many long years. Accordingly +they thrived as never before, and, of their progeny, a larger +proportion lived to the following year. It was only a few years before +the number of bluebirds had risen. Now we probably have as many as we +have had for a long time past. I cite this simply to show that a +region can support a certain number of animals of any one particular +kind, and that the animal is likely to multiply, if given a fair +chance, until it has reached such proportions. Now to my story of the +rapid development of a newcomer. + +In the year 1850 a resident of Brooklyn came home from a trip to +Europe. He was a lover of birds, and while in Europe had been +particularly attracted, no one now knows quite why, to the common +House Sparrow, as it should be called. It is no more abundant in +England than in many parts of the continent of Europe. A name that has +been used for a long time is very hard to cast aside, and we shall +probably continue to mistakenly call him the English Sparrow to the +end. Our Brooklyn traveler brought home with him from Europe eight of +these interesting little birds and succeeded in inducing his +colleagues in a scientific society to share his interest in them. Not +wishing to commit the newcomers suddenly to the rigors of the American +winter, these men built a large cage for the sparrows, meaning to set +them free in the spring. For some reason or other when the winter was +over the birds were all dead, and this first attempt to introduce the +sparrow into America failed entirely. The little bird had won so many +friends that his success was now sure. Finding a favorable +opportunity, these Brooklyn men dispatched an order to a man in +Europe, asking him to supply them with one hundred English sparrows. +The consignment came in good shape and the birds were liberated on the +edge of Brooklyn. This was the first of a number of introductions. A +little later New York City sent for two hundred and twenty of these +interesting creatures and turned them loose in her parks, while +Rochester, with what was then considered great public spirit, +purchased one hundred for herself. But the most progressive city in +this respect was Philadelphia. She had long been troubled with the +spanworm on her trees. This detestable larva had the unpleasant +fashion of lowering itself by a long silken thread from the shade +trees then so abundant in that beautiful city. The spanworms traveling +around over the clothing of the passersby were so objectionable to +everybody that it was with greatest delight that Philadelphia heard +of the new birds which ate the pest. One wonders why some +ornithologist did not look at the bird long enough to see that it had +the sort of a bill characteristic of birds that eat seeds. It is true +that most birds feed their young on insects, hence there is a time +when any bird is apt to be insectivorous. But the structure of the +sparrow's bill, like that of all finches, should have warned these +bird-lovers that the sparrow was not to be depended upon to earn his +living by catching worms. It is easy, however, to be wise after the +event. Philadelphia believed she was engaging in a particularly +advanced movement when she imported from England one thousand English +sparrows, nearly as many as were liberated by all other cities +together. These birds were turned loose among the shady streets and +wide spreading parks of the City of Brotherly Love. + +It is a serious matter lightly to disturb the balance of nature by the +introduction of a new species. It is true that the sparrow did eat +some spanworms and for a while enthusiastic bird-lovers hoped that +here was the solution of the difficulty. Philadelphians will also +remember that, with the spanworm removed from competition, the tussock +moth, whose caterpillar carries on his back a series of yellow, red, +and black paint brushes, at once become the permanent parasite of the +long-suffering shade trees. This caterpillar is covered with bristling +hairs, very closely set. Almost any bird objects to hair in his +victuals; and this particular larva has hair more than ordinarily +objectionable, for it irritates wherever it pricks the sensitive skin. +This coating seems to protect the caterpillar from the sparrow, with +the result that Philadelphia's trees were soon nearly defoliated by +this comparatively new pest, worse than the spanworm. With the paving +of the city's highways and the consequent shutting off of the air from +the roots, the trees have largely disappeared from the streets of +Philadelphia. With them have gone a fair portion of the tussock worms, +but the sparrow holds his own. Here is a new bird in the field, and +the struggle for existence on the part of every other kind of bird is +now more complicated and severe. The sparrow can live where the rest +of the birds have no possible chance. He throve so well in this +country that by 1875 he had spread over five hundred square miles in +the neighborhood of our larger Eastern cities. Thus far almost +everybody was pleased with the new introduction. Within the next five +years he had spread over more than fifteen thousand square miles, and +wise men were beginning to feel doubtful of the virtues of their +aforetime friend. When by 1885 more than five hundred thousand square +miles had been occupied by the enterprising little fellow, there +remained no longer a doubt in the minds of most people that the +sparrow was an unmitigated nuisance and great fears were entertained +that he had multiplied to such an extent as to be a serious menace. +Here, then, is a modern instance under our own eyes of a victory in +the struggle. If the sparrow has multiplied rapidly, while all the +other birds have either only held their own or even have diminished in +numbers, it is quite evident he must be better fitted to the +conditions than they are. What are his fit points? Why does he succeed +while others fail? The thoughtful bird-lover will have little trouble +in understanding at least some of his victory-winning characteristics. +How did he come to be almost the only bird who can live in large +numbers in our great cities, without losing his ability to get along +in less crowded situations? + +In the first place this interesting bird is a clannish fellow. He has +lost the ordinary sparrow habit and has come to like to live in +crowded groups. Seclusion is not at all to his taste, and if there are +only a few sparrows in the neighborhood those few will most certainly +be found living near each other. One of the early adaptations of the +sparrow to his city surroundings was the ability to find for himself a +considerable proportion of his food in the undigested seed that could +be picked up from the droppings of the horses. This naturally led the +surplus sparrows out through the many thoroughfares leading from any +large city. Where horses went sparrows could follow. Accordingly along +the great lines of travel this bird found the simple path by which he +could enter new territory. Meanwhile box-cars came into our large +cities with freight. Sometimes they had carried grain, sometimes +cattle. In either case it was not unlikely that a certain amount of +grain should be found scattered over the floor of such cars. The +sparrow visited these cars for the grain, and it must have been no +infrequent accident that a door should be shut upon a group of +sparrows, especially in inclement weather, when they were apt to be +huddled in a dark corner of the car. These prisoners would be carried +to the destination of the car and there liberated, thus producing a +new center of what we are now inclined to call infestation. By such +means the English sparrow has spread over much the larger portion of +the American continent. Few birds are bold enough to visit a railroad +car. Of the few who might be tempted, most are timid enough to fly on +the first approach of man. Hence they fail to gain this chance of +spreading. They must remain in the old crowded home. Meanwhile the +sparrow, thus transported, finds a new home with fewer or no sparrows. +The struggle is less keen. More of his kind can live. His boldness +has been here a fit quality and has helped him in the race. + +Man is only slowly coming to be a city-dwelling animal. Although it is +a voluntary process with him, he still usually visits the country with +much enjoyment. He has not as yet learned to adapt himself thoroughly +to the city, for somehow city life kills him. Families that move into +the city gradually have a smaller number of children in each +generation until shortly the family is wiped out. The population of +the city must constantly be replenished from the country. But the +English sparrow is more adaptable than are the people. He has made +himself at home in the heart of the biggest city. The Wall Street +canyon is not deep enough, nor contracted enough, nor free enough of +food to blot out the life of the English sparrow. At the heart of the +deepest gully among the skyscrapers of our biggest cities we find this +little bird hopping between the horses' feet, darting out from under +the wheel of the push-cart, fluttering only a few yards to a place of +safety, to return at once to his scanty meal upon the pavement as soon +as opportunity offers. He is a typical city dweller and has learned to +thrive there. Again in this matter he has distanced other birds to +whom the city is more deadly than it is to people. + +Another very important element in his fitness for the struggle of +life lies in the fact that he is unafraid of man. He is wary of man; +by which I mean he will quickly fly up from in front of man's feet. It +is exceedingly difficult to catch a sparrow in one's hand. It is far +easier to lure a pigeon within reach. But the sparrow, when escaping +your hands, comes to rest but a slight distance away, only to elude +you quite as successfully if you try again. If the sparrow is let +severely alone he becomes more and more familiar with men, flies less +promptly, and goes a shorter distance, but any attempt to trap him +renders him shy more quickly than almost any other bird we have. He +soon learns to avoid a trap in which his companions have come to +grief. Those who would poison or trap sparrows must change constantly +the base of their operations. This fearlessness of man is a valuable +asset to the bird, for it is an important defense against other foes. + +The most serious enemy the birds at large have, after man himself, is +the bird of prey. Hawks and owls capture a large quantity of our +smaller birds. Now the hawks and owls are for the most part shy of +man. They have gotten a bad reputation, especially if they are of any +size, because of their more or less pronounced proclivities for +seizing our domestic poultry, and consequently many people will fire +upon a hawk or an owl who would probably fire upon no other bird. By +living close to man the sparrow is largely saved from the danger of +capture by these carnivorous creatures, and this is the first and a +very important element of the advantage to the sparrow of living near +man. But there is the additional advantage that man scatters about +him, in one way or another, a very considerable amount of waste food. +I have suggested that the seeds in the droppings of the horse form a +large proportion of the sparrow's food, and horses are to be found +only with men. In the neighborhood of man's home, unless he has become +sanitary to a degree which has only been attained in recent years, +there is usually more or less garbage, kitchen offal of one sort or +another. To this the sparrow has easy access and from it he makes many +a meal. But this fearlessness of man gives him still another advantage +which his competitors fear to use, it provides him with nesting sites. + +Man has the faculty of putting up ornamental trimmings on his house, +and there is no spot the sparrow chooses more willingly in which to +build his nest than the ornamental quirks and cornices of man's +architecture. A Corinthian column with comely leaves in its capital +seems especially designed for the comfort of the sparrow, and his +distinctly untidy nest is the familiar disfigurement of almost every +ornate public building. These are the advantages which come to the +sparrow from his willingness to associate with man, and there are +comparatively few birds with whom he must share them. Few birds select +the immediate neighborhood of man's home for their nests. They may +live in the neighboring trees, they may haunt his orchard, but his +house, for the most part, they decline to frequent. + +Still another quality which makes for success in this buccaneer is the +willingness with which he will vary his food as occasion requires. It +is a not infrequent characteristic of the bird family that each +species should have its own rather restricted diet. Birds are quite +particular eaters, and many of them will come well nigh to starvation +before they will use unaccustomed food. The sparrow, on the contrary, +like man, eats almost anything he comes across that could reasonably +be considered edible. He belongs to a group of birds which are +structurally adapted to cracking the hard coats of seeds. This group +of birds known as the finches is provided with the sort of bill +familiar in the ordinary canary bird. It is short, heavy at the base, +comes quickly to a point, and is firm and strong. With it the bird +readily breaks through the hard outer coat of most seeds and feeds +upon the rich cotyledons that are enclosed within. Nowhere in its +entire structure does the plant crowd so much nourishment in so little +space as it does in the seeds. It is not by chance that the great +human food is grain. The sparrow belongs to the one bird group that +makes a specialty of such seeds. + +Most of the English sparrow's cousins in this finch group confine +themselves rather rigidly to this diet. Here the variability of the +sparrow again gives him the advantage. He may have the family fondness +for seeds, but in their absence he can be content with almost anything +edible. In the early springtime, when the seeds of last year are gone +and those of the new year have not yet been produced, the sparrow is +not averse to eating young buds from the trees. At this time he is not +unlikely to eat our sprouting lettuce and peas. It is easy to be +severe on him in this matter; but for a creature like man, who has the +same tastes, who eats the enormous buds of the cabbage, the +cauliflower, and the brussels sprouts, or the more tender buds which +he calls heads of lettuce, it seems particularly inappropriate that he +should throw stones at this little creature whose tastes are so +similar to his own. + +While seeds are more suitable for an elder bird they are altogether +too indigestible to be the food of nestlings. So when the sparrow +finds its nest full we know he must sally forth in search of +nourishment more simple of digestion. Now for a few weeks he searches +assiduously, catching insects and caterpillars of various kinds, and +feeds them to his young. This taste passes as his children grow older, +especially as shortly the seeds begin to ripen. Now is the time for +the sparrow to fatten. Now he is eating the food for which he was +really built. By the time the wheat is ripe there are sparrows enough +about to form quite a flock, and when these settle down in a wheat, +rye, or oats field and feed upon the grain, meanwhile shaking out upon +the ground perhaps as much as they eat, the farmer begins to realize +that the sparrow is not his friend. + +When winter comes the struggle for existence among the birds is +intensified, and comparatively few of them dare face it. Most of our +birds betake themselves to less rigorous quarters, leaving to the +sparrow a comparatively small number of competitors for the diminished +supply of food. As long as the snow is off the ground the sparrows can +find sufficient sustenance. They gather themselves into groups and +sally out from the city into the open country. The immediate result is +that great quantities of weed seeds are seized upon by the English +sparrow, as, indeed, by every other finch which is with us in winter. +Perhaps we have not given the little fellow credit for the good he +does at this particular time, for the rest of the account truly does +not help him in our esteem. + +There is a further direct advantage in the sparrow's sociability. One +robin may nest in the vines about your porch. If there were room for a +dozen, scarcely more than one would be likely to use it, because he +would drive away any other robin who attempted to share the +neighborhood with him. To the sparrow company is always in order. +While he may quarrel from morning until night with his fellow, it is a +sociable quarrel and neither would willingly forgo it. This union is +strength among birds, as with man. Every animal is safer from his +enemies when he can have the constant presence of others of his own +kind. The deer that stays in the herd is safer from the wolves. It is +only when the latter succeed in cutting out some weaker or less +sagacious animal that these carnivorous creatures succeed in tearing +down their prey. I think the superiority of the sparrow over most of +our common birds, when considered as a city dweller, is scarcely +understood. Because he had won in the race with other birds is no +necessary indication that he warred directly against them. Bird-men +often attribute to him a quarrelsome disposition, as if he actually +drove other birds away. It almost seems like animosity against the +sparrow to speak of him as attacking blackbirds and crows. It is a +cowardly crow who can be driven away by a sparrow, and if the two +cannot live together it seems to me certainly to the discredit of the +crow and not of the sparrow. I believe the truth to be that, while +the sparrow is undoubtedly a quarrelsome fellow, his bickerings are +his form of social converse with those of his own kind. A quarrel +among themselves seems not to indicate animosity, but would appear to +be the sparrow's idea of conviviality. It rarely leads to serious +results. I have never seen a male sparrow trounce any other bird with +half the vigor that I have occasionally seen the mother sparrow evince +when she caught her male companion by the feathers of his head, hung +him over the side of the limb, and vigorously and thoroughly shook him +until he desisted from his annoying and possibly insulting attentions. +The truth of the matter is that a colony of these little birds, with +their continual social chatter, including their quarrels, makes such a +continuous noise that the ordinary bird, which is generally of rather +quiet disposition, is too much annoyed by the unending nuisance to +find the neighborhood at all to his taste. Where a large number of +sparrows have gathered together the conditions are such as would give +a robin or a bluebird nervous prostration, and his only recourse is to +depart to a neighborhood where there is more peace and quiet. But our +English sparrow is not only better fitted for the struggle than the +robins and bluebirds, the orioles and the wrens. He has one important +advantage over even his own sparrow cousins. The males are +handsome--much more so than the females or than their sparrow cousins +in general. + +In the song sparrow, field sparrow, chipping sparrow, and the fox +sparrow the male and female are very nearly alike in color. It often +becomes necessary for the bird-man to examine the internal organs of +the bird he is stuffing before he can certainly decide its sex. But +there is no difficulty whatever in telling the male from the female of +the English sparrow. The male is far the more ornate bird. His back is +striped with a richer brown; his head has two splendid dashes of +chestnut over the eyes; his throat and breast are splashed with red +and lustrous black; his bill is a clear fine black. Altogether the +bird is strikingly colored for a sparrow, and this characteristic is +the more remarkable when we see how quiet and somber is his more +modest mate. This brilliancy of male plumage in the presence of the +somber color of his mate would seem to indicate that the English +sparrow is eye-minded rather than ear-minded. It is true among human +beings that most of them are eye-minded. That is to say, they notice +things with their eyes chiefly. Memories they have are memories of +things seen; recollections of their friends bring up the appearance of +their friends. Their language is full of metaphors which imply form +and shape. But occasionally we come across an ear-minded person. He +remembers voices quite as well as he remembers faces. To him music is +an unending delight, and painting and sculpture fall into a distinctly +secondary place. This is ear-mindedness. Now, most of the sparrows +seem to be ear-minded, at least as far as their recognition of their +mates are concerned. In this group beauty of song is developed many +times oftener than is especial ornateness of plumage. The bird-lover +who is himself keen of ear is never tired of listening, when in the +field, for the two low notes with which the vesper sparrow introduces +a song, the rest of which is not at all unlike the one of his +song-sparrow cousin. The field sparrow begins more like the song +sparrow, but ends with an often repeated note, which not a little +resembles in general character the somewhat more monotonous song of +the grasshopper sparrow or of the chippy. In comparison with these +melodious birds the English sparrow makes no showing whatever. His +voice is harsh and querulous, although very occasionally it is +possible for the bird-lover to detect a note or two which would +indicate that, if he were properly educated, his voice might amount to +something. He wins his wife not by his pleasant voice, but by his +attractive appearance and his winning ways. We have every right to +infer from the character of its fellow birds of the sparrow family +that once the female and male sparrow were colored about alike. But +Madam English Sparrow was apparently eye-minded rather than +ear-minded. Whatever pleasant voice a suitor might have seems to have +been to her without attraction, and there was nothing to encourage him +in developing it, nor was she likely to mate with him for it and +transmit it to her male children. On the other hand, let a suitor +appear in whom a more brilliant coloring proclaimed his superior +vigor, and this seems to catch her eye at once. The less accomplished +rival in the tournament of love seems to have been already forgotten. +To their children these successful characteristics were naturally +handed on and led to equal success on their part. If any of these +children possessed this badge of honor in a more than ordinary degree, +he was the more likely to win a mate and thus again the opportunity of +passing on to his offspring his own distinct advantage. Generation by +generation the males have become more beautiful and the females more +discriminating. That the bird is either instinctively or actually +conscious of this advantage would appear from the constant fluffing of +his feathers and spreading of his highly colored wings with which he +evinces his admiration for his ladylove. Even the most hardened +dweller in the city can scarcely have failed to see the sparrow spread +his wings, fluff his feathers, and sink close to the ground, twirling +and gyrating about the object of his affection. It must give him a +shock to see how often she proves temporarily or hypocritically +indifferent to the demonstrative proceedings. Indeed they may +terminate in a thorough trouncing of the male on the part of the lady +of his affections. Now this preference for color over song must have +evidently evolved in connection with the development of social habits +in the English sparrows. His cousins of the fields, our native +sparrows, are much less social, much less likely to be met with in +flocks. To birds who scatter more, beautiful song is a great +advantage. It can be heard at a long distance. But when birds flock +together a much better advantage is that of beautiful clothing, added +to alluring ways. + +But we have not nearly exhausted the catalogue of the traits belonging +to our little friend which give him the advantage over other birds in +the struggle for life. His ability to remain with us in winter when +most birds are gone stands him in good stead. + +It is readily observed by one who pays the least attention to outdoor +life that winter finds us with comparatively few birds. North of +Maryland and the Ohio River the robin is practically absent in the +winter, except in much diminished numbers close to the border. The +bluebird is similarly absent; the great flocks of blackbirds are gone; +the bobolink is missing entirely; the thrush and the catbird have all +left; the flicker and red-headed woodpecker are also spending their +winter in the South. The great mass of our bird population has left us +until warmer weather shall bring back to us once more our feathered +friends. It is true that we are south to the snowbirds or juncos, and +their little slate-colored bodies, with their light breasts and their +white on each side of the tail, make our bare hedge rows brighter by +their presence. A few of our birds like the song sparrow and the +cardinal are hidden away in the thicket, and have not all joined their +comrades in the south. + +The English sparrow was once probably quite as migratory as any of the +rest of these, but a great change has come over his habits. With his +newly acquired fondness for the haunts of men he has suffered a change +in this respect also. Whatever may have been his reason for migrating, +it no longer holds. He now finds himself quite able to stand the cold +of winter. Accordingly he never leaves us, except very temporarily. +When the migrating season comes the sparrows of the neighborhood are +very likely to gather themselves together in a single group and take +to the neighboring country. I believe this flocking on their part at +this time of the year is a remnant of the old migratory habit. Until +snow covers the ground the sparrow is not likely to be seen again in +such numbers in the city. The advantage the sparrow gains over his +competitors by not going south does not appear during winter. When +spring comes, however, his gain is evident. He has his choice of all +the nesting sites in the region. When the migratory birds return every +first-class place is filled by a sparrow's nest. Nothing but second +choice situations remain, and with these the late comers must be +content. When we consider how much the safety of the next generation +depends upon the security of the young while helpless in the nest, we +appreciate what the English sparrow has gained by staying throughout +the year. Often while the season is so inclement that it would seem +there is still danger of frost, the sparrow builds her nest. All sorts +of places are open to her choice. She will find a protected corner +under a roof, above a spout, in the corner of the porch, behind an +open shutter, in the vines against the side of the house, on top of an +old robin's nest in the tree, in the bird boxes which have been put up +for more desirable creatures; anywhere and everywhere this industrious +little mother is liable to build her nest. Her husband will help her +more or less in the task, often bringing material and helping to place +it in the negligent pile of which their nest is composed. But he does +a good deal more fussing and cheering up than he does actual work, and +she seems to depend much upon his cheerful presence for her happiness. +It is hard to discourage Madam Sparrow when once she has set her mind +on home-making. A bird-lover, some time since, reported how a pair of +sparrows had started to build a nest upon his lawn. He, wishing to +interfere with the process, took a small rifle and shot the male bird. +Within twenty minutes the female, who had scouted round the +neighborhood, returned with another mate and resumed her nest-building +process. Again he interjected the tragic note into her life by +shooting her second husband, only to find her start out in pursuit of +a third, with whom she returned in the course of an hour. He felt that +by this time he had interfered with her domestic happiness as much as +he had any right to do, and suffered her to continue her housekeeping +with her third husband without further molestation. I imagine it would +have puzzled both birds to tell who was the father of the nestlings +who appeared two weeks later. + +Not only do sparrows nest early, they nest often. I suggested to one +of my students that she locate as early in the season as she could the +nest of a pair of English sparrows, which was sufficiently accessible, +and that she keep it under observation at intervals of a few days +throughout the summer. In the fall she came to me with glowing eyes +and gave me her report. "It is simply great," she said. "I never went +to that nest a single time this summer to find it empty. When I first +got there I found four eggs; after a while these hatched out, and the +young were on the nest until they were old enough to fly; but before +they had left she had slipped a fresh egg among them, ready to start a +new batch. Whenever I saw the nest throughout the entire summer, I +found in it either eggs, or young, or both." Such reproductive energy +as this is hard to beat; compared with this rate of increase, the +ordinary bird is the exponent of race suicide. How can a robin hope to +compete with this family industry? What can a bluebird offer that will +approach such chances of a worthy successor when his work shall be +finished? + +These, then, are the most important points in which the English +sparrow has varied from his sparrow cousins and made of himself the +most successful town dweller in the bird world. He has become clannish +and gained the advantages of coöperation. He has used man's highways +and cars by means of which to expand his area. He has cultivated the +presence of man and thus gained protection from his enemies, food from +man's waste, and nesting sites on man's house. He has assumed a varied +diet. The male has become handsome. He has given up migrating, and +thus secured the best nesting sites. He has learned to produce many +offspring. With all his versatility, why should he not succeed? + +Thrown into competition with our native birds, he easily beats them +on their own ground. He survives against the competition of birds +which seem to us more estimable in every way. The very fact that he +survives proclaims his superiority over them, and shows that our +criterion is not the one by which nature judges. We like the birds +which serve our purpose. We admire the brilliant plumage of the jay, +cardinal and goldfinch. We love the mellow notes of the woodthrush, +and of the veery, the clear, rollicking outpourings of the bobolink, +the musical love song of the brown thrasher, the cheerful scolding of +the wren. We are fond of the birds who busy themselves taking the +insects out from among our grain and from off our fruit trees. We can +only understand the value of the bird to nature when he is valuable to +us. So, because the English sparrow does little that is to our +advantage and much that is to our annoyance, he is in our estimation a +reprobate and an unending nuisance. + +All sensible bird-men must clearly acknowledge that he is a very +undesirable citizen. I write the above sentence to show that I realize +the whole duty of the bird-lover in the matter of the sparrow. This +pestiferous creature should be exterminated by traps, by grain soaked +in alcohol, or strychnia, by fair means or foul. But personally, I am +taking no share in his destruction. Any bird-lover, after reading the +foregoing account, can scarcely have missed the undercurrent of my +affection for the little rascal. He is a thorough optimist; he is +absolutely persistent; no hardship seems to dampen his ardor. His +heart is valiant above that of most birds so that he has dared to make +of man his near neighbor when other birds consider him their worst +enemy. I love him for it. When I am in the midst of a big city with +its cliffs of offices and its gorges of paved streets, it is to me a +cheer and a delight to see this happy little fellow who has adapted +himself to circumstances against which no other bird, excepting the +pigeon, can cope. I confess that it would be with regret that I should +see him disappear from the landscape. I have missed a long line of +spring peas through his ravages, and he has objectionably decorated +many places about my own home. But I have yet the first violent hand +to lay upon the sparrow, and I doubt whether my hand is ever to be +reddened with his blood. + +I am going to ask bird-men to forgive me if I say that I believe, +although I speak only from general impression, and not from careful +research, that the sparrow within the past eight years has reached his +equilibrium in the neighborhood of Philadelphia and is growing no more +abundant. Meanwhile another and very desirable state of affairs is +arising. Bird love and bird protection are so active in this +neighborhood that there is growing to be a new race of birds who lack +the fear of man their ancestors justly had. Under these conditions the +wild birds, which for a while we believed to have been completely +driven out by the sparrow, are rapidly returning to our villages and +towns, and we have many more robins and catbirds, wrens and flickers +than we had ten years ago. We have seen the worst of the English +sparrow; he has now found his equilibrium. + + + + +CHAPTER IV + +ADAPTATION FOR THE INDIVIDUAL + + +Among the standard books of the classical curriculum in the +denominational college of thirty years ago was a volume which I +suppose has practically disappeared from such courses. It delighted +many of its students for a reason entirely different from that which +the author meant should be its taking feature. It was Paley's "Natural +Theology." The author started with a story of a watch found by a +savage. This child of nature was supposed to examine its mechanism and +to infer that the watch was made for a definite purpose. As I +remember, he was even supposed to discover that its purpose was to +mark time. It was at least to become clear to his savage mind that +this was no chance object, but was the definite product of a designing +mind. Having brought this hypothetical savage to these conclusions, +the author turned himself to savages nearer home who fail to see +design in nature. The book takes up a great many cases of interesting +facts in animals and plants as clearly showing evidences of design as +did the watch our savage picked up. But the inference we were expected +to draw was that the design shown in nature argued clearly for a +Designer above nature; in other words, that nature was unintelligible +without God. Everyone in the class believed in God without this +preliminary, and consequently the book was unnecessary, so far as we +were concerned. We started with the condition of mind which the author +hoped to produce. One effect the book did have; in the absence of any +other reputable course in zoölogy, it gave us an astonishing +collection of interesting facts about animals. + +Some of Paley's statements were certainly peculiar. His Malay pig with +its upper teeth wonderfully curved was said to be in the habit of +hanging its head upon a bush while it slept, in order to save the +strain upon its porcine neck. This was too much even for our +credulity. None the less the impression made upon some of us by the +evidence for design in nature has never left us. + +Among many scientists to-day it is supposed to be crude to speak of +purpose in nature, and there is reason for their attitude. But the +statement that there is no such plan conveys to the ordinary thinker a +meaning that is far more erroneous than could possibly exist in his +mind should he believe implicitly in design and purpose. As between +design in the universe in the usual sense of the word, and a purely +accidental connection of events in the universe, there can be no +doubt as to the choice. The truth is far better expressed by the word +design than by the chaos which is the alternative idea in the average +mind. In these later years we have come to use a different word. We +now conjure in such connection with the word adaptation. In every +animal and every plant the trained eye sees unending examples of +adaptation; that is, of a fittedness to the work it has to do. The +modern scientist feels sure not only that the animal is fitted to his +work, but that he has been so fitted by the work; that the very use he +makes of his organs has determined their structure. This work has +decided that the structure which he has is the structure that shall +survive and shall produce other structures like itself. Adaptation +therefore does not simply express the idea that the animal is adjusted +to its surroundings, but it further suggests that the animal by +gradual process has become thus adjusted. The word adaptation applies +not simply to the result, but also to the process. The scientist does +not consider the animal a final and complete result. He thinks it +still in a state of flux, and so long as its line lasts it will be in +a state of flux. Change is about it on every side, and it must adapt +itself to this change or it will pass away. It may adjust itself, as +has been previously stated, by moving to another environment in which +it feels more at home, but unless it does this, if there come much +change in its present surroundings, it must either meet the +difficulty by altering itself, or it must give up the struggle. The +alteration is unconscious so far as the animal is concerned. It is +seriously to be doubted whether there is any recognition of the +process on the part of any animal excepting man. But though the +process be unconscious, it is none the less there. Slowly and +gradually the animal and the environment are becoming adjusted to each +other. + +While it is exceedingly difficult to lay our hands on any animal which +is at present visibly changing its structure, it is not hard to find +closely related animals. These are nearly alike in structure in most +respects. In a few points, however, they may differ materially, and +these points are often directly concerned with different habits of +life. Considered in this aspect, these adaptations of a single organ +separately examined form an excellent argument in favor of that +gradual alteration of the entire organism which evolution suggests. + +The most primitive struggle in which an animal can possibly engage is +the effort to maintain its own life and vigor. This struggle will +result in certain adaptations for the individual, adjustments which +make for the safety of the animal himself. These form the subject +matter of the present chapter. + +The farther up the animal kingdom we pass in the study of adaptation, +the more likely we are to find changes which have but little bearing +on the safety of the individual. They work for the good of the entire +species, sometimes to the distinct disadvantage of the individual. The +King Salmon may make its long run to the headwaters of our western +rivers, deposit its eggs, have them fertilized, and then float down to +death. But it does not die before abundant preparation has been made +for the continuance of the race. Such adaptation for the good of the +species will be considered in the next chapter. + +The first and most important struggle any animal has to enter is the +never-ending battle for its food. Occasionally there is a similar +straining after the air it breathes. But ordinarily air is +sufficiently abundant, except to animals living in the water, where +the supply is always more or less restricted and easily becomes +exhausted. But food is the constant need of every organism, and most +creatures die for lack of it. In this struggle the animal is pitted +against those of his own kind, rather than against those of other +species. Even his brother is his enemy, for he desires the same food. +In many a nest of birdlings one of them fails to reach its development +simply because the parent either is unable to find or it cannot carry +enough food to satisfy all the hungry mouths in the same nest. Before +the nestlings are ready to take their place in the struggle for life +outside and hunt their own living, one or more of them has succumbed. + +After the battle for food comes the struggle for shelter. For most +animals there is no such thing as shelter. They are exposed to the +inclemencies of the weather and to the depredations of their enemies +without the means of retiring into any situation which might protect +them. In the higher animals, especially when they are warmer blooded +and their bodies must be kept at a higher temperature, some form of +covering has come to be almost universal. + +Though comparatively few animals are prepared to seek shelter from the +cold, all of them have enemies against whom they must battle. These +foes may wish to eat them or may simply wish to get them out of the +way. In either event this struggle is so persistent and so keen that +after starvation it is probably the source of the largest loss to the +animal kingdom. + +Considering first the feeding habits of animals, we find they are +exceedingly varied. Some creatures simply engulf other and more minute +animals, often only microscopic in size, in such quantities as to +satisfy their hunger. Others, feeding upon larger plants or animals, +must have some means of breaking off particles of this food; still +others confine themselves entirely to nutritious fluids, and must have +organs adapted to this particular type of food. + +Insects are so common that anyone, who cares to, may easily verify +what is here described. It will take nothing but a clear observant eye +and a little patience to make out what is suggested. Each of our +common insects has one of two clearly defined habits in the matter of +food. Either it eats solid food, which must be made fine before it can +be taken into the mouth, or it feeds upon liquids. These liquids may +be easily accessible like the nectar of flowers, in which case one +sort of mouth will serve; or they may be the juices inside the tissues +of animals and plants, when an entirely different type of mouth must +be employed in their acquisition. Perhaps the most easily found +representative of the biting type of mouth, which breaks up solid +food, will be seen in the common grasshopper. Doubtless each one of my +readers has at some time taken a grasshopper into his hand, and, +holding the tip of his finger against the insect's mouth, has promised +the creature its freedom on condition that it disclosed its +reprehensible habit of chewing tobacco. The grasshopper surely +complied, and I trust the promiser was as good as his word. The +grasshopper's head is so placed that, while it is at the front of its +body, the mouth is directly on the under side of its head, while the +eyes are at the top of the front of its face. Under these +circumstances it cannot see what is going into its mouth, and this +makes an interesting variation of conditions to which it must adapt +itself. The means by which it accomplishes this will be clearer if the +mouth of the grasshopper be compared with our own. Our lips are upper +and lower, but the grasshopper has a front lip and a hind one. The +broad front lip is easily seen at the forward side of the mouth. Just +behind it, serving the purpose of our teeth, is a pair of hard jaws +with horny tips upon them, which serve to break small pieces from its +food. While our jaws and those of all other backboned animals work up +and down, so that we may be said to have an upper and lower jaw, the +grasshopper and all of his insect, crab, or spider relations, which +have jaws at all, have them right and left, and they work from side to +side. Behind these harder mouth parts is found a pair of softer jaws, +each of which has on it a little finger-like feeler. With this pair +the insect holds its food while the hard jaws break it to pieces. The +hind lip follows, and is also provided with short finger-like feelers. +The feelers on the hind lip and on the soft jaw are necessary because +the eyes are so placed as not to be able to see what goes into the +mouth, hence the insect must make up for the loss of sight by the +addition of touch. The same type of mouth as the grasshopper has will +be found among the beetles. Here the males sometimes have the hard +jaws so enormously enlarged that they are known as pinchers and have +given to their owners the name of pinching bugs. All insects with such +jaws as these use them for breaking up solid food. + +A glimpse at the mouth of the butterfly captured on an adjoining +flower will show a most remarkable variation from that seen in the +grasshopper. Practically all of the mouth parts mentioned are present +in this insect, and its early ancestors had their organs practically +like those of the grasshopper. Now they are so modified and united +with each other as to be almost unrecognizable. The pair of soft jaws +has become very much elongated, and they lock together in such a way +as to enclose a hollow space between them through which the creature +can suck its fluid food. Not only have these soft jaws joined +together, but, because they have become so much elongated when not in +use, they must be coiled up like a watch spring and laid between two +hairy lip-like processes which correspond in reality to the two +finger-like feelers of the grasshopper's hind lips. + +The butterfly, lighting upon the corolla of the flower, uncurls this +long "tongue," and through its hollow center pumps up into its crop +the nectar which the flower has stored in its base. When the butterfly +comes to get the nectar from the flower, it rubs upon its own hairy +body pollen from the stamens of the flower and carries it to the +pistil of the next flower of the same kind which it visits. Most of +us have at some time sucked the nectar from the back of a torn +honeysuckle blossom and approved the taste of the butterfly in this +matter. If the airy creature be watched as it lights upon a flower, it +will not be difficult to see it uncurl this long tongue and probe the +depths of the flower. If the butterfly be taken in the hand and the +tip of a pin inserted in the center of the coiled tongue, it can be +uncoiled without the slightest harm to the butterfly. + +Insects which wish to use for their food the juices of other animals +or of plants do not find them so easy to gather. In the mosquito most +of the mouth parts are developed into slender pointed bristles wrapped +in a hind lip. These bristles serve to puncture the skin of the +creature attacked, while the curled lip serves as a tube through which +the blood may be extracted. + +If, while sitting on the porch on a warm summer evening, mosquitoes +begin to annoy, let one of them at least serve to show his method of +procedure before he is destroyed. Allow the creature to alight upon +the back of your hand and slowly raise the arm until the eye looking +at near range can see the head of the mosquito, which, by the way, is +sure to be a female. Males in this species are entirely harmless. They +never eat after they have grown up; that is, after they are truly +mosquitoes. But the female is very assiduous. Alternately raising and +lowering her lancets from either side, she pierces, then saws, her way +down through the flesh until she has buried her instruments in her +victim and her head rests against her prey. Now a pumping motion of +the abdomen will be apparent, and this continues its accordion-like +action until it becomes more and more distended. The insect only gives +up its task when the entire abdomen is swollen into a great red ball +of blood. The mosquito will now slowly withdraw its instruments and +retire from the scene, if permitted to do so. If there is any fear of +annoyance from the bite, a drop of ammonia immediately applied will +counteract any irritation which would have been produced by the saliva +of the mosquito. The insect is not intentionally vicious in this +procedure. It is simply gathering its own natural food, though this +does not make it less annoying to us since we are its victims. The +swelling produced after the bite is the result of the action of the +saliva the mosquito injected into the wound. The opening through the +tongue is so small that blood would readily clot inside the tube and +prevent its further usefulness, did not the mosquito inject the +secretion of its salivary glands into the wound. This acts upon the +blood in such a way as to prevent its coagulation. + +Anyone who thinks carefully can add numberless specializations for +food getting. For instance, primitive mammals have little pointed +teeth which fit them for feeding on insects. In each of the great +order of mammals a special development of these teeth has occurred. +Among the rodents or gnawing animals the front teeth have become long +and chisel-shaped for nibbling. The horse has formed them for nipping, +and his hind teeth for grinding. In the dog the teeth near the front +have become long for tearing his flesh food, while his hind teeth, +working with the motion of scissors, cut it into pieces. + +A second great class of specialization is seen in the changes of habit +that provide the animal with shelter. The home seems so necessary a +part of human life that it is almost impossible to think of an animal +having nothing that in the faintest degree could be called a home. We +at least expect it to have some sheltered place in which it passes +most of its time and to which it returns after its wanderings. The +great majority of all animals have no such home. The place in which we +find them to-day may not be the place in which they will be to-morrow. +All places are alike to them. The ordinary conduct of their daily life +drives them about in the search for food. Their attempt to escape from +their enemies leads them each day into new situations, and they may, +and probably do, have no power to recognize the old location if they +return to it. When we come to the backboned animals there is a little +more tendency to a stationary location. The sun fish may frequent the +same reach of the stream, the trout may haunt the same pool, year +after year, but a great majority of fishes doubtless move +indiscriminately up and down the stream or about the lake or ocean and +are not found two successive days in the same place. The same may be +said of frogs. For a time a particular frog may have a fondness for a +special bend in the stream, but it is only a temporary fondness, I +believe. + +Our own need for shelter is the prime motive in leading us to build a +home, and this necessity arises first of all because of our warm +blood. What we are accustomed to call cold-blooded animals are not +truly so. Their blood holds practically the temperature of their +surroundings. As the air or the water in which they live grows warmer +or colder the bodies of these creatures alter with it. Consequently +they are active when the temperature is high and grow more sluggish as +the thermometer falls. When the day grows distinctly cold the animals +may go practically dormant. + +Only the birds and mammals have warm blood, and of these the birds are +distinctly the warmer. Whereas the temperature of the mammals runs +from about ninety-eight to a hundred degrees Fahrenheit, that of +birds lies somewhere between one hundred and five degrees and a +hundred and ten. Creatures which are warmer than their surroundings +must have some protection against chilling. Accordingly both mammals +and birds have clothing. In the case of mammals the covering is fur, +in the case of birds feathers. In some of the tropical animals like +the elephant and rhinoceros, or in man, who has learned to protect +himself in cold regions by making clothing for himself, this hair is +very short, and except where serving for ornament is quite scanty, no +longer being of use as a protection. But the great majority of all +mammals are well covered with a dense coat of hair. In many of those +living in the colder regions there is in reality a double coat. The +fur seal of the Alaskan Islands is so provided. A set of long hairs +deeply fastened in the skin forms a covering, which shows on looking +at the seal. Underneath this layer, and set but lightly into the skin, +is a short coat of very much finer hair known as the underpelt. When +the skin is taken from the seal it is split by machinery into a lower +and an upper layer. When so split the deep-seated pits of the long +hairs are cut, and these hairs come out. The fine underpelt thus laid +bare is what is commonly known as sealskin. Fashion has decreed that +this must be dyed a rich brown, although when taken from the animal it +is nearly mouse gray. + +The birds have need for better clothing. To begin with, their blood is +much warmer, and hence needs better protection from outside cold. In +addition such of them as fly high must be prepared to stand great +variations in temperature. For these purposes birds need a covering of +the finest type. This clothing, in addition, must be extremely light +because the creature must carry it into the air in flight. All of the +requisite conditions are thoroughly met by the feather, which is the +lightest and warmest clothing known to man. If at night we wish, +regardless of expense, to keep ourselves warm with the lightest and +warmest of covering, we send to the Arctic Sea, and from the breast of +the eider duck we pluck the down which lies between the warm blood of +the duck with its temperature of one hundred and seven degrees and the +water in which the iceberg floats. + +Young mammals and birds, before their clothing has well formed, are +naturally susceptible to cold; this leads to the first genuine +approach to a home among animals lower than man. Birds lay their eggs +long before the creatures inside of them are ready to emerge. +Accordingly they have learned to build nests in which to place these +eggs, and to protect them from the outside air; meanwhile the bird +keeps the eggs warm by close contact with its own body. The lowest of +the birds may lay their eggs simply on the ground without any special +protection. As we rise in the scale of the bird world we find nests +provided for the eggs. These nests become increasingly complex and +specialized, until we reach the oriole's home with its wonderfully +woven mass of fiber, which, in spite of its apparent looseness, +supports well the weight of the mother bird and of her eggs. The +robin, not content with making a woven basket, plasters it with clay, +and makes an absolutely impervious nest. + +When we remember that both mammals and birds are the modern +descendants of cold and scaly reptiles of an earlier geological time, +it becomes interesting to compare their clothing. Evidently in the +mammals hairs began to come out between the scales. Gradually the +scales became fewer and the hairs more abundant until finally the +scales have all disappeared, except those that remain as the claws on +the toes. The ancestors of the birds, on the other hand, boldly +transformed their scales into feathers. + +Another need for shelter arises in connection with the approach of +winter. This problem of withstanding the cold season is complicated by +the presence of two new factors. First and most directly, the cold +itself is a distinct obstacle to the comfort of many of these +creatures; as a secondary result of this cold, the food of many +animals disappears entirely in winter. Most of our birds meet this +difficulty by changing their base of operations. When the north grows +cold these creatures fly to the south. Some of their migrations cover +enormous stretches of country. Our bobolink, so well known and loved +by all watchers of spring migrations, passes twice a year between the +latitude of New York and Rio Janeiro. One of our most careful students +of bird migration says that the Golden Plover makes, twice each year, +the long journey from the Arctic shores of North America to the plains +of La Plata. + +Different fur-covered animals have specialized to meet the winter by +any one of three different methods. They may brave it out, hunting for +their food as best they can all winter long. Such a course is pursued +by the rabbit. Again like the squirrel, they may store large +quantities of food during the summer, and on this provender they may +subsist during winter, remaining for most of the time near their +hiding-places, which, however, they may frequently leave upon warm +days. A third method is less common, but very interesting. The +groundhog or woodchuck is the best-known example of the group. It +remains asleep, or, as it is technically known, dormant, during the +winter. This stupor is more profound than ordinary sleep, and from it +these animals awaken with difficulty. It is needless to remark that +the groundhog's behavior on the second of February has no relation +whatever to the weather we are to have later in the season. This is +coming to be pretty generally understood. While the newspapers each +year comment upon the groundhog and his shadow upon that day, year by +year the notice has more of humor in it, and fewer people pay any +attention to it. + +As for the backboned animals which are cold-blooded, these must, +unless they are fish, give up the struggle completely, bury themselves +in out-of-the-way places, and go worse than dormant. They often become +absolutely cold and stiff. In the case at least of fish, it is quite +possible for them to be frozen stiff, even to be enclosed in cakes of +ice, and still to recover if the encasement is not too long continued. +But the snakes, the turtles, the toads, the lizards, all are hidden +beneath the ground waiting in absolutely unconscious rest the return +of warmer weather. + +After the need for food and shelter comes the continually recurring +necessity on the part of almost every type of animal to escape from +the unwearying persecution of higher creatures which would feed upon +it. The whole creation is a constant network of animals which prey +upon each other. It is the fate of a great majority of all creatures +to fall victim to other animals to whom they serve as food. +Accordingly nature has concocted many devices by which she assists +her favored children in escaping this relentless persecution. Perhaps +the most widespread means which animals have developed in order to +elude their enemies lies in the possession of power to escape their +attention. Two different factors may contribute to this end. The first +of these consists in the practice on the part of many animals of +remaining absolutely quiet in time of danger. This instinct seems to +be nearly universal. The first impulse of most animals upon +discovering danger is to remain absolutely motionless. The eye +detects, with ease, objects in motion. These same objects might +entirely escape attention were they quiet. A mouse could remain in the +corner of a room for a long time without attracting the eyes of the +occupants of the room. Let it but scamper across the corner, and at +once it is discovered. It is quite conceivable that early animals were +divided in the matter; that the impulse of some was to escape from +danger, while others, frightened by the presence of the enemy, +remained absolutely still. Each plan has succeeded. Those which, on +running, ran fast enough to escape became the parents of others like +themselves, led eventually to a line of animals in whose speed lay +their safety. Those, however, which attempted to escape, and failed +because they were not swift enough, had their line cut off, and were +thus less likely to be represented in the following generation. The +constant result of errors along this line would be to destroy the slow +and preserve the swift, and in the course of time it is quite +thinkable that only the swift should remain. As the movements grew +more and more keen, even the slower of these would pass out, thus +tending always to produce the succeeding generation from those who +were most rapid, and hence most likely to transfer to their children a +similar power. + +But there is another tendency of animals which leads them when +frightened by their enemies to remain quiet. If this impulse is obeyed +thoroughly enough, it is easy to see how the owner of this habit might +entirely escape detection by his enemy. Any restless animal unable to +restrain his nervous agitation naturally betrays his presence and is +picked off. The result of evolution along this line would be the exact +reverse of the preceding. Those that lay most absolutely quiet would +be the parents of succeeding generations, while those who were slow in +coming to rest, or were indifferent about remaining quiet, were picked +off, and their tendency eliminated from the future of the species. In +this way many animals have come to keep entirely quiet in the presence +of danger. It is not a sign of high intelligence. As a matter of fact, +it is rather a stupid procedure, so far as the animal itself is +concerned, but it is a preserving stupidity, and many animals have it. + +The "June Bug" (which is not a bug, but a beetle, and arrives in May) +has this interesting habit of keeping quiet. If in its flight it +strikes the globe of an electric light, it falls at once to the +ground, and remains perfectly quiet for a time. After a short interval +it recovers and starts out to regain its previous activity. But this +recovery is by slow stages, and the whole procedure on its part looks +exceedingly stupid. + +The little snake with flattened and expanded head, known as the +blowing viper, or puff adder, is one of the most amusing +representatives of the tendency to "play dead" that could well be +found. If you strike him the faintest blow with the lightest stick, he +at once goes into apparent convulsions, in which he seems to suffer +the greatest agony. Then, throwing himself upon his back, he, to all +appearances, yields up the ghost. If, however, you retire but a slight +distance and keep your eye upon him, you find that his ghost returns +after a comparatively short absence, and he slinks away out of danger. +This is the most effective exhibition of this kind with which I am +acquainted. + +As for the habit of "playing 'possum" on the part of our opossum, the +trick would seem to be particularly inane. The truth of the matter is, +what is attributed to an unusual brilliancy on the part of the +creature is positively unusual witlessness. The animal has an +exceedingly small brain, as compared with that of a dog of similar +size, and to anyone who knows brains at all this particular organ +would not be looked upon as furnishing its owner much ability. The +fact is that the opossum has exceedingly small wit, and this little +deserts it in an emergency, as a result of which he grows helpless and +motionless. This is often supposed to indicate great wisdom. There may +be wisdom in it, but it is the wisdom that lies back of all nature. It +certainly is not the wisdom of the opossum. + +Man himself possesses to a marked degree this impulse to keep quiet in +danger. The man from the country who is visiting the large city, +suddenly startled by the "honk" of the auto horn, finds his power of +movement promptly arrested, and he is not unlikely to be struck and +injured by the machine from which the city dweller would easily +escape. This is not particularly to the credit of the city dweller, +who, when in the country, may find himself similarly startled by the +sudden appearance of the calf, the pig, or the sheep. The bull, which +a country boy, accustomed to him from childhood, will drive with a +willow switch, is a source of terrified concern to the city man. + +While the trick of keeping quiet serves many an animal in time of +danger, there is another device for escaping attention, far more +common and widespread throughout the animal world. The eye does not +easily see an object if it is colored like the background against +which it stands. A host of animals find their main safety in being +indistinguishable in color from the surface on which they live. There +are many biologists who seriously question whether protective +coloration, as Darwin called it, is as effective as he believed it. In +some quarters it is the present fashion to doubt protective coloration +entirely. No one has yet shown any principles which will better +explain the great color scheme of the animal world, and until such +explanation is forthcoming I believe it will not be wise for us to +discard the idea of protective coloration. No doubt it has been +overworked by enthusiastic believers in its efficiency. At the same +time, to overlook it completely, is, I believe, to make a greater +error. I have little doubt that when the broader explanation comes, +which will satisfactorily explain the color scheme of the animal +world, the idea of protective coloration will be found, not so much to +have been wrong, as to have been but partial. It will be included +under the broader principle which takes its place and will not be +supplanted by it. + +The idea of protective coloration is that very many animals have +ordinarily come to be colored like the background on which they live. +The process has taken many generations, and is very slow, but is none +the less sure in the end. In most cases the animal is probably +entirely unconscious of this point in its favor, and usually it does +nothing to assist the deception. The result is none the less effective +because the animals themselves are unconscious of the process. The +cabbage worm is green in color like the cabbage. This does not mean +that it got green by eating cabbage or by longing for greennesses. +Through long years the enemies of the cabbage worm have been picking +it off the plants on which it fed. This does not imply that cabbages +as we know them are very old, but cabbage worms doubtless ate the +leaves of the sea-kale long before man had cultivated it into cabbage. +During all these years the enemies of the caterpillars, generally in +the shape of birds, have been assiduously gathering them up. + +When we see how much the various members of the same human family may +differ in complexion, how much the various pigs in the same litter may +differ in size and in coloration, it is easy to understand that among +these caterpillars which have eaten the cabbage there must have been +considerable color variations. I do not imagine for a moment that the +birds had any preference for any particular color in their cabbage +worms. They took every caterpillar they saw, but they naturally first +saw those that were least like the background on which they lived. +The only caterpillar which was effectively hidden from his enemy was +the one that was indistinguishable on the leaf. If it escaped in this +way, the probabilities are that it would produce young which would be +at least a little more likely to be green in color than the progeny of +its darker-colored brothers and sisters. By this continued process the +birds steadily weed out the darker-colored specimens. There would +result, in the course of time, a race of caterpillars, whose ancestors +for so many generations back had been light green in color, that there +is little likelihood of any of the older and darker forms turning up +again. In the course of time all dark tendencies will have disappeared +from the family and practically all of the group will be light green. +Any sport or variation in the shape of greater conspicuousness would +fall a quick prey to the enemy and its line be cut off forever. + +The same sort of activity has resulted in the peculiar green color of +the katydid. This creature lives chiefly upon the leaves of trees and +shrubs. This insect is so large that, even though it is leaflike in +color, it might still be conspicuous. As a result those katydids whose +wings were most like leaves in form were least likely to be picked up +by the passing bird. This sort of protective appearance is intensified +by exactly the same means as that which brought about protective +coloration. The katydid least leaflike in appearance was eaten first. +Thus those most leaflike remain until the last, and are most likely to +produce young. Again, it was not the fact that they lived among leaves +which made them look leaflike, but it is because they look like leaves +that they escaped being devoured. + +The katydid has materially assisted in its own preservation by being +active chiefly at night. In the daytime it keeps comparatively quiet. +Thus seated upon a twig, especially if hidden among the leaves, it is +almost unnoticeable. At night, however, it moves about more freely, +seeking its food and eventually its mate. At such times it becomes +distinctly more conspicuous because its wings are steadily fluttering. +The hind wings are filmy and are very light green. The creature looks +most ghost-like as it flies through the evening air. + +A very similar history lies back of the coloring of the ordinary toad. +Though descended from the frog, and originally a creature of the +water, the toad has long since adapted itself to live upon the dry +ground. It still produces its young in the water as it did when a +frog. Whereas the childhood of the frog, that is, its tadpole stage, +is very long and it assumes its adult form comparatively late, just +the reverse is the case of the toad. The young hasten through their +tadpole stage within a few weeks, and assume the shape of the parent +toad when about big enough to cover your little fingernail. Now they +leave the water and seek dry land. Naturally they make the change when +the land is damp, that is, after a warm spring rain. People seeing +these multitudes of little toads hopping around over a bare spot of +ground, and remembering the rain of the night before, insist that it +has rained toads. Of course it never rains down anything which cannot +evaporate up. The stories of showers of toads and of earth worms, with +an occasional fish, or even creatures of larger size, are all pure +myths. There are conceivable tornadoes after which there might be a +shower of such creatures, but at such a time it is likely also to rain +barn roofs and buggies. You may be sure that toads which come down in +the rain are dead after they strike the ground. + +The little toads started out, perhaps a hundred at a time, from the +small pool in which their eggs were laid. These creatures find dragons +on every side. The gartersnake comes along and gets his first toll; +the heron follows him and takes such as catch his hungry eye; the +turkey gobbles up his from what are left. By the time the toad-eating +creatures in the neighborhood have taken such as they found, there are +very few remaining. These doubtless have been left for a very good +reason, generally because they were not noticed. This was because they +looked like the ground on which they sat, and because they kept +perfectly quiet while the enemy moved about. This process has gone on +so long that the toad has come to be astonishingly well protected by +its resemblance to the ground. This likeness it intensifies by its +interesting habit not only of keeping entirely quiet, but of dropping +its nose to the ground, instead of sitting high on its front legs, as +it does when not in danger. + +I have noticed that if a snake and a toad be placed in the same cage, +when the snake approaches to capture the toad the toad drops into a +squatting position, and is very likely to blow himself up until he is +rounder in outline than he was before. Whether this is a deceptive +trick which makes him the more resemble a stone is more than I can +say. I do not remember having seen our eastern toad do it. I have seen +it happen a number of times in the laboratory of a Colorado +naturalist, and it is quite possible that in the open country more +sparsely covered with vegetation than is our ground in the east this +inflating device may serve the toad more effectually than if it kept +its own outline. + +Even among creatures far more active than the toad and the katydid an +inconspicuous color must certainly result in distinctly better +protection. Everyone knows the jay and the cardinal when first he has +seen them, if only he has a slight acquaintance with their pictures. +They are so conspicuous that we recognize them at once. More common in +my region than the jay or the cardinal is the red-eyed vireo. This +creature moves industriously in and out among the leaves of our trees. +It is persistently in motion, is nearly constant in song, and is a +bird of fair size, being larger than our English sparrow, though +smaller than a robin. Many a nature lover will recognize twenty-five +or thirty birds at sight without any difficulty, and not know the +vireo. Yet the vireo is more common than two-thirds of the birds he +knows. There can be but one reason for this; the bird is +inconspicuous. The olive-green of its back, with its light under +parts, serves to hide it completely amid the foliage. Even the +bird-lover learns to find it first by its jerky song, and then by +watching for its movements among the leaves. + +One aspect of protective coloration has been brought to our attention +by the artist, Mr. Abbott N. Thayer. He first clearly explained why it +is that animals are usually so much lighter on the under side than +they are upon the upper. Mr. Thayer proves his position by taking some +ordinary cobblestones and painting one of them a uniform color and +placing it upon a board painted the same color. One would think the +stone would be inconspicuous; as a matter of fact, is quite easily +seen. The underside of the stone, turned away from the light, is so +shaded as to mark a distinct boundary between the stone and the board. +Another cobblestone was colored on its upper side like the board, but +the color faded into a lighter and lighter tint until the bottom of +the stone was nearly white. This stone, placed upon the board, was at +a short distance nearly invisible. In other words, although the +pigment was actually lighter on the under side, it was so much less +intensely illuminated, that the result was the same in tint as the +other side under the clear sharp light of the sky. + +Many a person, looking down into the water from a bridge, sees nothing +whatever of the fish in the water below, because their backs are +exactly like the bottom of the stream. Suddenly one of the fish, by a +quick movement, turns its lighter under side over in such a way that +it is clearly illuminated from the sky. Immediately a flash as of +silver strikes the eye of the onlooker and makes him aware of the +presence of the fish which had previously been undetected. If rendered +thus suspicious, the observer will carefully examine the bottom of the +water, he may quite likely find dozens of fish which had previously +escaped his attention. + +Nature is very versatile. So many of her apparently chance ventures +have proved successful that she has retained many devices by which her +children may be safe. One of these, which is doubtless often quite +effective and may serve to save an animal's life, is that of being +able to emit an odor so nauseating as to offend the enemy's sense of +smell, and doubtless remove the keen edge of his appetite. It is not +uncommon among the group of insects properly known as bugs to possess +an exceedingly unpleasant odor. Anyone who has handled a squash bug +will know exactly what I mean, and there are other members of the +group not so common as the squash bug, which, at least to the human +nose, are distinctly offensive. Some of the beetles also save +themselves by this device. + +One of the most interesting developments of this peculiarity is found +in the case of the common skunk. This creature has in each groin a +gland capable of secreting a highly offensive fluid. Ordinarily this +liquid is kept safely within its sac, and for a long time none of it +may escape. When closely cornered, the skunk will turn its tail toward +the enemy and with a quiver and a flip of his tail it can guide the +openings of two little tubes that come out along the root of the tail +in such fashion as to eject the fluid in a fine and foul-smelling +stream against the animal from which the skunk would escape. Once +fairly hit by this fluid, I imagine most animals will drop the skunk. +A dog surely will, and will hate himself for having made the attempt +to capture anything which must be so ignominiously allowed to escape. +If ones clothing is well saturated with it, it is nearly useless to +hope to remove the odor. A dog will carry the smell for several weeks. +For a long time it will be so strong as to make him an unfit denizen +of the house. Even swimming in deep water does not remove it. After +two weeks, although he may seem to be practically free from the odor, +a light rain will bring it all out again and make him nearly as +offensive as before. + +Not as prompt in its action, but in the end nearly as effective, is +the protective device which the toad sometimes uses to his distinct +advantage. May I be pardoned a personal account of this particular +feature. It was my good fortune to be for a short time a student in a +class taught by Edward Drinker Cope, one of the most brilliant of our +American biologists. Prof. Cope mentioned in class the fact that the +Batrachians (the group to which the toad belongs) have in many cases +the power to emit from their skin a fluid which is sufficiently +nauseous to deter an animal from eating the creature that secretes it. +Upon such authority as this, I had no hesitancy whatever in repeating +Cope's statement. One morning I had a class in the field studying the +ground ivy, whose dainty blue flowers were lifting themselves out of +the dewy grass. While we were thus engaged, a toad joined the circle. +He came out of his dewy retreat clean and fresh from his morning bath. +I took him in my hands, and made him the subject of an immediate +lesson. I showed to my pupils his eyes and his interesting method of +handling them, his tongue and its strange insertion; showed them how +to look into his mouth and look up his ears to his ear drums, and +pointed out many other interesting facts. Then I told them how Cope +had said that the toad had power to emit from its skin a fluid so +nauseous that many an animal hesitates to eat it. This is the first +peculiarity I had mentioned which I had not myself observed, and a +scientific qualm came over my conscience. Why had I never verified +this statement which I had so frequently repeated? On the impulse of +the moment, with the bright, clean skin of the creature fresh from the +dewy grass, making it less than usually repulsive, I ran my tongue up +its back only to find that it had no taste whatever. I was of course +surprised, but I was not foolish enough to deny, as the result of one +observation, the statement of a good scientist. The observation, +moreover, was one which I naturally did not care to repeat with any +frequency. Of one thing I was sure, toads do not always have an +unpleasant taste. + +A year later I had a class down by the side of a neighboring pond. The +pool was not an attractive one, and I had picked from it a more than +commonly unappetizing looking toad, which proved to be a mother which +had not yet laid her eggs. As I held her in my hands and exhibited her +various points to my pupils, I told them of Prof. Cope's statement. I +also told them of my unsuccessful attempt the previous year to verify +the statement. I added, however, that I would not repeat this +experiment on this unappetizing specimen. Hereupon the toad not only +exuded, but squirted, from a gland over her left shoulder blade a +fluid, milky-like in appearance, and forming a jet as thin as a +needle, but ejected with force enough to strike my face, which was at +least fifteen inches away. I moistened my finger on my tongue, lifted +the fluid from my cheek, and tasted it. Cope was right. A toad can +exude a most nauseous fluid. Horsechestnuts extracted and distilled +might possibly provide something as bitter. Why did I not find this in +the preceding case? I have too few observations on which to base a +conclusion, but I have a suspicion as to the reason. In the case of +the toad which spurted the fluid in my face, we had a creature with +whose life were tied up the lives of her many offspring, to be +produced from the eggs she was so soon to lay. Under conditions like +these, nature is more than commonly careful of her children. Whether +this be the reason or not, toads do not always have an unpleasant +taste, but when they do it certainly is most unpleasant. + +There remains to be considered the most effective plan yet mentioned +of escaping the enemy, and that is of really escaping. In all the +devices we have considered thus far the enemy is eluded. When the +creature lies quiet, or finds safety in its protective coloration, or +in its bad taste, or unpleasant odor, it still remains in the presence +of the enemy. A more progressive plan altogether is to escape the +enemy by flight. The great advantage of this plan lies in the fact +that the acquisition is valuable for every purpose. The creature then +can escape the enemy, can range widely for food or for a mate. This +gives it an enormous advantage in the struggle for life. The power to +fly, in insects, was doubtless originally gained in the attempt to +escape the enemy. Among many of the lower animals it is nearly the +only purpose that flying serves. Later on it enables the animal to +pass from one food locality to another. In a few creatures it plays an +effective part during the mating season. These last are probably both +derived powers, and the original function was that of escape from the +enemy. The grasshopper has grown its long legs to serve him for +safety, and through them it is helped along, moving about chiefly by +leaps when it wishes to go any material distance. It is only toward +the very end of its life that the grasshopper has wings, and then they +serve probably to aid in the search for a mate. Among the birds flight +began simply in sailing out of the trees, into which the creature, +still half lizard, had crept to escape its enemy. The earliest bird +known to us had comparatively insignificant wings. There was really +more support in its tail than in its wings, and this would distinctly +indicate that it glided more than it flew. It had claws also upon its +wings, and it was probably the case that this creature crept into the +trees, at least in its earliest forms, and sailed down in a manner not +unlike that employed to-day by the flying squirrel. From such simple +beginnings came the wonderful power of flight in the birds. + +Among mammals the attempt to escape from the enemy has led to an +interesting development, which will be more fully explained in a later +section when we speak of the history of the horse. The early mammals +walked flat-footed, as we do on our feet and as the raccoon and the +bear do on theirs. Gradually, however, as their enemies became more +fierce and better able to injure the larger mammals, the latter gained +in power of flight, and this gain consisted first in rising from the +toes, lifting the heels completely off the ground. At the same time +the leg and foot were gradually lengthened. Doubtless in this way the +fleet animals, like the deer, the horse and the giraffe, first came by +their long legs. Constant elimination of the short-legged ones, by the +pursuing enemy, resulted in the selection of the long-limbed ones for +breeding purposes, and hence to the ultimate elongation of the legs of +the species. + +The method of escape from the enemy involves cowardice. "He who fights +and runs away may live to fight another day," and so it may be the +part of wisdom in the weak creature to escape from his enemy by +flight. It is a far more estimable process, from our standpoint at +least, to stand against the onslaught of the enemy and beat him upon +his own ground. This end is secured in many animals by acquiring horns +or by lengthening certain of the teeth. The horn is a very ancient +instrument of defense. When the reptiles ruled the land horns were not +uncommon. They consisted in those days of hardened scales, which +lengthened and fastened themselves over a core of bone. Such an +old-fashioned instrument, sometimes made of newer materials, still +remains the defense of a number of animals. The rhinoceros has upon +his nose a lengthened projection, which is what might not improperly +be called hair glued into a cone. This enormous horn is a frightful +weapon, both of offense and defense, and, when backed by the terrible +weight of the body of the rhinoceros, it can do as deadly work as +almost any instrument of destruction known to animals below the grade +of man. But, after all, this is an old-fashioned method, and the +rhinoceros is a relic. + +Among the carnivorous animals the teeth, which were developed first +chiefly for the tearing of flesh in its consumption, became effective +for their courageous owners. Because these tearing teeth are well +developed in the dog they have come to be known as canine teeth. +Usually where an animal can use its teeth effectively for offense or +defense, it is the canine teeth that are thus modified. The cat has +developed them better than the dog, and one of the cats of a bygone +geological period had canine teeth so magnificently enlarged and so +sharp at the back as to give this frightful creature the name of the +saber-toothed tiger. The long teeth in the upper jaws of the elephant, +commonly known as tusks, are not canine teeth. The elephant has +completely lost his canines. His tusks are his incisors, and they have +developed as have almost no other teeth in the mammals. + +These are only a few of the numberless devices nature has evolved for +furthering the success of her children. There are so many others that +to many of us they form almost the chief point of interest in our +study of a new animal, or our closer observation of an old friend. + + + + +CHAPTER V + +ADAPTATION FOR THE SPECIES + + +The strife, as we have described it thus far, is a purely selfish +struggle. Every point gained is a point favorable to the welfare of +the individual animal. But nature is uncommonly careless of the +individual unless the advantage gained is also of use to the species +as a whole. Very often the life of an animal ceases when provision has +been made for its young. The male garden spider may have a long and +dangerous courtship, in which the uncertain temper of his ladylove may +lead her to bite off four or five of his eight legs. But her +ingratitude is not yet complete. He may have barely accomplished his +desperate purpose of fertilizing her eggs at all hazards, when she +ends the process by eating him. The male bumblebee fertilizes the +female in the late summer and then dies. She does not lay her eggs +before the next season. So it happens that no bumblebee ever sees its +own father, and no father bumblebee ever sees his own children. In the +honey bee the male, which has been fortunate enough to fertilize the +queen, pays for his honor by death within the hour. Superfluous +bachelors, among the honey bees, when the bridal season has passed, +are driven from the hive to die of starvation. + +An animal need not always be successful himself, but it is more +essential that he hand down his successful traits to those who come +after him. It is more important for the future generation that an +animal should have had it in him to do great things, though he himself +really have never done them, than that he should have learned to do +great things on a meager original endowment. Not what an animal +accomplishes is important to his children, but what he has it in him +to accomplish. Accordingly Nature is full of devices by which those +who have proved their original endowment by winning out in the +struggle shall hand on this endowment to a subsequent generation. In +other words, Nature is anxious that they may successfully mate. Here +we are again on distinctly debatable ground. Darwin himself believed +thoroughly in what he called sexual selection. It is the essence of +this idea that the males and females have grown unlike, more +technically have developed secondary sexual characters, through the +choice of the mating pair. It would usually be the more serious loss +if accident should come to the female, for she may carry fertilized +eggs for some time. Hence, if both sexes may not become attractive, it +is usually the male that develops fine colors, ornamental appendages +or a captivating voice. + +An interesting reversal of this process has taken place in civilized +man. His more savage ancestor adorned himself more lavishly than he +permitted his mate to do. With the advance of civilization man has +undertaken to defend his own mate most valorously. The result is it is +safe for her to be beautiful. Under these circumstances, however, it +is more necessary to her welfare that her consort be vigorous rather +than that he be handsome. Hence in the human species beauty has become +the prerogative of the woman, and this is increasingly the case the +higher the civilization. Whether woman suffrage and self-support will +reverse this process remains to be seen. There are indications that +point that way. + +There are many biologists who are at present expressing serious doubt +as to the validity of sexual selection. As in the previous cases of +protective coloration, I believe it will be wise for us to retain, +even though with an interrogation point behind it, the idea of sexual +selection until such time as those who object to it have furnished us +with another theory which will more nearly account for the observed +facts. While entirely conscious of the possibility that there is a +weak spot in the theory, we will still tentatively hold to sexual +selection. The fact that beauty in women is so intensely attractive +to man, and that vigor and manliness in man are so attractive to +women, leads us to infer that among the lower animals, although of +course in a vastly less degree, vigor and beauty are also attractive. +The weakest point of the position lies in the fact that it probably +presupposes a higher degree of capacity for appreciation on the part +of lower animals than they possess. Those who deny the truth of the +theory laugh at the idea that a butterfly can see clearly enough and +care enough for what it sees to notice whether its mate has wings of +one type or of another. The size, number and position of the spots on +the wings of many butterflies are so nearly constant that they cannot +of themselves have been entirely determined by the choice of the +insect. Yet this may not preclude the possibility of the fact that, +while the spots were produced through some other agency, certain types +of them were selected by sexual preference. + +If attractive coloration is effective anywhere in the animal world, it +will possibly be found among the insects, but it is especially likely +to be found among the birds. Very many field workers in these groups +feel quite sure of the value of attractiveness. When butterflies chase +each other up and down, circling and doubling, following each other +for long distances, it would certainly seem as if they were pleased +with each other's appearance. Some naturalists, especially those who +have worked chiefly in the laboratory, insist that it is the odor, not +the color of these insects, which is attractive, and some experiments +which have been made would seem to point in this direction. But the +creatures experimented upon most carefully were night-flying moths, +and it is quite possible that the sense of sight in the night-flying +moths has lost its vigor. + +The great difficulty in understanding sexual attraction in insects, as +based upon beauty, lies in the undoubtedly lower development of their +nervous activity; in other words, in the apparent absence of anything +worth calling mind. I think no one imagines that a butterfly, looking +upon two other butterflies who are competing for her affections, +deliberates between them and determines to admit to the circle of her +friendship the more brilliantly colored male. Moths are so +irresistibly attracted to a light as to fly into it without apparent +power to withstand its influence. They repeat the flight again and +again until they are destroyed. If they react so vigorously to the +stimulus of the light, it seems not impossible that they may also act +vigorously to the stimulus of color pattern, and that the male most +beautifully colored, according to the nervous ideal of the female, +should win her unconscious regard. At least it is certain that, in +very many of the butterflies and moths, the attractive coloration is +chiefly displayed when they are moving actively about; and when they +alight and their enemies can the more easily capture them, they +conceal their brilliant colorings. Most butterflies are very brilliant +on the upper surface of the wings and very much duller on the under +surface. Hence in flight they show their colorings exquisitely, but +when they alight, and are thus more likely to be captured, they fold +the brilliant surfaces together in an upright position. In this way +not only is the dull side of the wings placed outward, but the wings +themselves are placed edgewise to the sky, and it is from this +direction that their enemies, the birds, are most likely to see them. +Once upon the wing these creatures display their beauty with much +greater safety because they can escape the birds very readily by use +of their exceedingly jerky flight. The butterfly's motion is as +irregular as any we have except the bat's. This eccentricity is one +great element in their safety, and makes it less dangerous for them to +display their attractive colorations. + +One very large group of the night-flying moths have been named the +"underwings," because of the fact that their hind wings are very much +more brilliant than the front, and in lighting they fold the dull pair +back over the bright, completely concealing them. These creatures are +in the habit of resting in the daytime against walls, or stones, or +the bark of trees. The similarity in color between their front wings, +which alone show while sitting, and the background on which they rest, +is most remarkable. One may pass them again and again, although they +are of considerable size, and not notice them at all. Once let them +display their hind wings and the brilliancy of their color always +attracts immediate attention. + +It is among birds, however, that brilliant coloration serves its most +effective purpose. The birds are alert, exceedingly quick of sight, +and are much more discriminating than insects in almost every respect. +It is not so impossible that these creatures might even voluntarily +prefer a distinctly more brilliant mate, though the voluntary +character of the process is not essential to its success. Men +certainly are constantly attracted to women for whose charm it would +puzzle them to account. If this is true with regard to men, it is +certainly probable that birds would be largely influenced by phases of +attractiveness, of which they were observant, but unconscious. + +Certain it is that in many birds the males are far more beautiful than +the females. Perhaps the commonest illustration, and, at the same +time, one of the best is found in the so-called red-wing or swamp +blackbird. The male of this creature is a brilliant black, excepting +that upon the angle of the wing, spoken of roughly as his shoulder, +though in reality it is equivalent to our wrist, there appears a +splendid orange patch with a border of lemon yellow. When he folds his +wing he pushes this colored angle of the wing so deftly under the +feathers of his shoulder as almost to conceal it. When in flight the +bird is exceedingly conspicuous, showing, with every bend and twist of +his body, his gorgeous epaulets. Meanwhile, the female is likely to +pass unnoticed. She is dull in color and streaked like the grass among +which she lives. During the mating season the male hovers about her, +swaying from side to side in such a way as certainly to make it appear +as if he realized his good points and was bringing them to bear as +effectively as he knew how. After his mate has nested and is rearing +her young, it would appear that the male uses his brilliancy to lure +the observing enemy away from the nest containing his wife and +children. + +Another illustration of the remarkable superiority of the male over +the female, in many parts of the bird world, is seen in the case of +the common barnyard fowl. The rooster is so much more gorgeous than +the hen that anyone reasonably acquainted with these birds cannot have +failed to notice the fact. In some of our modern varieties we have by +breeding colored them nearly alike. The original chicken is colored +much like the common Leghorns. Shades of red and yellow decorate his +neck and back, while the flight feathers of his wings and of his tail +and the sickle feathers which ornament the rear of his back and hang +over his tail are lustrous dark green. The hen meanwhile is very much +less brilliant in her contrasts. I shall speak more fully of this in +discussing polygamy. + +The attraction of beauty is not the only lure by which a creature may +win its mate. Sound may captivate as effectively as beauty. This is +true of insects as well as of birds. Certain insects at least advise +their mates of their presence by means of a sound which they emit. +This is particularly noticeable among the group of straight-winged +insects to which the grasshopper, katydid and cricket belong. The +grasshopper has a ridge on the angle of his wing and a roughness on +the side of his leg. When these two are rubbed together the result is +sometimes a fiddling, sometimes a snapping or cracking sound, +differing in different grasshoppers. I doubt not these sounds are +pleasing to the female of the species, for they are always made by the +male. The katydid, instead of fiddling in this way, has a sort of drum +on the angle of his one wing, which he can rub over a tooth in the +corresponding angle of his other wing, thus producing the familiar +"katydid" sound. I have never succeeded in making a dead grasshopper +fiddle, but I have long known how to make a dead katydid say "ka." +Quite recently I have added to my accomplishment in this respect and +can make it say "katy." The "did" part of the song still lies beyond +my power. The crickets produce their sharp notes in much the same +fashion as the katydids. + +One observer of the chirping of the cricket says that the pitch of the +song varies with the temperature. He has even worked out a formula by +which one can tell the pitch of the chirp, if he knows the +temperature, or, knowing the temperature, can determine the pitch. Of +course this is too mechanical; yet it indicates that there must be +considerable relation between the two; the warmer the cricket the +happier he is. + +It is the males among insects that chirp their love songs. The females +never answer them. There is a peculiar notion that the female katydid, +when thus accused of some offense, replies "katy didn't." The truth of +the matter is that no female katydid ever replied to the accusations +of her lover, if accusation it be. She is absolutely dumb, not having +the drum upon her wings with which to reply. She is provided with ears +wherewith to hear, and, strange to say, she keeps them on her elbow, +as does also the cricket, while the grasshopper has his ears upon the +side of his body. + +Everyone who lives in the country, or goes into the country in the +summertime, is sure to know the humming of the so-called locust. It is +an unfortunate fact that the word locust may have several meanings. It +is properly applied to one group of the grasshoppers. The creature +most commonly called a locust is a cicada, or harvest fly. When the +weather gets quite warm the cicada starts his love song. He has two +long flaps to his vest, and under each flap he has a vibrating drum +head. This is set shivering by a muscle on its under side. The female +cicada again is silent. + +It is among birds that the love song reaches its finest development. +It may consist simply of a little chirp as in the chippy. It may +consist of two notes of a different pitch repeated steadily, as in the +tufted titmouse. It may attain considerable variation, as in the +robin. But in the choir of our best singers, like the catbird, +thrasher, and mocking bird, there is unending variation of notes. It +seems almost impossible to doubt the charming quality of this voice +upon the mate. It certainly is chiefly confined to the mating season, +and is indulged in almost entirely by the males. This does not mean +that a male does not sing excepting when he wishes to charm his mate. +But the time when he is in his most exquisite feather and most +charming mood is the time when he sings most sweetly, and this is the +time when he is taking to himself a mate. The love joy may so +overcrowd his life that he sings much and often, but the increase in +its amount and character during the mating season seems to proclaim +its purpose beyond a doubt. + +In addition to the allurements above described there are certain +peculiar behaviors of the animal during the mating season which are +intensely interesting. Sometimes they consist simply of a wild +delirium of joy, which overpowers the animal completely and makes him +do wonderful things. Birds will fly with impetuous leaps in the air, +mount higher and higher, singing wildly, only to turn suddenly at the +top of the flight and drop promptly to the ground. I have seen such +ecstatic flights in the oven bird and in our rollicking gold finch. I +have seen a catbird on his way to a tree turn three somersaults, much +like those performed by a tumbler pigeon, after which he alighted upon +the bough. None of these acts seemed deliberately performed in front +of the females, but I have seen three or four killdeer parading in +most stately and precise manner, spreading their wings and fluffing +their feathers, performing a sublimated cup-and-cake walk amid a +circle of attracted females. + +Even our little English sparrow, as I have previously mentioned, +fluffs himself up and spreads his wings and prances around in front of +his presumably adoring ladylove. But the weirdest performance of this +sort I have ever seen is that shown by the male ostrich. When he +becomes excited, swaying his body from side to side, he sinks slowly +upon his knees, until his body touches the ground, his wings spread on +either side and the feathers fluffed up so as to show every exquisite +plume in all its splendid beauty. The long neck is laid back until the +head, which is doubled sharply forward, is pressed almost against the +back, and in this strange position he sways from side to side, +apparently utterly oblivious, for a time, of everything. After about a +minute of this performance, he seems slowly to come to himself and +rise again to his feet. Now he is particularly likely to make vicious +attack upon anything within reach. + +It is not only necessary that the animal should be able to attract a +mate. There may be more than one claimant for the damsel's affection. +In many animals we see provisions whereby the male may effectively +deal with his rivals. This is especially likely to be the case if the +animal be a polygamist. In every species there are produced about as +many males as females. If the polygamous habit leads one male to +gather about him a group of females, with whom he mates, it is evident +that he is displacing an equal number of rivals, and they are not +willingly displaced. Accordingly we find that polygamy is usually +accompanied by a belligerent disposition on the part of the males. In +our ordinary barnyard fowl this trait is very evident. The rooster not +only domineers over the hens, not only struts about among them in +stately fashion and gives vent to his feelings by his sonorous voice, +he must also drive away from the neighborhood any rivals for the +affections of his wives. Hence the rooster attacks upon sight the +neighboring rooster, and battles with him to his entire discomfiture +and sometimes to the death. + +Among the members of the deer family this particular phase of the +relation between the sexes has produced in the males, and only very +rarely in the females, the magnificent branching horns. These are +intended not so much as a protection against the enemy as for an +offensive weapon in the battle for the mates. + +Beautiful and stately as are these magnificent horns, they last only +for a part of the year. We begin to understand their meaning. When the +wolf is hungriest, toward the close of the bitter winter, the deer is +without horns. When the time for mating comes, the deer within a few +weeks grows his horns, which at first are covered with a plushlike +coating, known as velvet. After a while this dries and he rubs his +horns against the trees until they are clean and smooth. Now he is +ready for the battle royal. + +In the case of the fur seals polygamy has carried its specialization +of the males to a remarkable extent. The bull seals are several times +as large as the cows, and are provided with terrific canine teeth. +With these they battle with a violence that very often results in the +death of one of the combatants. A successful bull seal who has +gathered about him a cluster of seal cows is seamed and scarred with +the marks of his annual combats. + +One more type of adaptation can be profitably considered. Animals have +developed many devices which serve for the protection of their young. +The wonderful silk spun by the spider was evidently primarily intended +to serve as a covering for the eggs. Probably all of our spiders agree +in using the silk for this purpose. Many of them employ it for +practically no other, though there are half a dozen different uses to +which different spiders may put their silk. Under these conditions we +have a right to infer that silk was primarily developed as a coating +for the eggs. In the case of some of our spiders a little fluffy mass +of silk covers the egg, while a firmly woven sheet of silk covers both +egg mass and fluff, holding it flat against a wall or the trunk of a +tree. In some of the higher spiders, notably our bank spiders, the +silken covering becomes an effective cocoon, spherical in shape, with +a little opening at the top like the neck of a small bottle. The egg +cocoon is woven in a mass of tangled silk between the branches of some +tough weed which will be sure to outlast the winter. Into the egg +cocoon the spider may place one thousand or more eggs. Having thus +provided her children with a snug winter home, the spider dies. When +spring comes with the warm rays of the sun, the eggs hatch and the +cocoon becomes a creeping mass of minute spiders. At the time these +spiders appear there is nothing for them to eat. The obvious way out +of this difficulty is taken. At once there begins a progressive party. +Spider fights with spider, and the prize in each conflict is the body +of the victim, which is promptly eaten. The winners in the first round +pair off again, and a little later, as hunger drives them, another set +of combats comes on, resulting in another halving of the number of +spiders in the cocoon. This process continues until not more than +one-tenth of the original number of spiders remains. By this time they +have gained sufficient strength of leg and jaw, and sufficient +dexterity in the use of both, to make it safe for them to venture out +and try their fortunes among the accidents of a strenuous world. There +can be little doubt after this long process has worked its final +results which tenth remains. Chance plays but small part in this +game. It is the fittest that survive. When this procedure goes on +generation after generation, the result must necessarily be that the +spiders grow fitter and fitter for their work. This method is hard on +the little spider, but it makes good spiders. + +Most insects die before their eggs hatch; accordingly they can pay no +attention to their own children. Whatever arrangements are provided +for the safety and strength of these offspring must be provided before +they appear. About the only care the majority of insects take in this +direction is to see that the eggs are placed where the young shall +find food as soon as they emerge. Insects' eggs are very small, and as +a consequence the creatures which emerge from them are likewise +exceedingly minute. As a result they cannot be expected to hunt far +for their food. Different insects use different devices by which to +overcome this difficulty. The katydid, for instance, must die with the +approach of fall. Her children will not appear until the following +year. Her food consists of leaves, but to lay the eggs in such a +situation would be a fatal process, because the leaf will drop off +before the eggs hatch. Accordingly, the katydid lays its shield-shaped +eggs in a double row near the end of a young twig. Next year when the +weather is sufficiently warm to hatch katydids, it is also warm enough +to force the buds on the end of the twigs. When the katydids arrive +their jaws are young and tender, but so are the leaves upon which they +are born. Hence there is little difficulty on the part of the young +katydids in finding an abundance of food. By the time the leaves have +grown tougher, the katydid's jaws are stronger, and the leaves will +still serve as food. + +Everyone who is at all familiar with country life and gardening is +familiar with what is called the potato or tomato worm. It is a long, +green, smooth, caterpillar, as long and as fat as your finger and +provided with a horn upon his tail. The gardener may not know that +after a while this creature will burrow into the ground, and there +change into an oblong brown mass with a sort of a pitcher handle at +one side. Next year this pupa will split down the back, and from out +of the brown case will come a hawk-moth, which soon will fly with +rapidly quivering wings and feast upon the nectar of our moon flowers +or on that of the "Jimson" weed. Those who have cleaned these pests +from the potato or tomato vines will often have noticed one of them +covered with what look almost like grains of rice. This appearance +reveals an interesting story. Some time earlier an insect that looked +very much like a dainty wasp with a rather long sting in its tail +hovered over the caterpillar. This is the ichneumon fly. Eventually +lighting upon the caterpillar's back, it punctured the skin with its +sting, and deposited eggs within the caterpillar's body. These eggs +soon hatched and the little grubs worked their way through the body of +its host. The infested victim feeds upon leaves and fills itself with +rich food. These parasites eat the food, and, try as it may, the +caterpillar does not succeed in getting fat. After the grubs have +gotten their full growth, each of them eats its way through a little +hole to the outside of the caterpillar's body. Here it spins around +itself a little white case, and looks like a rice grain. As the +caterpillar moves about, these seeming rice grains are rubbed off and +fall to the ground. Next year there will come up new ichneumon flies +to sting fresh caterpillars and repeat the entire process. + +Another remarkable provision for the young on the part of insects is +seen in the behavior of the big sphex wasp, known as the cicada +killer. The cicada, it will be remembered, is what is commonly called +a locust. The cicada killer is a magnificent big wasp, whose body is +nearly an inch long, banded with black and yellow, while the wings are +colored a smoky brown. This muscular wasp digs a long tunnel eight or +ten inches deep, which ends in a slightly larger room. Having provided +the location, he now sallies forth in search of the cicada. The heavy +song of the male probably serves as a guide to the wasp in case of +scarcity of cicadas, but the killer has apparently little difficulty +in finding his prey. The wasp pounces upon the insect, and in spite of +its strength and the thrashing of its vigorous wings punctures it with +his sting again and again. The poison of the sting entering into the +nerve centers gradually paralyzes, but usually does not kill, the +cicada. Now the killer carries its prey home, pushes it to the bottom +of the tunnel and deposits upon it a single egg. The wasp closes up +the hole and leaves the place. When the egg hatches and the grub of +the wasp emerges, it finds a big cicada just at hand, upon which it +feeds. By the time the cicada is completely devoured, the wasp grub +has obtained its full growth. After a short period of development a +new sphex wasp is ready to work its way out of the tunnel, find a +mate, dig a hole, and safely provide for its own children. + +Still more remarkable adaptations for the care of the young appear +among the birds. Here the eggs are not to be deserted, but are to be +cared for until the young appear. These again must have attention +until such time as they are quite able to take care of themselves. The +birds are warm-blooded animals, and even their young, while they are +developing in the egg, are warm-blooded. Consequently the temperature +of the egg must be maintained evenly and uniformly, or there will be +no development. + +The fish may drop its eggs carelessly upon the bottom of the stream. A +frog may deposit them in a mass of jelly and leave them forever. A +turtle may bury its eggs in a sand bank and abandon them to their +fate. The warm blood of the young bird demands more attention than +this. Accordingly, the parent bird has learned to make for itself some +sort of nest, in which the young may be kept properly warm until they +are developed. The ancestral bird, who was to be the progenitor of the +entire bird class, must have had some very simple method of providing +a place in which its eggs might be hatched. As the descendants of this +original bird have passed into new situations, the various lines have +taken upon themselves different shapes until we have the multiform +birds of to-day. The habits of the birds have also varied. Each has +adapted itself to the situation in which it found itself, and no +adaptation has been more varied and effective than the adjustment of +the nesting site. Nests are found upon the ground, in the bushes, on +the lower limbs, in the crotches of the trees, in the trunks of the +trees, upon their very summits, and on the tops of inaccessible crags. +To every sort of situation some bird has been enabled to adapt itself. +This has made it possible for very many more birds to thrive than +could have found a place in the world, had they all lived upon the +same plan. + +In the case of the bank swallow his nest may be a very simple +contrivance, consisting only of a tunnel running back into a bank, and +widening at the back. Some material that will soften the bed upon +which eggs are to be laid must be placed in this cavity. The whole +home is a very simple and crude affair. But little better is the +arrangement which the woodpecker calls a home. This has been cut into +the dry wood of a defective tree. No woodpecker can make his home in +absolutely solid sapwood. Hence the first labor of the woodpecker must +consist in finding a place in which it can dig. If there is an old +stump of a limb sticking up, the problem is readily solved. Such wood +has no sap in it, and is brittle enough to be easily dug out. But, if +there be no such stub, the woodpecker will find a suitable place in +most trees. At some time or other almost every tree loses a big limb. +When such accident occurs there will always be in the old trunk a +region through which sap once went to this limb. This region, deprived +of its function, goes completely dry, like the heartwood of the tree, +and it is into such material as this that the woodpecker succeeds in +drilling his well-protected home. + +As birds rise higher in the scale the nest-building becomes a more +complicated affair, and after a while we find a well-woven substantial +nest, through which even the air will not chill the eggs enough to +prevent their hatching, while the warmth is supplied by the mother's +body. It is often a matter of surprise to many people that a bird +should contrive to build a nest so exquisitely circular. The trick, +after all, is not quite so difficult as it looks. The robin gathers up +a few sticks and places them as the beginning of the platform. More +and more are brought and woven into each other, making a framework +altogether too big for the nest. Then mud is brought and plastered +inside of this. With the plastering of this mud the careful +circularity of the work begins. Every time a little material has been +added the robin sits down in the nest and revolves her body, in this +way shaping the interior much as the potter shapes a pot. In the case +of the artisan, it is the pot that revolves. In the case of the robin, +the bird itself revolves. The effect is the same in both cases--a +circular vessel is produced. A little lining added to the interior of +the nest softens it for the reception of the eggs. In this exquisite +home the robin lays her eggs, and sits upon them until they are +developed enough to hatch, and then feeds the young until they are old +enough to feed themselves. + +Far more remarkable than any of the devices thus far described are the +wonderful developments which have come in the class of animals known +as the mammals. Here the most wonderful protection is made for the +care and feeding of the young. But this is to be the subject of a +separate chapter. + +As long as we thought of each sort of animal as being a separate +species shaped in the beginning by the hands of the Creator, each of +these devices seemed to us a new manifestation of the Divine +Providence, whose fertile planning had conceived so many methods of +providing for his children. Unconsciously we thought of God acting as +man acted. Each animal seemed a purely separate invention purposely +designed for an especial place. Now we understand the plan in creation +better, and see that each animal has come from another not quite like +itself, some distance back, and this from still another. Our +admiration for these devices as they arise through evolution is no +less, but takes on another form. + + + + +CHAPTER VI + +LIFE IN THE PAST + + +Anyone who earnestly studies plants and animals as they exist in the +world to-day cannot help wondering how the earth began and where it +got its life. This is the true end and aim of geological study. The +history of man seems to run back into a far distant and gloomy past. +Except for the poetical account in Genesis and the traditions of +various peoples throughout the world, real history fades away into an +earlier time of which there are no written records. When the delvers +in the Mesopotamian plain talk to us of kingdoms running back through +seven or eight or nine thousand years, we seem to be getting back to +the beginnings of things. But seven or eight or nine thousand years +are as nothing in comparison with the age of the earth, which runs +back into a past so limitless that no man can safely assign any set +figure to it. In a recent paper, Dr. Walcott, of the Smithsonian +Institution, says that the antiquity of the earth must be measured not +in millions, for they are too short, nor hundreds of millions, for +this carries us too far, but must surely be measured in tens of +millions of years. + +When we attempt to study the past we find its various epochs unequally +clear to us. In human history only quite modern times are absolutely +clear. The history of the Middle Ages is distinct enough for us to +build for ourselves a picture of the time with reasonable hope of +gaining a correct view of the state of affairs. Back of this comes the +long stretch of the Dark Ages, in which here and there we have bright +spots, but it will perhaps long be impossible to portray clearly the +life of the people. Getting back to the Romans, things once more +become reasonably plain, as is true also in the case of Greek history. +Back of this stretches the Egyptian with fair precision, and, older +than it, the Babylonian and Chaldean. But these past three have not +left nearly so definite an account for us as did the later +civilizations of Greece and Rome. + +When we try to go back of these we must change our method of study +entirely. Writing is absent, and all we know of earlier men must be +inferred from a few pictures that were daubed on the rocks or carved +in ivory or bone, from tools made of stone or bone, from a few metal +or stone ornaments, or from the bones of the men themselves. Even so, +the history fades out without telling us its own beginnings. It is +quite as impossible for history to write its origins as it is for man, +from his own knowledge, to describe his birth. + +What is true of the human story is quite as true of that of the earth. +Recent steps are very plain. We may read them with considerable +confidence. As we go deeper into the rocks and find older fossils, the +evidence becomes less certain. The animals differed enough from those +of to-day for us to be less sure what they were like. As we keep on +moving backward through time, and downward through the rocks, we find, +after a while, strata in which there are evidences of life that +existed long ago, but in which these traces are so altered that it is +impossible to tell what sort of living things existed; we learn only +that they were alive. Going back still further, these fade out. There +is no knowing when the earth began; there is no knowing when life +began upon the earth. It is not meant that men have not wondered, even +reckoned carefully, as to how long ago each of these events occurred. +Many speculations have proved entirely useless, a few remain as yet +neither confirmed nor disproved, and of such we shall speak. + +For the last hundred years the theory of the earth's origin suggested +by the Marquis Pierre Simon De La Place, of France, near the end of +the eighteenth century, has held almost undisputed sway among men who +were willing to consider the question as open to human solution. This +theory is known as La Place's Nebular Hypothesis. When men began to +study the heavenly bodies with the newly invented telescope, new ideas +naturally sprang up. Among the objects which the glass disclosed were +the nebulæ, which are great clouds of fire mist, glowing masses of +gas. They are scarcely visible to the naked eye, but are among the +most interesting objects in the heavens when seen through a telescope. +The other suggestive heavenly body was our sister planet, Saturn. +Besides having a full complement of moons, Saturn has around it, as +distant as we would expect moons to be, three great rings. These look +very much as if one's hat, with an enormously wide brim, should have +the connection between the rim and the hat broken out completely, but +the rim should still float around the hat without touching it and +should steadily revolve as it stood there. The rings of Saturn are not +solid like the suggested hat rim. They are evidently made up of a +great number of very small particles, each moving around the center of +Saturn. But the great cloud of them is spread out flat. At the +distance which Saturn is from the earth they look as if they made a +solid sheet. Furthermore, they do not form, as it were, one continuous +hat rim, but it is as if the rim were broken into three circular +sections, each bigger than the one inside it and separated from the +next by an area nearly as wide as the ring itself. + +With such material in the heavens to guide him, La Place suggested +that the sun had once been an enormous fire mist scattered over an +area billions of miles in diameter. This gaseous material, by the +attraction of its particles for each other, began to condense and +contract. When the plug is pulled from a washbasin the particles of +water, in moving toward the center, in order to get out of the basin, +invariably set up a rotary motion. As the particles of this diffused +nebula began to gather together they, too, gave to the mass a rotary +movement. This grew more and more rapid, with greater contraction, +until the particles on the outer edge of the rotating mass had just so +much speed that the least bit more would make them tend to fly off as +mud would fly from a revolving wheel. When this point was reached +there was a balance of forces which made the outermost portion remain +as a ring while the rest contracted away from it, leaving it behind. + +It was La Place's idea that this process had repeated itself, and ring +after ring had been left behind. Finally the sun condensed and grew +into a ball, occupying the center of the system. At varying distances +from it were to be found either rings or planets which had been formed +out of such rings. For La Place suggested that in a ring like this +the material could not be quite evenly distributed. While every +particle in the ring kept revolving around the sun, those in front of +the densest part were slowly held back by the attraction of the +thicker portion, while those behind it in rotation had their speed +hastened until finally all the material in the ring had collected at +one spot and a new planet was born. La Place believed that these +planets formed their moons in exactly the same way, and that Saturn +was simply a planet not all of whose moons had yet been formed. He +believed that this happy accident served to tell us how the universe +had been created. + +Of course, so detailed a theory concerning anything of which we know +so little has always had much ridicule thrown upon it, and yet no +truly competing theory has been proposed until very recent times. + +Within a few years a Planetesimal Theory has been announced, and is +gaining considerable prominence, although it is too early yet to say +whether it will supersede La Place's idea. In this theory, also, the +suggestion comes from the heavenly bodies. With the increasing study +of the nebulæ, many forms of these interesting bodies have been +discovered. A very common type consists of a great coherent central +mass, with two or more arms extending from opposite sides in the form +of a spiral. This is as if gaseous revolving nebulæ had come into +comparatively close proximity to a passing body. The visitor, by its +attraction, drew from the nebula a wisp of gas. The revolving motion +of the nebula gave to the attracted arm the spiral form. + +These twisted arms are not equally dense throughout, but have +thickened knots here and there in their course. The Planetesimal +Theory suggests that these thickened knots are embryo planets and the +central portion of the nebulæ an embryo sun. After all the material in +such a body has condensed either around the knots or about the central +mass a new solar system will be complete. As before stated, neither of +these theories can be said to be demonstrated. Each of them has points +in its favor and each has its difficulties. It is pleasant to know +what men have clearly thought concerning such questions, but for a man +not a trained geologist neither will carry much conviction. He will +still rest with his own early conclusion that whichever shall prove to +be true, for him his old formula is still valid, "in the beginning God +made the heavens and the earth." He will no longer think of God as +having shaped the balls with his own hand and thrown them into space; +he will no longer dream that it all occurred within a week not more +than six thousand years ago; but still to him will come the reverent +conviction that, whatever the plan by which it was accomplished, it +was still God's plan and God carried it out. + +Now that we have tried to stretch our imagination back to the origin +of our globe, the question not unnaturally comes to our mind, how long +ago did all this happen? Is there any possible means of telling when +the history of the earth began? All such attempts lead either to +indefinite or to uncertain conclusions. Each man who essays the +problem approaches it from a different side and ends with a different +result. But no matter what the method of approach, all are agreed on +at least one point, the enormous length of time, as counted in years, +through which the earth has lasted. + +One great mathematician worked on the basis of the rate of the present +cooling of the earth. Counting backward to the time when the earth's +surface must have been hotter, according to La Place's idea, he +decided that our globe has been cool enough for the existence of life +upon it for a period of somewhere in the neighborhood of one hundred +million years. Those who try to study the rate at which mud is being +deposited in our bays and at the mouth of our rivers, and who hence +try to deduce how long it has taken to produce the thickness of all +the stratified rock we know, arrive at a figure larger, rather than +smaller, than that mentioned above. The same is true of those who try +to count the age of the earth by the rate at which the present rivers +are carrying away their river basins, and hence who calculate how long +it has taken the rivers of the globe to wash away all the rocks which +it is quite clear have been carried out. Still others have attempted +to solve the problem by seeing how much salt the rivers are carrying +into the sea, and consequently how long it must have taken the sea to +become as salt as it is. A very late attempt has been based on the +alteration in the minerals that show radio-activity. Conservative +estimates, based on all of these, would give us a figure on which we +must not count with any exactness, but which will serve at least to +mark the present trend of opinion. We may put this figure at one +hundred millions of years. + +The following table gives us the names of the periods into which the +geologist has divided the past history of the earth. The first column +gives a simple name, which, in each case, is a translation of the +technical name the geologist gives to the era. This technical name is +also given in parenthesis. The second column shows the number of years +ago at which this period may be placed, while the third column gives a +series of names most of which are in use in geology and which are +intended to indicate the stage of advancement of the higher animals in +that particular period. Some of these names are perhaps giving way to +later terms, but all of them will be understood by any geologist. +Most of them will serve to keep very clearly before the mind of the +ungeological the period which he is studying. Like all such tables, +this must be read from the bottom up. This arrangement is used because +the oldest rocks in the series are naturally at the bottom and the +newest rocks are on the top, though occasionally a region is +sufficiently upset partly to reverse the order. + + TABLE OF GEOLOGICAL TIMES + + ------------+------------------------+--------------------------- + | MILLIONS OF YEARS AGO | STAGES OF ANIMAL + ERAS | (VERY UNCERTAIN) | DEVELOPMENT + ------------+------------------------+--------------------------- + | | Age of Man + Recent Life | | (Quaternary) + (Cenozoic) | 0 to 5 | Age of Mammals + | | (Tertiary) + ------------+------------------------+--------------------------- + Middle Life | | + (Mesozoic) | 5 to 10 | Age of Reptiles + ------------+------------------------+--------------------------- + | | Age of Amphibians + | | (Carboniferous) + Ancient Life| | Age of Fishes + (Palæozoic)| 10 to 25 | (Devonian) + | | Age of Invertebrates + | | (Silurian and Cambrian) + ------------+------------------------+--------------------------- + Dawn Life | | Earliest Animals and + (Eozoic) | 25 to 50 | Plants + ------------+------------------------+--------------------------- + +Having seen what the scientist supposes to be the method of formation +of the earth itself, it will be interesting next to consider what the +biologist surmises as to the origin of the life upon the earth. Here +again two explanations hold. The one, and distinctly the older of the +two, says that at some time in the far distant past, under conditions +which are rarely if ever duplicated, out of the lifeless material of +the globe were produced simple and low forms of life. These could not +properly be called either animal or plant, but partook somewhat of the +nature of both. Of this there is at present no evidence whatever. The +only reason we have for suggesting it is that, if we understand the +past conditions on the earth, there was a time when life was +impossible. Now we find life. Hence it must have arisen. This of +itself, of course, furnishes no proof, but leads us to try to imagine +how the transition might have come about. Every scientist who believes +in this form of origin holds that if the exact conditions are repeated +the result will occur once more. He may believe that no such +repetition is possible, but he is confident that, if it could be, life +would arise again from lifeless matter. + +This process of life arising from matter that is not alive is known as +Spontaneous Generation. Two hundred years ago it was supposed to occur +frequently. It was common belief that the beautiful pickerel weed +which borders our Northern lakes, after freezing, went into a sort of +protoplasmic slime out of which pickerel were produced. The eelgrass +of the river was supposed to yield eels in a similar fashion. The dead +bodies of animals were supposed to turn into maggots. Such crude ideas +of spontaneous generation are no longer possible. The whole science of +bacteriology absolutely presupposes the impossibility of spontaneous +generation in the flasks and test tubes of the laboratory. One or two +men of otherwise good standing in science still maintain that they are +getting new life in their own test tubes, but they fail utterly to +persuade the scientific world. I think it is a fair statement of the +position of science to-day to say that there is no evidence whatever +of spontaneous generation, excepting the presence of life upon the +globe. + +Not all has been said, however, on this question. The chemist is +learning in the laboratory to produce many substances which, until +very recent times, were produced only in the bodies of animals or +plants. Dye-stuffs were originally gotten almost entirely from animal +or plant material. At present the great majority of them are made in +the laboratory, and in not a few cases they not only imitate the color +of the older material, but actually have identically the same +composition and constitution. The laboratory-made material is exactly +like that made by the animals or the plants. + +The same is true with regard to a large number of the fruit flavors. +These are due to the presence of ethereal oils in the plant, and their +exact counterparts can now be produced in the laboratory, and can +serve every purpose of the fruit flavor itself. Alcohol has been +produced artificially, and alcohols, which nature never dreamed of +making, so far as we can tell, but which are made on her plan, are +manufactured by the chemist. Last of all, sugar has recently been +built up by the chemist, though the method at present is so expensive +that it cannot possibly compete with the production of the commodity +from the cane and the beet. As in the case of alcohol, all the sugars +that nature makes can now be made artificially, and others of the same +general plan which she seems not to have as yet devised can be +produced within the laboratory. + +Attempts have been made to manufacture proteids, but these have as yet +eluded the efforts of the chemist. He is beginning, however, to come +nearer understanding their composition, and when he once clearly +comprehends that he may be able to reproduce them. + +One of the German chemists is convinced that the nuclein in the +nucleus of the cell is not a very complicated compound. Under such +conditions it is not a matter of surprise that the physiological +chemist should be constantly dreaming that he may at some time produce +living matter in the laboratory. To the ordinary mind it scarcely +seems possible. We are so entirely sure that life is not amenable to +physics or chemistry that we can hardly conceive of the possibility of +its originating out of matter in the test tube. If it does so come, +and when it does so come, this will not prove that life is a less +noble and less wonderful thing than we thought. It will only prove +that chemistry and physics are more noble and more wonderful than we +dreamed. + +There is another way of approaching this life problem, though it seems +to be rather a begging of the question than a solution of it. Of +recent years it has been discovered that even the very low +temperatures obtained by evaporating liquid air, say three hundred +degrees below zero, Fahrenheit, do not kill seeds or spores of mold. +The space between the planets is undoubtedly extremely cold. We have +always supposed it to be entirely too cold for life to exist in it. +But we laid little stress on the fact because we had no thought of any +possible life existing there. But the discovery that seeds and spores +can live uninjured through extreme cold has led to an interesting +suggestion. This is that when the earth became adapted to the presence +of life it was infected by germs transported on meteors from some +other system. According to this theory, organic dust through space is +ready to infect any planet which offers the conditions under which +life may arise. Of course this theory does not explain the origin of +life. It pushes back that origin a little farther or supposes that +life is as old as matter itself. Again we may leave to the scientist +the discussion and the elaboration of this or any other theory he may +promulgate concerning the origin of life. When he has established +clearly the process and can produce life we will accept his +explanation; meanwhile, we will always be interested in his attempts +to solve the problem, but still our simple formula, "in the beginning +God," serves our present needs and will satisfy us better than any as +yet unverified hypothesis. + +When we find through scientific investigation how life arises we will +simply know how God created it in the beginning. + +The next step in the understanding of early life is to study under the +microscope the simplest forms which we can find in existence to-day. +This, while far easier of execution than the problems which we have +thus far considered, is still not without serious difficulties. But +every day brings us nearer to the understanding of the structure of +living things. Life the scientist cannot see. All he can study is +living matter. Whether life can exist separate from living things is a +problem outside the range of his, at least present, possibilities. +Therefore, concerning it he has no answer whatever to give. But when +we come to study living things we find that all life is associated +with protoplasm. This apparently foamy, jellylike, transparent +material is the only living substance in all the world. Animals and +plants are larger or smaller collections of the little masses of +protoplasm which we know as cells. The lowest animals are each made up +of but a single cell. This consists of a small mass of protoplasm +surrounded almost always by a thicker skin or covering, known as the +cell wall and enclosing a complicated kernel known as the nucleus. The +protoplasm seems to be the living substance itself. The cell wall is +not a simple dead scum on the outside of the protoplasm, but is itself +able to do certain things which can only, so far as we know, be done +by living substances. For instance, of two materials dissolved in the +water in which the cell floats, the wall may permit one to soak into +the animal and keep the other out. The one allowed to enter will +usually be found good to be used for food by the cell. The nucleus +seems to store within itself the record of its past history and thus +enable the cell to do in the future what its ancestors did in the +past. + +Such simple cells can exhibit in very low form all the activities the +higher animals show in much more elaborate development. A one-celled +animal can move about, can recognize the proximity of food, can engulf +its food and digest it, can build up its own substance out of the +digested food, can absorb oxygen, can use this oxygen in the burning +of its own substance to produce its own activities, can act in +response to sensation gained from outside, can throw off its waste +matter produced by its own activities, and can grow. When the proper +time comes its nucleus can split in two, the cell itself enclosing the +nucleus can separate into two cells, each of which can grow to the +size of the parent cell and repeat its life. This is as simple an +animal as we have yet discovered. Every kitchen drain swarms with such +creatures. On a summer day the stagnant pools are full of them. The +simplest microscope will show them clearly. This is life in its lowest +terms with which we are acquainted. With such life, it seems to us, +the animal and plant world must have started their existence, when +first the earth began to teem with living matter. + +If, then, we may form any judgment concerning the first living things +upon the globe by considering the simplest creatures that live here +to-day, certain facts seem clear. In the first place, life began in +the water, and for a long time was only to be found in the water. +Single cells are so small and dry out so easily that it is necessary +to their existence that they should be kept entirely moist by the +presence of water all about them. It is true many of them will stand +drying, but while they are thus dried they can scarcely be said to be +much more than just alive. They are utterly inactive, or, as we say, +they are dormant. In such conditions they become covered with a tough +skin, almost a shell, and their protoplasm is itself nearly dry. Under +these circumstances the life processes hardly continue at all. The +protozoa, as these small animals are called, tolerate drought for a +time; but they only live, in any sense worth calling living, when +water is abundant and is neither very warm nor very cold. It is safe +to say that the early life of the world formed in the oceans of the +time. So absolutely is the habit fixed upon cells of protoplasm that +even to-day the activities of the cells of higher animals depend upon +the presence of moisture. The cells of our own bodies are to-day +living, as it were, in an ocean. Everyone can remember far enough back +to recall some time at which a tear slipped from his own eye onto his +own tongue; we know our tears are salt. The tongue has tasted, +undoubtedly, the perspiration from the lip on more than one summer +day; this perspiration tasted as salt as the tear itself. The lymph +that constitutes the "water" of a so-called "water blister" is also +salty, and even the little blood one gets into his mouth in trying +nature's method of stanching the flow from a cut finger gives the +impression that it contains a little salt. Every fluid of the body is +salty, and every cell of the body is bathed in salt water. It is too +long since the ancestors of our cells swam in the seas of the Eozoic +time for us to assert with any positiveness that the ancestral habit +is responsible for this trait in the descendants. Sure it is that +to-day our cells, like their ancestors of old, live in water, and this +water is slightly salty--as were probably the Archæan seas. + +The geologist tries as best he may to build up the geography of the +earth in the past. He endeavors to judge from the rocks as he now +finds them, where the seas, the bays, the dry land, and the mountains +of earlier geological times lay. The present aspect of the earth is +very recent, and earlier ages must have shown an entirely different +distribution of land and water. The North American continent was +certainly very much smaller than it is now. The first known lands lay +close to the Atlantic seaboard and probably extended out into the +water some distance beyond the present shoreline. The stretch of +continent was narrow, and grew narrower as it went southward. In what +is now the Canadian district, a considerable expanse probably existed +in very early times. Then a great internal sea, shallower than the +Atlantic, stretched its unbroken sheet over almost the entire area now +occupied by the United States, while only a comparatively small hump +of earth, ending in a narrower strip, lay where the great Western +plateau now rears its enormous bulk. + +A large portion of the history of the North American continent, with +its developing animals and plants, is tied up with the gradual +shrinkage of this interior sea. Slowly across the Canadian district, +the Eastern and Western lands became connected with each other, while +the waters progressively were pushed down the continent, which was +steadily growing from the east and from the north, though less slowly +from the west, into this internal sea. To-day only the Gulf of Mexico +remains as evidence of the broad stretch that once extended through to +the Arctic Ocean and west beyond the present position of the Rocky +Mountains. + +How this great Eastern backbone of the continent was produced, what +sort of animals lived while these rocks were being formed, or whether +this preceded entirely the existence of life upon the earth, no man +to-day may surely say. In the oldest of the rocks there are beds of +graphite, from which lead pencils are made. This substance is believed +by the geologists to be, like coal, the remains of vegetable life. But +these early rocks have been so heated and baked, so twisted and bent, +that whatever forms of life they once held are now obliterated, or so +altered as to give us no idea of what may have been their character. + +So far as anyone can now see, this past history is wiped out forever +and it will be impossible for men ever to demonstrate the character of +this early life. Speculations, more or less certain, will arise. They +may, after a while, seem so clear as to receive the acceptance of the +scientific mind. Yet the truth remains that the early history of the +earth, so far as animals and plants are concerned, is probably lost +forever. + +The most striking feature concerning the earliest layers of rocks in +which good fossils are found abundantly is the complexity of the life. +With the exception of the backboned animals, every important branch of +the animal kingdom is represented, and it is just possible that we +have even earlier forms of the vertebrates themselves. This, to the +evolutionist, is very disconcerting. To find the great groups all well +developed at least twenty-five million years ago and to find only +fossils built on the same lines since almost nonplusses him. When the +geologist tells him what an enormous length of time preceded the rocks +in which he finds these fossils and how absolutely these earlier +strata have been altered by the later geological activities he easily +understands why it is impossible to find fossils in them. As a +consequence, the evolutionist is forced to believe that all the +earliest animals have left no clear traces behind them. Life as he +first surely knows it is already extremely varied and quite well +developed in some of its groups. The early animals were as well +adapted to the times in which they lived as are the great majority of +the animals of to-day. The reader must not infer this to mean that +the animals of those days were like our present animals. They were +not. No one traveling in a far country could find there animals as +strange to him as would be those of the earlier stratified rocks. In +these there were no fishes as we know them to-day, not a single member +of the frog and salamander class, not a reptile, not a bird, not a +mammal, and probably no air-living insects. It is highly doubtful +whether there was any animal living upon the land and breathing the +air twenty-five million years ago. + +We start our study, then, at the period known as the Palæozoic era, +the era of the ancient life of the globe, beginning twenty-five +million and ending ten million years ago. The first of the three +sections into which this period of life is divided is known as the +Silurian age, the age of invertebrates. The word invertebrate is an +unscientific but convenient term under which we embrace all the +animals below those having backbones. This period is called the age of +invertebrates because, although there is an enormous wealth of animal +and plant life in the Silurian, there are no backboned animals except +the lowest kinds of fishes. It was supposed for a long time that even +fishes were absent. Now we know they existed, but they were small and +inconspicuous. In this period corals were wonderfully abundant, +particularly in the great internal sea which spread over what is now +known as the Mississippi Valley. Everywhere over this region must have +grown in the shallow water great numbers of creatures called crinoids +or stone lilies. They were attached to the bottom by slender stems, +sometimes many feet long. These stems are jointed, and when they +became fossilized the sections were apt to separate, with the result +that over a wide area in the Mississippi Valley it is very common to +find these little segments which look not unlike checkers. At the end +of the stem was a rounded head, with a mouth at the top, and around +the mouth were branched, feathery arms. The creatures must have been +exquisitely beautiful, but they have completely disappeared from the +face of the earth, with the exception of a very few, found in the +obscurity of the almost fathomless depths of the great ocean. Here +they remain as peculiar relics, only preserved by the unvarying +conditions in the deep sea from the extinction that has met their +sisters. + +Those who are familiar with our seacoast will know an interesting +creature known as the horseshoe crab, or king crab, though in reality +it is not a crab at all. It is rather more nearly related to the +spiders than the crabs, though no one but a technical zoölogist could +possibly associate them together. The ancestors of these king crabs +were the finest and best developed animals in this early Palæozoic +time. These creatures had bodies jointed like the tail of a lobster. +They were wide and flat, instead of narrow and rounded like a lobster, +and each joint of the body was highest in the middle and distinctly +lower at the two sides, thus forming three regions along their backs. +This structure gives to these creatures the name of trilobites. These +animals were the kings of the early ocean. They had an interesting +habit of curling up nose to tail before they died, and, as a result, a +large proportion of all the trilobite fossils we find are curled in +this peculiar manner. + +After these forms the most abundant fossils we find in Silurian times +were creatures that at first sight looked as if they might be related +to the clams. These are known as lampshells, because one shell +projects beyond the other and curls up at the tip so as to resemble +the clay lamps which are dug out of old Roman towns. The lampshells +also have nearly disappeared in modern times. Simple creatures +belonging with our present crab and snail had begun to make their +appearance, but they were not as abundant as we find them later on. + +The third group of the mollusks to which the nautilus and squid of +to-day belong is very abundantly represented in the Silurian by +fossils with coiled-up shells. As for the plant life of the time, it +is exceedingly difficult to say much about it. There must have been +nothing but marine plants, and these must have been on the general +line of the seaweeds. Little can be definitely said concerning them. + +The next period of the Palæozoic is known as the Devonian age, or the +age of fishes. Now the backboned animals first make their clear and +unmistakable appearance. There are remains in the Silurian which show +that there must have been a few fishes at that time. The Devonian is +so full of them and they are so well developed and so diversified that +this period is definitely known as the "age of fishes." They do not +closely resemble the fishes of to-day, but anyone would recognize most +of them for what they are. Their bodies were covered, not so much with +scales as with heavy plates, often arranged like tiles, those on the +forward half of the animal being often larger than those surrounding +the rest of the body. The creature was encased, as it were, in armor. +These were the rulers of the Devonian seas. The land, as yet, was +probably nearly without animal life, the creatures thus far being +almost confined to the water. A few insects make their appearance and +a few thousand-leggers are running around among the lowly plants; a +few spider-like animals have arisen; there are a few snails that have +left the water and taken to the land. Altogether only the dawn of a +land fauna is to be noticed. In the Devonian the plants are creeping +up upon the ground. Ferns are growing about everywhere, though they +are not exactly our ferns, but are rather a sort of intermediate form +between these and the present seed plants. + +Now comes an entire change in the history of the world. By some means +a rise in the bottom seems to have cut off a great part of the +internal sea from the outer ocean and to have converted it into a +widespread shallow bay, much like the sounds which lie back of the +islands that line the Atlantic Coast from New Jersey to Florida. Just +as this coastal region to-day is covered with salt marshes, so the +whole internal sea of the Carboniferous period was converted into a +great swamp. Sometimes an oscillation of the crust of the earth +brought this marsh above the surface of the sea and a luxuriant growth +of plants spread over it. Then a sinking of the bottom allowed the mud +and sand to wash down the shores, and spread out over the marsh, and +enclose the muck of the marsh under a layer of sand or clay. Another +lift of the bottom would start the swamp growing once more, and a +series of alternations between marsh land and sound seems to have +followed. The plants of this period are not the plants of to-day, +though we still have some very degenerate representatives of them. The +common horse-tail, with its angular, slender, leaflike branches and +its club-shaped spore-bearing body, is a modern degenerate descendant +of the treelike calamites of the Carboniferous forest. A creeping +evergreen, known by the name of clubmoss, is in like manner the modern +degenerate remnant of the scalestem and sealstem, which were the great +trees of the forests of the coal period. + +All over the surface of the marsh, between these big trees, grew the +ferns. While the coal itself was formed generally from the scalestems +and sealstems, the most common fossils found in the shales that lie +upon the coal beds are the ferns which covered the surface of the +marsh. + +It is believed by many geologists that this great luxuriant forest +points to a time when the climate was far warmer than it is to-day, +when the air was moist and heavily laden with carbon dioxide, and when +a great mass of clouds practically enveloped the earth. In this way +only do most geologists account for the enormous wealth of vegetation +in the Carboniferous period and for the abundance of plants up to the +Arctic Ocean, of the kinds that now grow chiefly in the tropics. But +of recent years a few geologists point to the fact that the peat bogs +of to-day, which seem to be the beginnings of future coal deposits, +are found almost entirely in cold countries. Hence it is a serious +matter to attempt to describe the climate of any part of the +Palæozoic era. Certainly of the climate earlier than the Carboniferous +it is very risky to say anything definite. + +The forests of the coal period seem actually to have cleared the air; +at least now we begin to find creatures related to our salamanders and +frogs moving about among the stumps of the marshes. These amphibians +are evidently the descendants of some of the fishes of the Devonian +times. Among these fishes were some which bear a great resemblance to +a few found in South America, in Africa and Australia to-day, and +which we know as lungfish. Anyone who has cleaned our fresh water +fishes in preparation for the table will remember that inside of them +there is a long slender bladder filled with air. This bladder assists +in making the fish light, hence making it easier for it to support +itself in the water. In certain swampy regions these lungfish swim +freely in the water of the marshes. When the dry season comes, +however, the water evaporates, draining the marshes completely. This +would prove the death of most fishes. The lungfish have a curious +habit which keeps them over the dry season. They cover themselves with +a coat of mud, inside of which there is a lining of slime produced +from their bodies. In such cocoon-like cases they survive the drought. +The means by which they breathe during this dry season is +interesting. The swim-bladder which we have just described in other +fishes is, with this lungfish, peculiarly spongy in its walls, +presenting a large surface full of blood vessels which absorb the air +on the inside of the bladder. This air the fish changes with moderate +frequency, the result being that the swim-bladder serves him exactly +as the lung serves a higher animal. To this fact he owes his name of +lungfish. + +We sometimes gain much light concerning the past history of any +particular form of animal by studying the development of that animal +in the egg, or, in the case of the mammals, before birth. It is an +interesting fact that when the lung begins to form in the embryo it +starts as a simple sac which is an offspring from the gullet, and +occupies the position of the swim-bladder of the fish. This sac later +divides into two, and develops into the lungs of the animal. This +assures the zoölogist that the origin of the lungs in the higher +animals is found in the swim-bladder of the so-called lungfish. In +this Silurian time certain of these lungfish were perhaps trapped in +the basin in the marsh by the uplifting of the border. The waters +becoming progressively shallower and more crowded, these fishes took +to the land, their fins developing into awkward limbs which slowly +became more perfect. + +To state the fact in this simple fashion is to make it seem far less +probable than is really the case. The simple forms of the life of +lowly creatures, as well as the simple character of the legs and feet +in the salamander class, make the explanation not so unlikely as would +at first sight appear. Suffice it to say that the scientist now +believes that out of the lungfish of the Devonian came the amphibians +of the Carboniferous period. + +At the end of the coal period came the greatest change the face of the +globe had seen for many millions of years. Slowly the continent rose +on both sides of the old interior sea. A great plateau formed in the +region of the Alleghenies and another in the western district, though +this latter uplift was to be completely washed away, and later to rise +again into the Rocky Mountains and the Sierras. With the uplift at the +edges of the continent came a steady rise of the internal marshes, +until what had previously been swamp land became progressively first +dry land and, in the western part, even desert, in that respect being +somewhat like what it is now. + +The amphibians of to-day (animals like the salamander and frog) all +lay their eggs in the water and their young have a tadpole stage. This +doubtless was true of the amphibians of the coal period. With the +beginning of the Mesozoic, or "middle life" period, a change and a +progression comes over the animal world. The tadpole life of the frog +is a rather lengthened one, while the toad has learned to crowd its +tadpole life within a few weeks. It would seem as if, in the earlier +times of the Mesozoic, this same change of habit had been going on. +With the drying up of the swamp, some of the amphibians crowded their +tadpole stage further and further back, until it was completely +accomplished before their young left the egg. An examination of the +development of the reptile in the egg will show a stage very similar +to the fish and to the amphibians, but this is all experienced before +the reptile emerges from the egg. The reptilian egg, unlike that of +the frog, is covered with a shell, packed away under the surface of +the ground, and left to its own fate. If, as most geologists believe, +the climate of the Mesozoic was distinctly warm, this habit of the +parent of forsaking the egg was not a serious matter. However the +creatures arose, it is certain that in this Mesozoic age reptiles +roamed the forests, swam the seas, and even flew in the air. Probably +at no other time in the earth's history has any one class of animals +so completely dominated the situation as did the reptiles of this age. +They were not only abundant; they were frequently enormously large. +Their skeletons are among the most interesting that we find to-day. +Gigantic lizards, seventy feet long and eighteen feet high at the +shoulders, dragged their heavy bodies through the marshy edges of the +lakes. Out upon the land others, not quite so heavy nor so large, +roamed about, some of them feeding upon the soft vegetation, others +having teeth fitted to tear down their herbivorous cousins. In some of +them the hind legs and tail were very heavy and the front legs so +light that it is quite clear they must have hopped around as do the +kangaroos to-day. Others of these reptiles went back to the sea, lost +the leglike development of their limbs and regained the flipper form, +though the bones of the fingers and toes are singularly +distinguishable in the paddle. + +Strangest of all, a considerable group of these wonderful reptiles +lengthened their little fingers, sometimes to three or four feet in +length, and had a skin stretched from these fingers over to the body +in such a fashion as to give them wings not unlike those of the bat. +In the wing of the bat, however, four of the fingers of the hand run +through the membrane and support it. In the pterodactyl, as these +flying reptiles are called, the middle finger supports the web, while +the remaining fingers can still be used to clasp objects or serve the +animal to lift himself, as the bat can do with his thumbs. + +Meanwhile an entire change is coming over the plant world. The last +third of this age of reptiles is known as the Cretaceous or chalk +period. Now, for the first time, the forests begin to take on more of +the character of our forests of to-day. Plants like our willow and +beech, poplar and sassafras appear in great abundance. Their broad +leaves serve better than those of any earlier plants to catch the +sunlight. But in addition they offered such effective evaporating +surface that they cast off rapidly the moisture obtained from the +ground by the plant. Accordingly in the winter season, when the water +in the ground is frozen and not available for plant purposes, they +were forced to throw away their leaves. It is quite possible that up +to and including the time of the Carboniferous, plants were all +evergreen. There had been before this little variation in climate over +the globe. Life in the Cretaceous begins to take on distinctly its +modern form. + +Among the reptiles of the forest there appear to have been a few small +creatures which to an observer of those times, if there could have +been an observer, would have seemed of the utmost insignificance +compared with their giant cousins. + +These little creatures climbed up into the trees to escape their +enemies. There were some in whom the skin, in front of the elbow and +behind the wrist, was loose, and stretched across the joint a little +like the wing of a bat. This reptile, climbing into the trees to +escape its enemies, found that this loose flap of skin served it +nicely, and sailed out of the trees in a manner not unlike that of +the flying squirrel of to-day. Among these experimenters in aviation, +certain forms produced scales which became elongated and finally slit +up along the side. These slit scales slowly developed into the +feathers of the birds of to-day. Whether the steps by which the change +occurred have been correctly stated or not, the result is sure. In the +rocks of the chalk period we find the remains of an interesting +creature. If nothing but its bones had been found it would have been +called a reptile. It had a long tail, it had claws on its front limbs; +it had teeth in its mouth; it had a flexible backbone. All of these +are reptilian rather than bird characters. Yet on the rocks +surrounding these bones are the unmistakable impressions of the +feathers of the wings and of the tail. Nothing in the world to-day has +feathers excepting the birds, and in this "ancient winged thing," for +this is the significance of its name--archæopteryx--we have perhaps +the most remarkable link in the world between two distinct sections of +the animal kingdom. Here is a creature half reptile, half bird; +perhaps one-third reptile and two-thirds bird. It was about the size +of the crow. A little later unmistakable bird skeletons will appear, +but still their jaws are provided with long conical teeth. + +Still more interesting from our standpoint is another set of primitive +animals, utterly insignificant in appearance, but of momentous +importance on account of their later history. Among these reptiles +were a few small creatures perhaps not much bigger than mice or moles. +Their teeth were a little more complicated and specialized than the +teeth of their reptilian cousins. Between their scales were small and +sparse hairs. Almost nothing but their jaws remain to-day to tell us +anything about them. But in this humble little creature of the +Mesozoic, utterly insignificant beside the tremendous reptiles of the +time, we discern the ancestor of the mammals. These were the +progenitors of the horses and cows, of the cats and dogs, of the +monkeys and apes, of the men of to-day. + +During this chalk period, which forms the last portion of the age of +reptiles, life for the first time grew to look much as it does to-day. +Now, apparently, the cold of winter and the heat of summer followed +each other in regular succession. There have been colder and warmer +periods at various times in the previous history of the earth, but +undoubtedly they were more uniformly cold or uniformly warm than now. +Ages were warm, or ages were cold, but now the earth clearly shows the +annual alternations of summer and winter, and for the first time +clearly shows the bands of climate on the earth which we know as +zones. + +In the chalk period this new factor of cold works mightily in favor +of the mammals. Their reptilian ancestors were cold blooded. When the +climate was warm they were active; when the climate was cold they were +sluggish. With the continuation of the annual alternations of cold and +warm weather that had now set in upon the earth, the little birds and +mammals had in their warm blood an advantage which, in the long run, +enables them not simply to compete with their reptile forefathers, but +to outdistance them absolutely in the race. Here and there, on earth +to-day, exist a few big reptiles like the crocodiles and the boa +constrictors. But they are few and comparatively insignificant among +the multitudinous population of the globe and are confined to the +hotter portions of the earth. For the most part, the reptiles now play +an insignificant and unobtrusive part. The little molelike creatures, +practically unnoticed between their feet in the later Mesozoic, have +come to supplant them entirely, and almost to rival them in size. +While the reptiles have grown steadily smaller, the mammals have +steadily become larger. + +While there is no land mammal to-day as big as the heaviest of the +reptiles in the Mesozoic, the whale, which is one of the mammals that +has again taken to the ocean, surpasses in size even those gigantic +creatures. There never lived in the world before a creature quite so +big as the biggest of our whales. Size, however, is not the most +important point in any animal. Speed, sagacity, variability, and power +of adaptation, these are the qualities which the world prizes, and +these the new mammals possessed. + +The next geological era is the Cenozoic, or period of modern life. +This is divided into two quite distinct sections, the Tertiary and the +Quaternary. This era began about five million years ago, roughly +speaking, and is still going on. The greater half of it is known as +the Tertiary. It was during this time that the mammals came to their +own. At first these creatures belonged to what the scientist knows as +generalized types. They are jacks-of-all-trades. The student of early +animal life finds in the little Phenacodus, which was scarcely bigger +than a good-sized setter dog, the beginnings from which many forms +have subsequently developed. This creature showed points of structure +which to-day may be seen in such diversified animals as the dog, the +horse, the rabbit, and the monkey. It is not, of course, suggested +that Phenacodus was the immediate ancestor of any of these. But there +were no animals in those times more like these I have mentioned than +was Phenacodus, and from forms like it in main features all of these +other animals have since been derived, each species of animal having +become adapted to one particular kind of life. The development of +diversified situations on the earth, the varieties of climate, the +variation between marsh and upland, between valley and plateau, +furnish a complexity of environment into each niche of which a new +form of animal fitted itself. + +With the increased complexity of mammals comes the submergence of the +reptiles and amphibians to-day. In all sorts of situations we find +mammals. The old-fashioned continent of Australia is separated from +everything about it by deep water, impassable to any animal which +lives upon it. In this secluded country evolution is very slow and +animals are very antiquated. We still find there mammals with the +ancient habit of laying eggs in a hollow in the ground, though after +these eggs are hatched the young are nursed on the milk of the mother. +But on the great continental stretches, where competition is keen, +where the animal must battle for his life against a wide field of +other animals, where migration into new situations is possible, the +rapidity of the development has been very much greater. + +It is in such a situation that man has arisen. In the extreme +southeastern portion of Asia, and on the islands lying close to the +coast, his highest non-human relatives, members of the ape family, +have reached their best development. These, of course, are not man's +ancestors. They are the less progressive members who are left behind +entirely in the race. Whether we have to-day any traces of the steps +by which man arose from the animal beneath him is vigorously disputed. +Eminent scientists will be found on both sides of this question. + +Many scientific writers to-day take it for granted that one form, +discovered in Java, while it may not be in the absolutely direct line, +must be very close indeed to the line of ascent toward man out of the +apelike forms. A scientist by the name of DuBois, working in the banks +of a stream in south-central Java, found a thigh bone which seemed to +him exceedingly human in its general character and yet not absolutely +like the human thigh bone. The oncoming of the rainy season raised the +water in the river so that DuBois could not continue his search. +Returning a year later, and digging back deeper into this bank, he +found a skull cap and two molar teeth which seemed to him to belong to +the thigh bone, although they lay several yards farther back, but at +the same level in the bank. + +When these bones were subsequently presented to a meeting of European +scientists by DuBois, he claimed to have found the "missing link" for +which there was so eager a demand. Some of the best anatomists of the +meeting, notably Virchow, laughed at his claim and said that the skull +cap was simply that of a human idiot, and could be duplicated in any +large asylum. A committee of twelve naturalists was appointed to +report upon DuBois' find. Of this committee three asserted the bones +to be those of a low-grade man, three insisted that they belonged to a +high ape, of a type somewhat higher than any we know to-day, but still +distinctly an ape. Six members of the committee of twelve agreed that +the remains were those of a creature higher than an ape and lower than +any normal man, and represented, in their opinion, a stage distinctly +along the line of development out of the apes and into man. + +This so-called "Java find" is known in science by the name of +Pithecanthropus, which means the ape-man. Whether we look upon this +fossil as a serious find or not, it is very certain that in the caves +of Europe belonging to the Quaternary period we find abundant +evidences of primitive man. The older these evidences are, the more +likely they are to be distinctly below the grade of man of to-day, in +the size and shape of the brain case and in the length and massiveness +of the jaw. + +There are probably more races than one represented among these skulls. +Some of them are surely well-deserving of the title of low brow. Their +heavy ridges over the eyes, their small foreheads, their massive, +heavy-set jaws show a race of men far less endowed mentally and much +better endowed in the matter of brute force than the men of to-day. +These skeletons, or parts of skeletons, are turning up every year, and +we are just beginning to know much about them. Capable men are +studying them with much care. The next fifty years may not improbably +make the history of the ascent of man as clear as is now that of the +horse, to which we shall refer later. + +The whole question of the descent of man from the lower animals, or +his ascent from them, as Drummond aptly termed it, is to most people +so entirely repugnant as to set them at once, and finally, against all +willingness to consider the question of Evolution. This, however, does +not solve the problem. Even though truth be horribly unpalatable, it +is still to be believed if it is only the truth. There is practically +no doubt left among scientific men of the origin of man in lower +forms. The evidences grow more and more complete year by year, and +from every line of investigation. Whether we study his anatomy, his +embryology, his history, his language, or his civilization, all +indications point in the same direction. Constant discoveries indicate +the fact of an enormously long development from a very humble form. If +this proves to be true and remains unpalatable, the fault lies in the +palate and not in the truth. Gradually we are coming to understand +that there is no reason why this truth should be unpalatable. We +consider a rise from humble conditions to be the glory of our heroes; +we esteem it an added charm in their strength that they should have +developed from untoward surroundings. It is not a disgrace to man to +have descended from the apes. It is to the glory of man that he should +have ascended from forms not much more promising-looking than the apes +of to-day. We must repeat, however, that the apes were the +unprogressive members, and hence we must not judge man's ancestors too +harshly. It must have been in them to rise. But the great glory in the +thought of the humble ancestry lies in the possibilities of his +future. If out of a creature not materially unlike the gibbering ape +of to-day there should have come, under the guiding hand of an +Almighty God, creatures with the endowments and capabilities of man of +to-day, then this is only an earnest and foretaste of that which may +be expected in the future. A time will come when man shall have risen +to heights as far above anything he now is as to-day he stands above +the ape. Even then there seems no end. With Infinite Power as the +agent, and limitless time in which to work, man would be limiting God +to an extent unwarranted by the history of the past to imagine that +His process had stopped to-day, and that man, with his many +imperfections of body, of mind, and of morals, should be the best that +is yet to come. There cling to him still the limitations and dregs of +his brute life. Often the brute in him comes to the surface. Little by +little he is coming to be dominated by the qualities God has last +given him. Slowly the brute shall sink away, slowly the divine in him +shall advance, until such heights are attained as we to-day can +scarcely imagine. As we can scarcely conceive the beginnings of this +process, so we can with difficulty imagine its end. This only can be +seen by the Eternal through whom it shall all come to pass, and by +whom all will in time be accomplished. + + + + +CHAPTER VII + +HOW THE MAMMALS DEVELOPED + + +When the idea of evolution first began to be much discussed, +especially after the publication of the "Origin of Species," there +were several points which appeared to be more than commonly difficult +of explanation. It did not seem impossible that the various types of +domesticated cattle should have descended from a common ancestor. It +did not seem difficult of comprehension that the dog might once have +been a wolf. Though not quite so credible, it did not seem absurd that +the tigers, lions, and leopards should have once all been alike. The +resemblance between these are strong enough to make the idea seem +conceivable. Though men were willing to concede this much, they +insisted that the great branches of the animal kingdom varied so +widely from each other as to make it certain that each was a separate +creation. It was particularly objected that the mammals differed so +entirely from other animals in several important particulars that a +special divine act was necessary for their appearance. The mammals +have a furry covering entirely different from the clothing of any +other animal in the kingdom, and have warm blood, which is found +nowhere else except among the birds. But particularly their method of +producing their young seemed so entirely different from that of any +other group that here a special creation was deemed absolutely +necessary. + +Other young creatures are produced from eggs laid by the parent and +subsequently hatched. The young of the mammals are born alive and +comparatively well developed. In addition, their first food, the milk +of the mother, is so entirely different from the food of any other +creature that this again seemed to involve a separate creation. +Gradually we have come to understand the whole matter of reproduction +very much better. Minute and careful dissections of rabbits, of dogs +and cats, of animals slaughtered for food, with occasional post-mortem +examinations of human beings in various stages of the development of +the young, leave us no longer in doubt concerning the main features of +the process. The better we come to understand it the more clearly it +becomes evident that in the development of the mammals we have no new +procedure, but, as in so many other activities, new developments of an +old process. + +There are two entirely different methods by which new animals and +plants may arise. One sees sometimes in the home of a friend a +geranium of particular beauty, the like of which he would be glad to +possess. The accommodating friend cuts a small piece from the +geranium. This is stuck into poor but well-watered ground, develops +roots, and eventually grows into a geranium stalk exactly like the one +from which it came and of which it is in reality only a detached part. + +In similar fashion, if one wants a particular kind of apple, he never +trusts to planting an apple seed. Going to the tree of the variety he +desires, he takes from it a small twig provided with a bud and inserts +this bud into a cleft made in the young branch of another apple tree. +The young bud so inserted starts up into a new branch, resembling +almost absolutely, not the tree which feeds it with sap, but the tree +from which the bud was originally taken. + +When we wish a particular variety of potato we obtain pieces of the +potato of the kind we desire. Each of these must contain an eye, which +is a bud of the old potato. When the sprout appears the new plant will +be practically identical in character with the plant from which the +potato was taken. This sort of reproduction, in which a piece of the +old parent grows up into the new generation, is called the asexual +method. But one parent is concerned in the process, and the offspring +are as nearly as may be like the parent from which they arose. + +The gardener who wishes to obtain new varieties is not content with +this method. If he plant the seed of the potato the outcome will be +most uncertain. His seed must be taken, of course, from the fruit of +the potato, and most of these plants never fruit. Every grower of +large quantities of potatoes will have noticed occasionally, on the +tops of the plant, after the flowers disappear, a globular growth +looking not unlike a small tomato, but with a tendency to become +purplish green in color. This is the fruit of the potato and in it are +the seeds. When these are planted all sorts of potatoes are liable to +start up. Most of them will prove worthless. An occasional seed may +produce an uncommonly fine plant. This new variety may thereafter be +propagated from the tuber, as the potato itself is called, and the new +strain will be kept constant in this way. This method of using the +seed for reproducing the plant is called the sexual method, because +two parents coöperate in the production of the seed. The pollen came +from one parent and the ovule, which after fertilization swelled up +into the seed, came from another. By this combination of two +individuals new varieties become quite possible. Nature seems to be +more concerned in improving her strain than in maintaining her older +strains. In all of her lowest plants and animals she uses the asexual +method of reproduction. As we go higher in the organic world the +two-parent method becomes increasingly common. When we reach the +higher animals, and most of the higher plants, this plan of double +parenthood, the sexual method, alone is used. + +In order that we may the more clearly understand how the mammals +produce their young and nourish them, we shall begin at the lowest +class of the backboned animals and note how the process is there +accomplished. As we pass upward through the kingdom the method +acquires greater complexity. When we finally reach the mammals, what +at first seemed an absolutely new process will prove to be, as is all +of nature's work with which we are thoroughly acquainted, but a +modification and an elaboration of some previously existing process. + +Some time ago I was passing the early months of summer by the side of +a lake in northern Pennsylvania. Near my tent, on the edge of the +water, was a wharf from which it was possible to look down into the +shallows about the edge of the lake. In early July the bottom began to +take on a strange appearance. Spots as big as a dinner plate became +evident because they were cleaned of the finer sand or mud which is +common on the bottom. A close examination showed that each of these +circular spots was being occupied and cleaned up by a sunfish. The +pebbles were lifted into the mouth of the fish and driven out again +with force. The water which emerged with the stones seemed to wash +away the dirt, while the pebbles themselves became gradually cleaned +of the green plant life which ordinarily covers them. After the +process was completed each spot was saucer-shaped and free from scum +and mud. Over each of these spots hovered the sunfish which made it, +and round and round the fish swam. The circles thus traversed were so +near each other that every now and then the occupants of two adjoining +nests would meet on the border. The fish which was most nearly on its +own ground would at once attack the other and drive him away. In a few +days the other partner in each family seemed to appear. Now two fishes +swam side by side over each nest, bringing the lower edge of their +bodies comparatively close together. In this position they moved +around over the pebbly bottom. The female was discharging her +multitudinous and very small eggs, so that they dropped to the bottom +of the nest. At the same time the male was expelling what in fish is +known as the milt. In this milt are the sperm cells of the male, each +consisting of a rounded head and a very slender body. These are +attracted by the eggs. Pushing up against them, the head of a sperm +cell, consisting almost entirely of the nucleus of the cell and +carrying the determinants which were to decide one-half of its future +characters, penetrated this egg and fused with its nucleus. This was +filled with the determinants of the characters inherited from the +mother. Of course many of the eggs, of which probably there are a +thousand, must have escaped fertilization. There are doubtless a +thousand sperm cells that went to utter waste for one which found an +egg to fertilize. These eggs nestled in the crevices between the +stones in the warm water of the edge of the lake. Here the sun could +easily penetrate to the bottom and hatch them. The little fish, still +guarded by one hovering parent, swam around in the water long before +the yolk of the egg, containing its large amount of food, had been +absorbed into the tissues of the young fish. This fatty store made the +abdomen of the fish in which it lay protrude enormously. Gradually the +fish grew larger and the yolk grew smaller until all had been +consumed. Soon the fish began to forage for himself and no longer to +demand or care for the company and protection of its parent. The +little sunfish is highly favored among his comrades in having any care +whatever by the parent. In the case of most fishes the female, +swimming slowly over the bottom, deposits her eggs, which are +fertilized by the male, which follows behind her. After the eggs have +thus been laid and quickened no other attention is paid to them by +either of the parents. + +Fish are stupid almost beyond the comprehension of those who are not +students of the minds of animals. Frogs and toads are a distinct step +in advance, and hence their mental activities play a larger part in +the process. + +In the love-making of the frogs and toads the song has an important +share. In each species the voice is a little different from that of +any other. In our familiar garden toad we have an excellent +illustration of the method common to the entire group. When spring +comes an impulse seems to stir in all the toads of a neighborhood. +Heretofore they have stuck faithfully to dry ground; now they start +off for the water. Whether their impulse is simply to move down hill +or whether they by some means detect the near presence of water, I +cannot say. Certainly a new fountain on a lawn will secure in spring +its prompt and full share of the neighborhood's toads. In any event +the toads of a district congregate in great numbers in any pond or +along the edge of any moderate stream. Within a short time their +flutelike, quivering voice is heard far and wide. That this note has +an attractive power over the female there is no doubt. She herself +makes no effort to imitate, but the song of her mate is persistent and +exceedingly sweet. I have seen a male sit upon a clump of grass and +utter his love call. Before he had been singing for more than half a +minute three females hastened toward him from a distance of perhaps +twenty feet. Each seemed anxious to reach as promptly as possible the +creature whose voice had proved so attractive. When the mating comes, +the female discharges a series of small shotlike eggs which are +encased in a very tenacious mucous. While they are being deposited the +male fertilizes them. No sooner have the eggs, fertilized by the sperm +cells, reached the water than the mucous at once begins to swell. The +result is that eggs appear encased in two slender strings of jelly, +each having a diameter about that of a lead pencil. At intervals of +not more than half an inch the shotlike eggs may be seen. The mother +toad, in laying these eggs, moves about rather restlessly in the +water. By this means she succeeds in wrapping the strings about the +grass and sticks of the pool. This will hold them quite safely even +against a considerable current of water, should the stream rise and +flood the side pools in which the eggs are laid. With this amount of +care, however, the attention of both parents to the young entirely +ceases. They are now abandoned to the chances of a fortune to them +exceedingly unkind. A toad will lay about five hundred eggs. It is +evident that on the average only two of these can attain maturity by +the time the parents have died, for the number of toads does not +materially alter season by season. The connecting string is made up +not of nourishment for the eggs, but of a bitter mucous so unpleasant +to the taste that fish are thus deterred from eating the otherwise +nourishing material. This secures for the young embryo a chance to +mature which in the absence of the jelly it would entirely lack. +Imbedded in this mucous is the embryo itself, surrounded by a small +amount of albumen and containing inside of itself a very considerable +amount of yolk. This gives to the egg a volume possibly a hundred +times that of the egg of the sunfish. Thus, even counting the care the +parent sunfish took of its offspring, which care is very uncommon +among fishes, the toad stands a distinctly better chance in life. The +protection of the bitter mucous and the large amount of yolk +permitting considerably larger development before leaving the egg, +give to the toad a material advantage. When the toad first emerges +from the egg it is amazingly like the fish. It has gills at the side +of its neck and swims by the movement of its tail. Later its limbs +develop, the hind ones coming first, its tail is absorbed, and it is +now a true toad, ready to leave the water. + +Altogether a higher state of reproduction is encountered when we reach +the reptiles, which are the next higher class of backboned animals. +Here very distinct developments of the process are discovered. The +turtle, to use the best known illustration, may lay but twenty eggs. +But she will not lay them at random in the water, as do the toads and +the fish. Each egg is wonderfully fattened with yolk. This means that +it is possible for the creature to develop to a far greater extent +before leaving the egg than was possible in the case of the toad. +Accordingly the little turtle, while it begins life not unlike a fish +and goes through the gilled and tailed period, during which it is not +unlike a tadpole, passes beyond this period before leaving the shell +and has already acquired its full turtle characters when first it +steps upon the scene. So big an egg as this would be highly nutritious +and animals would desire it immensely for food. Hence it becomes +necessary for the turtle to securely hide her eggs. In order to do +this, she scoops out a pit in the sand in which she deposits them and +here they develop. If no further provisions were made the eggs of the +turtle would dry completely and never hatch. Accordingly it becomes +necessary for the turtle to enclose each egg in a tough, leathery +membrane, known as the shell. Because the egg is thus encased it is +necessary for it to be fertilized before being laid. Accordingly the +male must place the sperm cells within the body of the female. These +cells swim nearly to the top of the tubes in which they are placed, +and there fertilize the descending eggs. Farther down the canal the +shell is secreted about the now swollen mass of yolk and white, +completing the egg just before it leaves the parent. + +If the evolutionist understands properly the line of descent, the +birds and mammals are both the descendants of the reptiles. While +there is less exterior resemblance between a chicken and a turtle than +between a cat and a turtle, the real relationship in the first case is +much closer than in the second. This is perhaps most easily seen in +the scaly legs of both bird and reptile. Another remarkable +resemblance lies in the fact that in both cases the eggs are large, +well stored with nourishment, and protected by a resistant shell. + +So few people know the turtle's egg that it will be better to describe +that of the hen, which it largely resembles. Underneath the hard shell +is a tough but flexible membrane which lies against the limey coating, +except at the blunt end, where a separation between the two gives room +for a bubble of air. Inside of this shell and its membrane lies the +white of the egg, which is nourishment for the chick, though not +nearly so rich as the yolk. This, besides the albumen which it +contains, is stored with large quantities of fat. It will be +remembered that upon breaking a hen's egg and dropping it into a bowl, +the yolk holds together because it is enclosed in a delicate sac. As +the yolk falls into the bowl there floats to the top of it a lighter +yellow spot as big as the end of a lead pencil. This is all of the egg +which thus far represents the chick itself. All the rest is +nourishment. This disk already consists of three reasonably +distinguishable layers of cells, which grow rapidly different from +each other. They spread and bend and twist, forming the young chick +and a set of organs which serve for its protection and maintenance +during its embryonic life. Within a few days these accessory organs +will have formed distinctly. Within the upper half of the yolk will be +found the small developing chick, which for the first thirty-six hours +of its development passes through a stage not unlike the fish, or the +earlier steps of the turtle. Within a few days it becomes clearly +evident that this creature is to be a bird, though it is much longer +before it is clearly a chick. + +This embryo is so soft that it is almost like curd in thickened milk, +and could be very easily destroyed were it not for a protective device +which Nature has employed. It seems necessary that it should be +protected with the utmost care. The matter will be better understood +if we recall a common experience. Almost everyone has tried to +dissolve some substance in water in a vial. If the bottle be filled +with fluid to the top and corked it is very difficult to shake up the +contents. Even vigorous agitation produces little movement of the +material on the inside. If we wish to shake up the solid with water +the bottle must be left partly empty. The brain of a human being is +protected by just the same device. If it simply lay within the skull +the first fall would mash the gray substance against the side of the +cavity. To prevent this calamity the bony case is made somewhat larger +in capacity than the brain itself, and the space between the two is +filled with a watery fluid. This serves to prevent jars and shocks. In +the hen's egg the same plan is pursued. The embryo lies on the inside +of a bag considerably larger than itself. This sac, called the amnion, +is filled with a watery fluid. With such a protection only the most +severe shock to the egg would sufficiently jar the embryo to do it any +harm. The ordinary experiences of an egg leave it undisturbed. + +Every living creature requires a constant supply of food and of +oxygen. The embryo is a living creature, and is no exception to the +rule. It needs an abundant supply of easily assimilated food and of +oxygen. When the hen's egg is first laid the entire contents, with the +exception of the little light-colored disk which floats on the top of +the yolk, form the nourishment. The disk alone is the living organism. +In the earliest stages the embryo receives its food by simple +absorption from the yolk. As the chick increases in complexity the +yolk at first grows swampy, with fluid trickling here and there +through the more solid portions. Thin walls form about these little +streams, thus producing blood vessels which cover the entire surface +of the yolk. These absorb the nourishment and turn it over to the +embryo. As the latter grows in size both the yolk and white diminish. +The embryo soon becomes larger than the remaining yolk and is attached +to it by a cord filled with blood vessels which enter the chick near +the center of its body. The abdominal wall has an opening at this +point. One of the later occurrences in the life of the chick, before +it breaks through the egg, is to have the last remnant of the yolk and +its sac slip to the inside of the abdomen, which then completely +closes over it. + +As yet, we have seen no arrangement for furnishing air to the chick. +At the same point at which the blood vessels from the yolk enter the +chick, another set of vessels pass in and out. These are attached to a +large flattened bag which floats above the embryo against the upper +side of the shell. This bag is called the allantois, and serves as a +sort of lung for the developing chick. The shell is porous enough to +allow air to pass through it. The blood vessels of the allantois take +in oxygen and give out carbon dioxide through the porous shell. The +blood thus altered is returned to the chick and serves its life +purposes. One of the reasons why the chicken must turn its eggs in the +nest is that, if the allantois remain too long in contact with the +upper shell of the egg, it will become attached to it and will not +thereafter perform its functions. + +The embryo thus enclosed in the egg finds its protection in the fact +that it is encased in a fluid contained in the amnion. It draws its +nourishment from the yolk upon which it lives and the nourishment is +transmitted to it by blood vessels. It draws its oxygen and throws off +its wastes through the instrumentality of the allantois, which covers +it over. Day by day the chick becomes larger, day by day it grows to +look more like what it is to be. By the nineteenth day it appears to +be complete. Its nervous organization is, however, not thoroughly +developed. If removed from the shell the chick still is indisposed to +stand upon its feet or to run about. If allowed to remain in the egg +until the twenty-first day, the chick will be able to push its beak +through the skin enclosing the bubble of air at the blunt end of the +egg and get the first breath into its lungs. Now it gives a faint +peep, breaks the shell of the egg, and steps out into the open air. + +I have given this somewhat lengthened description of the development +of the chick because of the light it throws upon the method pursued by +the mammals. The features which have been described in the case of the +chicken's egg could be as fully observed in the case of the turtle or +any of the other reptiles. Mammals are descended from the reptiles of +the Mesozoic, and whatever peculiarities there may be in their method +of producing their young must be derived from the reptiles. If we wish +to know how the earliest mammals produced their young, we can only +judge by the lowliest members of the group that live upon the earth +to-day. The most primitive of these is the so-called Duckmole, of +Australia. This little creature has habits not unlike those of the +muskrat. It burrows in the bank of a stream, and makes a nest at the +end of the burrow, where it lays its eggs. This is one of the very few +warm-blooded, hair-covered animals which still lays eggs. A little +higher in the scale stand the kangaroo and the opossum. These +creatures keep the egg inside of the body until it is hatched. But +this happens in so short a time that the young animal is exceedingly +immature and as yet unable to stand the outside air. Accordingly there +is a double fold of skin on the abdomen of the mother, covering her +breasts. This forms a suitable resting place into which these young +are conveyed as soon as they are born and from which they do not +emerge for many days. The little creature instantly fastens upon the +nipple of the mother, keeping its mouth constantly in this position. +At intervals the muscles of the breast force the milk into the mouth +of the young, which is still too undeveloped to suck for itself. As it +gets older the little opossum or kangaroo emerges from the pouch in +the pleasanter part of the day and in the absence of danger. It +returns to the mother's pocket as soon as it becomes cold or a cry +from its parent warns it of its defenseless position. + +These creatures are the lowliest of the class upon the earth. The +great majority of all mammals have elaborated a far finer plan, in +which the young are retained within the body of the parent until they +are quite able to stand the air. The length of this time varies in +different mammals from a few weeks to more than a year. The egg must +be fertilized before it leaves the body of the parent. If it should +fail in this it simply passes out and is wasted. If the fertilizing +cell reaches the egg before it has progressed far down the tube it +begins its development. The embryo forms for itself the sort of head +and tail and gill slits which would have served its fish or its +tadpole ancestor. Its limbs develop as little buds indistinguishable +from similar buds that would have formed fins for the fish or wings +for the bird. + +Around the embryo there forms a sac, the amnion filled with a fluid +which serves to protect the young mammals exactly as the growing chick +was protected. Under the forming creature there hangs a small but +empty yolksac. This is an actual remnant, a reminder of the past, when +the eggs of the mammals were also packed with yolk and the growing +embryo secured its nourishment exactly as does the maturing chick. But +a new method has been provided for the mammal, and consequently the +yolksac, though it has not entirely disappeared, has no nutritive +content for the growth of the embryo. + +The allantois of the chick now gains a new development and an altered +function. In the case of the chick it floats against the shell of the +egg and absorbs oxygen through the shell. Inside the body of the +mammal this is impossible, because the air is too far away. No shell +is formed about the egg because it is not to be laid. The tube of the +parent's body in which the egg lies becomes thickened at the point of +contact with the egg. It grows spongy and full of blood vessels. +Meanwhile the allantois is also growing spongy. These two tissues are +so closely pressed against each other that the blood vessels of the +transformed allantois mesh in with those of the thickened parent +wall. Thus the blood vessels of the mother are brought into close +contact with those of her offspring. Her blood seeps over into the +transformed allantois which is now called a placenta. From this it is +handed over to the offspring, which thus receives from the mother her +blood, and returns its own used blood for enrichment and purification. +So the allantois of the reptile has become the placenta of the mammal. +In the first instance it served only as an organ of respiration. Now +it has come to supply the embryo with rich blood containing both food +and oxygen derived from the mother. After the offspring is born this +thickened pad breaks loose, and subsequently is also extruded from the +body, forming what is known as the afterbirth. + +Thus far we have spoken of the change in the method by which the young +are brought to such a stage of development that they can stand the +outer air. One of the improved differences between the mammals and +other animals lies in the method by which they nourish their young for +some time after birth. The very word mammals signifies an animal who +is in the true sense of the word a mamma. This name for mother is +given to her because of the fact that she possesses what are +technically known as mammary glands, or, in simpler language, breasts. +It would seem as if here we had an entirely new organ. No other +animal gives nourishment to its young in such fashion; all mammals do. +What is the origin of the habit? How did the organ arise? + +A part of an animal's body that has the power to gather material from +the blood and pour it out in the shape of fluid is known as a gland. +Sometimes a whole organ does nothing else. Sometimes small glands are +scattered through, or over, the surface of another organ. There are +two kinds of glands in the skin of the mammal. The best known and most +frequently thought of are those which pour out the perspiration. These +have a double function. In the first place they assist in keeping the +temperature of the body uniform. When we are too warm they pour out a +watery fluid over the surface of the body. If the air is dry enough +and our body not too closely protected by clothing, this perspiration +passes off in the form of vapor. All evaporation requires heat, which +in this case is extracted from the body. So soon as the temperature +returns to its normal level the flow of perspiration ceases. The other +function of the sweat glands is to take from the blood some of the +waste matters of the body and pour them out upon the surface. This is +done in order that the body may free itself from substances which, if +they were to accumulate, would have a poisonous effect upon its +action. It is this function of the sweat glands which makes it +necessary for us to bathe the surface of our bodies with water. Dirt, +in the ordinary sense of the word, is not harmful to a sound skin. Our +reason for bathing is really to remove the wastes which we ourselves +have poured upon the surface of the skin. These, if allowed to remain, +soon decompose, like all nitrogenous substances, and become very +offensive. They may then be reabsorbed into the skin and nature's +effort to throw them off has been in vain. These glands, since they +contain waste matter, could not possibly yield food for the young. +They would poison and not nourish. Hence, whatever the breasts may be, +they are not altered sweat glands. + +There is another set of organs in the mammalian skin. At the base of +each hair lies an oil gland. The function of these is to pour out a +substance which spreads along each hair and over the surface of the +body. The outside of the skin is always dead, and would easily crack +were it not for the constant secretion of this oil. In winter, when +the blood circulates less freely and these glands consequently pour +out less oil, the supply frequently runs short. If what little is +poured out is too frequently removed by washing, the skin becomes +brittle, and, on bending a joint, the epidermis cracks. The gloss of +the hair is due to the oil thus poured out. This oil becomes one +ingredient in the milk produced by the transformed gland. But there +is another important constituent. When one does unaccustomed manual +work the ordinary result is the formation of a blister. The epidermis, +or scarfskin, becomes detached from the dermis, or true skin, and the +space between the two rapidly fills with the fluid portion of the +blood, known as lymph. The fact that no blood vessels have been broken +in this detachment results in there being no red corpuscles in this +fluid. Wherever a cavity forms in the body lymph is liable to enter +it. + +The milk glands of the mammals are modified oil glands. The fluid +which they now pour out is no longer exactly the old oil with the +addition of the lymph. Undoubtedly in the past the first milk was more +like this simple mixture. There seems no doubt that the breasts of +to-day are the enlarged and modified oil glands of earlier mammals. In +one of the most primitive of our mammals the young simply lick certain +bare spots on the surface of the mother's abdomen. As higher forms +arise there develops a smaller or larger mound with a distinct +projection, about which the lips of the offspring can easily fasten. +Lamarck would have said that the suction of the infant had produced +such a mound, and that this had been transmitted to later offspring +until it had grown to be the highly developed organ we now find, for +instance, in the cow. Since, however, we have come to disbelieve in +the transmission of acquired characters, this explanation will no +longer serve. We must content ourselves with saying that, by whatever +accident the nipple arose, the success of it when present determined +its selection by nature and its consequent persistence. With increase +in its function has come increase in the size of the glands. Lower +animals which, like the hog, produce a large number of offspring, +possess a large number also of these glands. With the diminishing +number of young and greater care of them as we rise in the scale has +come also a diminishing number of breasts in the female. Whether those +on the front of the body should persist, or those on the rear, depends +upon other factors in the life of the animal. Hoofed animals, perhaps +because their best weapon is the hoof and they can there best protect +their young, have retained them in the rear of the body. In the group +of animals known as the primates, including monkeys, apes, and man, +the habit of holding the young in the arms for protection has +determined the persistence of the breasts upon the chest rather than +the abdomen. + +It is interesting to notice that the habit of the elephant of +protecting its young by means of its tusks has also resulted in a +similar position of the milk glands. + +That the primates had once a larger number of offspring is confirmed +by double evidence. Even to-day the number of children at a birth is +often two, sometimes three, rarely four. The day before this was +written came the report of a case of five children at a birth, all of +whom seemed sound and all of whom lived. Still more direct evidence is +found in the fact that occasionally in the human female there are two +pairs of breasts, and very rarely three pairs. These are then disposed +in a double line down the front of the body. + +The new plan of caring for the young is one of the priceless heritages +of the higher animals. As we rise in the grade of life the number of +the young produced at one time steadily diminishes, while the care +spent upon them increases. The shad may lay four hundred thousand eggs +and trust them entirely to their fate. The sunfish will lay a +thousand, by no means all of which can be fertilized, but it guards +them somewhat after deposition. The toad lays several hundred, stores +them with a considerable amount of nourishment, and protects them by a +bitter deposit of mucous. The turtle has reduced the number of eggs to +perhaps a score. Each of these is supplied with abundant nourishment, +so that the young may develop to considerable size and activity before +emerging from the egg. This material is enclosed in a firm protective +shell and hidden away from sight by being buried in the ground. In the +mammals comparatively few eggs are produced at one time. These are +fertilized within the body of the parent, are attached to the parent, +and absorb her blood. No shell is needed because nothing will kill the +developing offspring that is not likely to injure the parent. Not only +do the young feed upon the blood of the mother up to the time of +birth, but they are practically dependent upon this same blood after +birth. Though they do not take it directly from the veins, the milk +is, none the less, the transformed blood of the mother. This assures +the young of food as well as of protection. Best of all, the young are +provided with the companionship of the mother. Now for the first time +animals learn by example. Heretofore they have been born with a nearly +undeviating instinct; now intelligence begins to arise. They can +imitate their mother. Heretofore no acquired characters affected the +young. In the mammals, although the young cannot inherit the acquired +habits of the parents, they can get them by imitation, which serves +nearly as well. + +There is, however, a more wonderful advantage that comes from the +close attachment between mother and offspring. This intimate +relationship brings about an affection of the mother for her young +heretofore unknown in the animal world. It is somewhat paralleled +among birds, but here the care of the nestling is less intimate, far +less maternal, than the care of the mammal for her young. As the +number of the young grows less and the care taken of them increases, +the intensity of the affection also increases. By the time we get as +high as the dog or the cat this fondness becomes a fierce, +self-sacrificing love. When we come to man, with his high intellectual +powers, with his deeper moral sense, we find a wonderful change. This +love of the mother for her child has grown into the finest emotion +possible to the human heart. It no longer is confined to the dependent +life of the child, but follows the offspring through its entire life, +guiding, guarding, shaping its destiny, handing on to the child the +treasured wisdom of the race. Influenced by the example of the mother, +the father comes to have a love for his children. It is not so strong +as that of the mother, nor so utterly unselfish, but it is still a +noble and exquisite love. Developing in a different direction, the +love of the mother for her children grows as civilization advances, +and spreads over the father of those children as well. Again +reflecting her love, the man finds himself filled with a new feeling +for the woman. It is never as unselfish, as free from desire, as is +her love, but it completely transforms his relation to her. What has +been with him simply desire is ennobled and enriched until it becomes +the finest passion of his life, absolutely transforming him, in +relation to her, from a selfish brute into a tender and life-long +companion. So utterly does the love thus engendered transfigure human +life that when we seek to express the divine nature in human terms, +and these are the only terms we know how to use, the richest +revelation that has come to us is the conception taught by the Master +that "God is Love" and that "as a father pitieth his children, so the +Lord loveth them that fear him." + + + + +CHAPTER VIII + +THE STORY OF THE HORSE + + +Ever since men have been familiar with the idea of evolution there has +been a temptation on the part of the zoölogist to draw up pedigrees +expressing the relationship between the various groups of the animal +kingdom. The impulse is natural, and, if the resulting tables are not +accepted with too much confidence, the result is not undesirable. The +truth of the matter is that all of these pedigrees are more or less +hypothetical. They simply show what connection seems most likely. In +all of them are spaces filled with doubtful names. Each addition to +our acquaintance with the past history of animals necessitates +revision of our tables. The student of fossils, trying to rebuild in +imagination the world of the past, finds himself often strangely +unable to link these animals together. The result is that the more we +know of fossils, the more distrustful we become of the easy +connections we have been making between groups. Accordingly we are +more than commonly pleased when we find the clear indication of a +genuine pedigree, actually illustrated by real examples, following +each other in time through the geological history. A few of these +lines are gradually becoming plain, and none of them is clearer than +the pedigree of our familiar and much loved horse. The example is a +particularly interesting one, not only because of our affection for +the animal, but because the horse originated in all likelihood in +North America on the land occupied to-day by our Western plains. As +though he loved the country of his ancestors, he returned after having +circled the globe, and once more went wild in the home of his +forefathers. The problem was first worked out in Europe and later +elaborated in this country. Now the history gets its finest expression +in the American Museum of Natural History in New York City. The +collection of fossil horses in that institution surpasses in +completeness and in excellence of mounting and of sympathetic +restoration any similar collection representing the ancestry of any +other animal in the world. + +In the table of Geological Times, given in chapter six, the era of +recent life known as the Cenozoic is seen to occupy something like +five million years. This figure, as was previously suggested, is very +uncertain, and may be three or may be six, but is safely represented +in millions. Through most of this time stretches what is known as the +Age of Mammals, the Tertiary Age. Its close, occupying only the last +few hundred thousand years, is known as the Age of Man, the +Quaternary. Through perhaps three or four millions of these years +stretches the known pedigree of the horse. + +When we go back to the early Tertiary we find a forest, with trees +that shed their leaves, interspersed with glades, in which already the +grasses were beginning to be developed. This state of affairs had +existed but for a comparatively short time, geologically speaking. It +had come only in the latter part of the preceding era. Lake and swamp, +meadow and forest intermingled to make a rich and varied scene. Slowly +the land toward the western side of North America lifted itself into +plateau and mountain range. Slowly the westerly winds began to be cut +off by the barriers thus raised across their path. As they swept over +the plateau and down into the eastern plain their moisture came to be +diminished. Gradually a very different state of affairs set in. The +ground became harder, the forest became sparser, the plants became +higher and firmer, the grasses tougher and more wiry, and, by the time +the Quaternary arrived, a condition probably even drier than that of +to-day existed over our western highlands. Throughout this long +change, spread over millions of years, a creature which has become our +horse steadily persisted and steadily advanced. Side lines developed +which finally disappeared, but the main line kept on, and when the +Quaternary came the horse arrived with it. Many of the skeletons in +this series were known before it was realized what they were. As time +went on and intermediate forms were found, it became possible to +recognize these as ancestors of the horse and to assign them their +proper position in the family tree. + +[Illustration: THE EVOLUTION OF THE HORSE'S FOOT + +_After H. F. Osborne and Charles R. Knight. By permission of the +American Museum of Natural History._] + +The earliest of the forerunners of the horse with which we are +acquainted would certainly not be recognized as such by any but the +most careful student of animals, if we could see him to-day. He stood +not higher than a fox-terrier dog, though his shape was very +different. But he would probably be more likely to be classed with the +dog than with the horse by the hasty observer, for he walked with four +toes of each foot upon the ground as the dog does to-day. Like the +dog, he had hanging at the inner side of his front foot a little +useless toe. He was long in body, comparatively short of leg, a little +long of head and neck, and distinctly long of tail. His grinding teeth +had points on them not unlike a pig's, and possessed no apparent +resemblance to the wonderful curved and ridged surfaces seen on the +teeth of the modern horse. What his skin and hair were like can only +be conjectured. In the restoration which Mr. Knight has made, at the +suggestion of Professor Osborne, an interesting inference has been +drawn. That he was a creature of the forest is suggested by his +spreading toes, which would keep him from sinking in the soft soil. It +is consequently surmised that he was dappled with spots which allowed +him to rest unnoticed on the sun-flecked floor of the forest. Mane he +had none, and his tail was probably tufted slightly at the end with +hairs, which were increasingly short as they approached the top. He +had no forelock, and the hair along the ridge of his neck was a little +longer than the rest, and stood erect. Browsing about on the soft and +tender herbage of his woodland home, his teeth had as yet no tendency +to become specialized. The molars had mounds upon them, developing, +perhaps, more into the shape of the points of the hog's, but even +still quite generalized teeth. His main enemies, from whom, perhaps, +he could with little difficulty escape, were creatures related to the +hyenas of to-day. Perhaps, like their modern representatives, they +preferred eating their flesh tainted to exerting themselves enough to +capture and kill their prey. By the time we advance a little further +into the Tertiary, though still in its early portion, a remarkable +change has already come about. The fifth toe, which in the earliest +horse hung upon the side of the front foot, has completely +disappeared. The change in the hind foot has gone still further. The +hind leg in many animals evolves more rapidly than the front. The +heavy work of running is always done by the hind feet, while the front +feet serve rather as a prop to keep the animal from falling than as +the actual means of locomotion. Hence the hind feet and the muscles of +the hind quarters are almost always heavier than the front. Possibly +on the front foot the little fifth toe was less of an obstruction, and +persisted after the early horse had lost the corresponding toe on his +hind foot. This process has gone on still further in this second +stage, and the hind foot has but three toes, while the front still +has four. This is not the only advance. Already the middle toe of the +original set of five is becoming emphasized. The weight is thrown more +forcibly upon it, as with the human foot it is upon the inner or big +toe. The middle toe is growing larger and larger, and the nail upon it +is spreading around it and is growing firmer. The creature, too, is +standing more nearly upon his toes; his legs are getting longer; he +stands higher from the ground, and now has come to be the size of a +hound. + +We can only surmise why this creature should have undergone such a +change, but the presence of flesh-eating animals having the size of a +fox, and presumably of the fox's swiftness, probably tells the story. +The little bands of early horses, pursued by their carnivorous foes, +were slowly modified into swifter creatures. It is not so much that +running made them fast, as that the slow ones were continually being +caught. If this process of constant elimination of the slow members of +any herd is kept up long enough, the group will necessarily develop +speed. As time goes on, of these early horses those which happened to +have longer legs and stood higher upon their toes won in the race, and +handed on their qualities to their long-legged descendants. As the +animal rose upon his toes, the inner toe, corresponding to our thumb, +was first raised off the ground and rendered useless, while a similar +change came over the corresponding toe on the hind foot. The hard work +of running being done on the latter, this superfluous toe was more +detrimental there than on the front foot, and disappeared, +consequently, more rapidly. In time, however, it also disappeared from +the front foot. Gradually the further elevation of the foot lifted the +toe, which corresponds to our little finger, off the ground, and this +now disappears also. + +With increasing toughness of the grasses, as the climate becomes drier +and the region more elevated, the teeth of the horse are given harder +work. The points begin to spread into ridges and to unite with each +other in such way as to form the crescents, which are later to be so +characteristic of the teeth of the modern horse. + +By the middle of the Tertiary this ancestral horse has risen in height +until he is taller and heavier than a setter dog. Three toes are found +on each front foot. The middle toe is getting constantly more +developed, though the smaller toes are evidently still of use. The +ridges of the teeth are quite crescentic now on the outer side, and +becoming better adapted to the evidently firmer food which the +creature is obliged to eat. + +As we come toward the end of the Tertiary, the development which had +been all pointing in one direction has advanced very much further. The +creature now would be undoubtedly recognized by anyone as a horse. The +legs are longer and straighter; the middle toe has become the only +useful toe, though on each foot a smaller toe, slender and probably +useless, still hangs on either side. Two similar useless toes to-day +hang at the back of the foot of the cow, which is now walking upon her +two toes, which give her the appearance of carrying a cloven hoof. +That is to say, the first toe on the foot of the cow has disappeared, +the second and fifth hang useless and much diminished at the back of +the foot, while the third and fourth are both well developed and +serviceable in walking. + +The late Tertiary horse has grown to be the size of a burro of to-day, +though probably it was a little more slender. The teeth are quite +horselike, both in shape of the crescentic ridges on their surface, in +the length of the teeth in the jaw bone, and in the fact that the +crinkled edges of enamel on the upper surface are protected on either +side by dentine or by cement. These surfaces, being softer than the +enamel, wore away somewhat more rapidly and allowed the sharp edges of +enamel to stand up in ridges. This plan increases the grinding power +of the teeth. + +With the oncoming of the Era of Man the horse reaches his modern +splendid development. During the early Quaternary the horse was +perhaps in some of his representatives a larger creature than he is +to-day. Each foot now has but a single toe. The nail has spread around +firmly and heavily, until it has become a splendidly developed hoof, +permitting the animal to travel with speed over firm and often stony +ground. The side toes have disappeared completely from the outside of +the horse's leg, although upon removing the skin it is easy to find +the long splints, which are the remnants of toes, which have not yet +quite disappeared. His heel has been lifted in the air until it is +eighteen inches off the ground, and he is standing like an expert +dancer upon the tip of his toe. The body of the horse thus being +lifted far off the ground, a new development becomes necessary. All +through the growth of the creature the neck and head have been obliged +to lengthen correspondingly. Every animal must be able to bring its +head down to the level of its feet in order that it may drink. Various +animals use different methods to accomplish this result. The giraffe, +with his enormously long legs, has a correspondingly long neck, which +lowers his mouth to the ground. Even with this extended neck the +giraffe's legs are so exceedingly long that he is obliged to spread +his front feet when he wishes to reach the ground with his head. The +elephant has pursued exactly the reverse plan. Using his tremendous +head as a battering ram in fighting, and using his enormous tusks both +in battle and in uprooting young trees, a lengthened neck is +absolutely out of the question. Furthermore his front teeth have grown +so prodigiously that they would interfere with his getting his mouth +to water. Accordingly, his nose has lengthened its tip until it +reaches the level of his feet, and this nose becomes to him the main +organ of grasp and of touch. To drink, its end is inserted in the pool +and water is drawn up the nostril. If the animal were to attempt to +draw it all the way back into his throat, it would inevitably strangle +him by getting into his windpipe. Accordingly, when the nose is well +filled with water, the tip of it is inserted in his mouth, and the +water discharged by a quick puff. The horse has taken a method +intermediate between these. It had moderately lengthened both neck and +head in order to get to the ground with its nipping teeth, and thus to +gather the grasses which serve as its principal food. + +The mammalian teeth, while of four kinds, really in most animals serve +but two purposes. The front teeth consist of the incisors and canines, +and are used for biting. The hind teeth, consisting of premolars and +molars, are used for grinding. In the horse, the jaw has lengthened +between these two sets, carrying the biting teeth far forward of the +molars. It is this gap in the row of the horse's teeth which makes it +possible for us to insert the bit into his mouth. + +Now comes a strange accident into the life of our American horse. +Creatures of the same kin had been evolving in Europe and Africa, but +the developments are more distinctly horselike, it would seem, in our +own country. Then for some reason the horse disappeared completely +from American soil. Doubtless two things happened. First of all, some +of them migrated across a stretch of open country which then connected +America with Asia in the neighborhood of Bering Strait. These +creatures spread first over Asia and then over Africa and Europe, +leaving their skeletons scattered over this enormous stretch of +country. Asses and zebras are still found abundantly and widely +scattered, but the wild horse of to-day is seen only in western Asia. +What happened to those who remained in America we shall possibly never +know. Some surmise that a fly not unlike the tsetse-fly of Africa +killed them out. Perhaps the members of the cat family, which are +steadily growing larger and fiercer, fed on their young if not upon +the older ones, and exterminated them. Perhaps the Glacial period +which followed was too cold for them. But, whatever may have been the +cause these horses died out not only in North but also in South +America, to which country they had spread. + +The old world horse was the companion of man. The skeletons of those +found with early man in the caves of Europe look as if the horse had +been a creature to draw man's burdens and to serve him for food, +rather than to bear him upon its back. Its roasted bones are often +found about the old tribal fires. Upon the discovery of the new world +the Spaniards brought with them to Mexico and to the Mississippi +Valley the horses which carried them in their battles against the +Indians. In the course of these frays many riders were killed and +their horses roamed wild. Slowly they made their way to the western +plains; gradually they became tougher and more wiry; their diminished +hoofs learned to catch more carefully in the rocks of their mountain +home; and the mustang and bronco of more recent years are the +descendants of the little dawn horse, whose dainty skeleton is found +in the rocks over which his later descendants, after a long stretch of +perhaps four million years, are now running. + + + + +CHAPTER IX + +EVOLUTIONARY THEORIES SINCE DARWIN + + +In considering the value of Charles Darwin's work and its permanent +effect upon the thought of mankind, we must be careful to distinguish +between two phases of his effort. It was his aim to prove two +propositions: first, that there is such a process as evolution; +second, that he had discovered the method by which evolution is +accomplished. Before his time there was no general agreement as to the +fact of evolution. People generally thought the idea absurd, as well +as irreligious. All previous efforts on the part of advanced thinkers +to persuade mankind of the truth of evolution had been nearly without +effect. Among the early philosophers the whole idea was purely +speculative. They made no attempt to prove it, and the conception was +without influence upon the thinking of the ordinary man. This remains +true until the time of Lamarck. This French genius succeeded in +persuading not a few people of the validity of the idea of evolution. +He probably could have convinced many more had it not been for the +hostility of Cuvier. Accordingly, Charles Darwin's "Origin of +Species" fell upon a world entirely hostile to the idea, when it +thought of it at all. Within fifty years of the publication of this +wonderful book, probably the entire scientific world is agreed that +evolution, in some form or other, is the undoubted solution of the +mystery of creation. The materialist may think of it as a mechanical +process relentlessly working itself out without design or purpose. The +theist will accept it as the plan by which Eternal Power steadily +works. The devout Christian or Jew will see in it God's method of +creation. The idea of development has penetrated every science that +has to do with animals or man. It is even beginning to influence such +inorganic sciences as Physics and Chemistry. We now hear of the +evolution of the elements, and the evolution of forces. The world has +been persuaded that evolution is true, and this is primarily the +result of the work of Charles Darwin. It is astonishing that so great +a revolution should have come in so short a time. + +The other phase of Darwin's work was his attempt to find the agent +which is bringing about the actual transformation of animals and +plants. As we have seen in the preceding chapters, it was his idea +that natural selection was the efficient agent which constantly +eliminated all unfit variations, leaving only the best to carry on the +work of the world and to reproduce their own fit kind. Many +biologists since his time have doubted whether unaided Natural +Selection will account for the constant advance in organisms. This is +the part of the work which is often seriously questioned. + +Weissman and his co-workers have contended that this unaided principle +will serve. Most biologists have asked for some more efficient cause, +and assert that selection does not account for the appearance of +variations, but only for their preservation, and that any valid theory +of evolution must show how variations originate. It is chiefly in this +respect that Darwin's work has failed to satisfy many later +biologists. When we hear a scientist speak of Darwinism as being dead, +this is what he means. He does not think evolution false, but believes +that Natural Selection is not sufficient to account for evolution. +There are three main difficulties involved in Darwin's theory. The +chief defect lies in the fact that selection cannot originate +varieties. In all his earlier works Darwin simply accepted variations +as he found them. He was content to say that all species varied +constantly, and in every direction. He gave no theory to account for +variation. Whenever he took measurements of the dimensions of any +large series of objects of the same kind he found these measurements +to vary, apparently, in all directions. Upon the facts of these +variations, and without accounting for them, he built his own theory +of evolution. He realized his weakness, and acknowledged it in his +book. He probably did not anticipate how insistently later biologists +would demand an explanation that would account for this variation. In +his later work, responding to this criticism, Darwin originated a +theory which he called Pangenesis. He believed that when an adult +animal had responded to his environment and acquired a new character +he could transmit this character to his offspring. At that time no one +doubted this fact. The whole theory of Lamarck was based on the +assumption that this could be done. Darwin suggested that every organ +of the body threw off minute particles, which he called pangenes. +These little bodies, carried by the blood, were taken up by the egg +cells or sperm cells, and the latter cells determined the future +development. Consequently, the character of the new individual was +determined by the parental pangenes. In this way the gain acquired by +one generation could be passed on to the next. This theory was purely +speculative. He never pretended that there was the faintest +corroborating evidence visible to the microscope in the organ, in the +blood, or in the germ cell. It was not an accounting for what is, but +for what it seemed possible to him might be. + +This theory of Pangenesis, in the shape in which Darwin promulgated +it, has dropped out of consideration almost entirely. DeVries of +recent years has revised it, but with distinct modifications, and most +biologists pay no attention to it. + +There is a school of biologists, headed by Weissman, who have come to +be known as Neo-Darwinians. These men have insisted that Natural +Selection, if properly understood and developed, is quite sufficient +to account for the fact of evolution, including the appearance of +variations. Weissman himself is a microscopist of more than common +skill. He is thoroughly accomplished in the most modern methods of +killing, fixing, staining, and mounting. This worker's acquaintance +with the intimate structure of the cell is probably as great as that +of any other man in the world. Weissman asserts that he has seen +inside the nucleus all the machinery necessary to explain how the +father hands over his qualities to his children. He insists, equally +strongly, that this process is such that no father can hand to his +child any qualities which he himself did not have at least in +potentiality at his birth. Everything the individual acquires during +his lifetime is his own possession, which he may use and develop to +the utmost extent, but it dies with him. His children, born after he +possesses it, can no more inherit it than those born before. Weissman +expressed this in his famous statement that "There is no inheritance +of acquired characters." The biological world has had no shock equal +to this since Darwin's time, and there are few other questions to +which scientists to-day return with such constant vigor. + +If what Weissman says is true, that no variation or development which +comes to an animal during his lifetime can be transferred into his own +germ cells and handed on to his children, then it becomes evident that +we must find some cause of variation that acts within the germ cells. +This is the difficulty which Weissman meets. He says that there are +small particles in the nucleus of each cell; that these particles +which he calls determinants decide the form and the course of +development of that cell; that when that cell divides to produce +another cell it gives to this other cell one-half of each determinant. +As a result the second cell grows to be like the first. This tells us +why offspring are like their parents. There is nothing in the theory +thus far to show us why offspring are not exactly like their parents. +In other words, there is no accounting, thus far in the theory, for +variation. When the biologist studies carefully the history of an egg +while it is being formed, he sees that at one stage in its development +it throws away not one-half of each determinant, but one-half of the +determinants. When an egg does this, it deliberately casts aside +one-half of the possibilities of its own development. This throwing +away is quite as effective for all its descendants. Any ancestral +quality now lost is lost from the line forever. In the formation of +the sperm cell set free by the male a similar throwing away of +one-half the characters has taken place. The egg cell and the sperm +cell fuse together. There are as many possibilities now as there were +in either parent, but not all the potentialities of both parents. Half +the possibilities of each have been thrown away, and hence cannot +appear in the offspring. By this constant process we get, in every +generation, new combinations of qualities. This is the main cause, +says Weissman, for variations. + +There is, however, another possible cause. Each cell has enough +determinants in it for many individuals, and it seems to be more or +less a matter of accident which qualities shall come out. It has been +suggested that as an egg lies within the gland, a blood vessel may +bring blood to it in such way that a determinant, lying in a certain +position in the egg, may get the richest supply of blood, and hence +develop at the expense of the less nourished determinant. By these two +methods variation comes into an animal's life, if Weissman and his +school are to be believed. + +This is a serious blow, if true, to many theories of evolution. The +great mass of evolutionists still feel that somehow there is an +influence by which the environment produces variation. How the +influences of the surrounding world can get down into the body of the +parent and affect the egg is unknown. This is freely confessed by +every biologist. All are agreed that Weissman's work has made us +cautious, and prevented our lightly accepting a belief in the +influence of the environment. Yet it is felt by many that slowly and +gradually, in the long run, the germ is affected in the same manner as +is the body of the parent. In other words, even those who are not +followers of Weissman, have accepted the idea that there is little +inheritance of acquired characters. Yet they return to the belief that +somehow, in some way as yet unexplainable, the main cause for +variation in animals lies in the situation in which they live, and +tends toward better adaptation to that situation. + +Whether men with this conviction are merely reactionaries whose +confidence is returning, or bold thinkers whose views will ultimately +prevail, time alone can tell. + +A second strong objection was brought against the theory of Natural +Selection. Darwin declared that small variations in favorable +directions are selected and become the starting point of new and +better things. It is soon seen, however, that the effect of unaided +Natural Selection would be but to mix new departures with the old +forms, and soon swamp out any progressive tendency. Whenever a genius +appeared, instead of finding a corresponding genius with which to +pair, it mated with the average of its own species. Hence its +offspring were nearer the average than it was, and their offspring +still nearer. Thus whatever advantage the genius originally possessed +gradually sank into the common level. + +It was Moritz Wagner, a German naturalist, who first insisted that if +favorable variations were to amount to anything these possessors must +not only mate with others of their same kind, but must also be +prevented from mating with the old average group. Accordingly, the +belief arose that, under ordinary circumstances, variations returned +to the common level. Wherever a varying group became separated by any +barrier from mating with the rest of its species, and had only its own +kind to pair with, a new species sprang up. This barrier might be a +desert, or an impassable mountain range, an arm of the sea, or +anything else that the animal could not, or would not, cross. Isolated +in this way, the little group that had an advantage in a different +direction could develop its tendencies, and a new species would be +made of what had been previously only a geographical race. In this +matter of geographical isolation Wagner is very strongly supported by +the American zoölogist, David Starr Jordan, who believes that no two +closely related species of animals ever occupied the same geographical +area. Both Wagner and Jordan are ardent admirers of Darwin and his +theory of natural selection, but both believe that it is necessary to +add the idea of isolation in order to make natural selection +effective. + +George John Romanes, a British naturalist, has added to Wagner's idea +of isolation, the expanded conception that there may be isolations +that are not geographical. For this phase, Romanes has coined the term +physiological isolation. Something in the structure or habit of the +animals with the new variation prevents them from mating with the +older type. Occasionally it is a difference in the structure of the +reproductive organs themselves. This, however, is not the only +possible divergence. The mating season in one group may come earlier +than that of the other, or may come during the day, while the main +group is in the habit of mating at night. Anything which keeps some +members of a species separate in their mating from the rest, will +result in the course of a longer or shorter time, says Romanes, in the +formation of a new species. + +A third great objection was raised against Darwinism. The theory said +that only useful variations were selected by nature. It was asserted +by objectors that the earliest beginnings of any variation must be +too slight to be useful, or as the term went, to have selective value. + +It has been noticed by a number of naturalists that certain animals +seem to carry the development of a peculiarity altogether too far. It +is seen for instance that in the Irish Elk, which has for some time +been extinct, the horns were so enormous as to be a source of danger +rather than of assistance to their owner. It was said that the +tendency to produce heavy horns had gained, as it were, a sort of +momentum, and that this impulse had carried the development beyond a +safe limit. The Irish Elk became extinct because his horns were too +heavy. During the Mesozoic period the reptiles grew too large. They +seemed to have carried size to a point at which it became a danger +instead of a help. They completely passed out of existence, leaving +behind them only very much smaller reptiles. + +Eimer, of Germany, has based on facts like these his theory of +Orthogenesis. He says that variations in animals are not indefinite +and in every direction, but that they follow along clear and definite +lines. These lines, in the case of the elk and of the Mesozoic +reptiles, developed too far, but ordinarily the effect of such a +tendency is distinctly beneficial to the animal. It particularly +assists in carrying on for a time the variations which have not yet +become useful to the animal. It has always been difficult on Darwinian +principles to understand how the beginnings of the useful variations +could be selected before they were strong enough to be of actual value +to the animal. This tendency to variations in certain directions +instead of at random would account for such early development. This +theory of Orthogenesis has not figured very strongly in the history of +the movement, but it recurs at intervals. + +Both in America and France there is a constant tendency on the part of +zoölogists to return to the Lamarckian idea that it is the use of an +organ that develops it, its disuse that makes it fade away. This is +undoubtedly true of the individual, and although Weissman insists that +it is useless to the species as a whole, many zoölogists are slow to +relinquish entirely the idea that somehow these favorable developments +become reproduced in the offspring. + +Professor Cope, the American paleontologist, was a strong believer in +the effect of activity, both upon the individual and upon his +descendants. He believed that the insistent beating of the foot of an +animal upon the hard soil of the drying Tertiary plateau, had +influenced the production of a firmer nail, which spread around the +entire end of the toe and made the hoof of the ungulate. He believed +that the use of the teeth in grinding produced a stronger and better +molar tooth, and that the offspring shared in this advantage. Since +Weissmann's time, however, every Lamarckian feels it necessary to +suggest some method by which the altered body of the parent can +produce modifications in the germ plasms from which the young are to +spring. One of our later biologists begins to talk of some effect +comparable with wireless telegraphy or induced electricity. He +believes that organs in the adult, not necessarily by direct action, +but by action from a distance, may alter the germ. Of this, there is +no proof at present. Others have suggested that just as the ductless +glands pour into the blood chemical substances which materially affect +the growth and development of other portions of the body, so similar +enzymes, or other chemical substances, may be sent into the blood, +which subsequently bathes the germ cells of the coming generation and +produces the change. But of this, again, there is no proof. We may +believe that acquired characters are transmitted, but we certainly do +not have a very clear idea as to how it can be done. + +One of the strongest objections to Darwin's idea of evolution by +natural selection of small and favorable variations, is that the +process is too inconceivably slow to account for the enormous progress +which has been made. The answer has always been that our observation +ran back so short a time that we really have no clear idea of how +rapid evolution may have been. Again, it has been answered that +transitional geological periods, in which there is much change in the +physical geography of a country, will produce more rapid evolution +than we at present are experiencing. + +Hugo DeVries, of Amsterdam, believes he has found the answer to this +difficulty. Outside of his botanical garden an American species of +Evening Primrose had run wild. In looking over a number of these +plants he found, every here and there, certain peculiar members of the +species. They differed noticeably to the practiced eye from the rest +of the group. When they were planted and crossed with each other, and +the resulting seeds were again planted, the peculiarity remained +constant in all the members of the collection. Here then we have a +true variation, not large in amount, but at the same time quite +definite, and which from the first remains true. Here are the +beginnings, says DeVries, of new species. They are true from the +first; they can live among other members of the species and still come +true; they do not need isolation, at least in Wagner's geographical +sense. These forms DeVries calls mutations. It is his thought that a +species may run along uniformly for a long time when, from some cause +which he has not determined as yet, instability comes into the species +and it varies in quite a number of directions. Each of these +variations may be the starting point of a new species. DeVries +believes that he has at least half a dozen mutants of his new Evening +Primrose. + +This theory of Mutation has been eagerly seized upon by many +botanists. The zoölogists have not accepted it quite so +enthusiastically. If this is the chief method by which species +transform, it seems strange that we do not find more mutations than we +do. Perhaps we do not look carefully enough; perhaps we shall find +them a little later. Just at present it seems premature to believe +that all evolution is by mutation, although quite possibly some of it +is. The main apparent advantage of mutation is that it hastens the +time in which a new species may arise. + +There are certain difficulties which run back into the problem, and +which must first be reasonably solved before a clear understanding of +the idea of evolution is possible. The first of these is as to the +nature of life. What is life? The reply of the biologist will probably +be that so far as its material side is concerned, it must be answered +in terms of physics and chemistry. As to any side not material, if it +have any such side, science says that the chemist can have nothing to +say. The chemist may have an opinion of his own based on some other +ground than his chemistry, but so far as he is a chemist, he has no +opinion. The chemical side of life is being very carefully and very +fully investigated. We are certainly being brought nearer to the +borders of the living substance. We are rapidly gaining fuller +knowledge of the physical and chemical processes which constitute +life, or with which life is always associated. If we gain this +knowledge we shall be in better position to solve many of our other +problems. Even then there is a problem which preceded and which will +possibly always defy solution. How did life originate? Has it +developed out of chemical and physical activities which we know as +heat, light or electricity? If so, what were the conditions under +which it developed? If we understand the nature of life, and the +conditions under which it developed, we may be able to produce it at +will. + +A few scientists may hope dimly that this will be attained. I suspect +a great majority believe it to be impossible, and that the question as +to whether life evolved upon this planet, or this planet became +infected with life through meteoric dust from some other center, will +forever remain an unsolved problem. + + + + +CHAPTER X + +THE FUTURE EVOLUTION OF MAN + + +The disturbance of mind created by the publication of Charles Darwin's +"Origin of Species" would have amounted to nothing if the theory had +been applied to the lower animals alone. Few people would have +disputed that a cow and a buffalo had descended from the same +ancestor, or that monkeys and apes were of a common blood. The whole +theory would have been looked upon by those outside the biological +world as entirely an academic question, in which they had little +concern, and less interest. But within this century the scientist has +so persuaded the world of the unity underlying the activities of the +universe, that so soon as a principle is established men begin to run +it out to the very end. Everyone knows perfectly well that if it could +be proved that the dog and the horse had a common ancestor, still more +if it could be made apparent that the dog and the frog and fish had +sprung from the same stock, then there could be no question of what +would be the final application of the theory. Man himself could be no +exception to the law. So the battle dropped at once upon this most +interesting point, and around this center the contest has waged. + +What is the origin of man? Who are his ancestors? As soon as we ask +the question there is no doubt whatever as to the answer, if we accept +the principle of evolution. Our only means of judging relationship +between animals is by the similarity of their structure. As soon as we +come to examine the other creatures even in the most cursory fashion, +there is only one group which in any close degree resembles the human +species. Our nearest relatives among living animals must undoubtedly +be the apes. Some little distance farther away stand the monkeys, and, +structurally speaking, there is more difference between a monkey and +an ape than there is between an ape and man. The gap between man and +his relatives of this group, known as the primates, is a mental, not a +physical one. While his brain and his mind have developed far beyond +theirs, the rest of his body is comparatively close to that of an ape. + +Probably no one can face the possibility of his being descended from +creatures not unlike the ape, without feeling a stirring sense of +repugnance. The least aristocratic of us hesitates to name in the line +of his ancestry creatures so unlike himself as the members of this +group. It seems to us impossible that we should have descended from +creatures as lowly as they. If evolution is true, these are among our +near ancestors. Back of the group of primates lies a far less +developed set of insectivorous animals, behind them the reptiles, +behind them the fishes. When we get back this far we are less certain +but most probably the worms take up the story. So our ancestry runs +back to the very beginning, when it originated in the one-celled +animals which are also the ancestors of all the rest of the animal +world. If we are inclined to deny our ancestors in the trees, what +shall we say of our forefathers in the seas? + +The question of course is not to be decided by our likes or our +dislikes. If the evolution of man is true it will not make it less +true because the process is not to our liking. It is our part, if this +be the truth, to accept it as we do any other truth. Surely those of +us who are moral of thought are not willing to disbelieve a truth +because it is unpleasant. + +The newness of the idea is the chief reason for our dislike of it. +This lowliness of origin should not be distasteful to us. Nothing +about Abraham Lincoln seems to us more wonderful than that a man who +towered head and shoulders above his generation, indeed above most +generations of men, in his fineness of life, in his nobility of +purpose, in the integrity of his aims, should have been of +exceedingly humble extraction. It only adds to the glory of his later +achievements that he should have lived in a cabin, have spent his +young manhood splitting rails and running a flat-boat, and have gained +his education almost unaided from a few books and much meditation in +front of a log fire. + +That the greatest military General on the Union side of the Civil war +should have been the son of a country tanner, and as a boy, not +over-shrewd in the matter of bargains, adds to the glory of his later +life. The simplicity of his childhood gives new luster to the power +with which he led the forces of a nation to victory, and then went to +a battle no less noble in his long fight for honor while suffering +from disease and approaching death. Why then should we feel that such +beginnings in the lower world are too humble for man? Why do we think +his present superiority diminished by his lowly origin? Why can we not +see that precisely the reverse is true? The more humble the level from +which he sprang the more gloriously creditable is his present +position. Instead of being ashamed of having risen from the brute, it +should be the glory of man that he has so sprung. His chief +superiority lies in the fact that while they have remained where they +are, he has so completely outdistanced them as to have placed a gap +between himself and them that seems almost impassable. Furthermore, +if man with his present glory of intellect and of moral impulse, has +sprung from a creature whose superiority to the ape lay chiefly in its +potentialities, then it does not yet appear what he shall be. We can +judge the future only by the past. Through the long ages the +development has been very slow. Through the last hundred thousand +years the development of man has been wonderfully rapid, compared with +what went before, though it seems slow enough when we look at it from +the standpoint of our historical and traditional reports. But with +this added impulse, this rapid improvement that has come with the +development of mind instead of muscle, of tooth and of claw, we have +every promise of an evolution that shall far surpass anything that has +yet come. To-day our leaders are way beyond the average of the mass. +Who shall doubt that in a not too distant to-morrow, the masses shall +be where the leaders of to-day now are. We shall not then have reached +a dead level of superiority. Our leaders will have moved on as rapidly +as have the masses, and will be as far ahead of them then as they are +now. It shall be their work to apprehend new virtues, and to work them +out in their lives. The masses, seeing the beauty of the lives of the +leaders, recognizing in those lives the revelation of the divine power +which they have apprehended, will hunger to learn of them and to lead +lives like theirs. To this process who shall set an end? The advance +is slow, as in all evolution; but anyone who wishes to do so may +easily detect the direction of the current. + +The evolution of man's physical frame probably has nearly ceased. +Gradually organs that are useless to him are passing away. Slowly his +hands are becoming more delicate and refined and skilled. But his +evolution has begun to work itself out on entirely other lines. We +sometimes hear that the men of the past were the full equivalent of +the men of to-day. Scholars like to tell us that the population of +Athens was finer in quality than any population that has existed +since. We must remember that group after group of men may be expected +to specialize intellectually and fail to develop morally and +physically. Under these conditions this little branch of the human +race runs through its forced flowering and comes to an end. With the +study of history and the earnest investigation of these lives of the +past, new possibilities arise within the human family. The next race +that flowers may take longer to decay because it understands better +the weaknesses that carried away the preceding civilization. In time +there will arise a civilization that understands the past. A whole +people will some time realize that intellectual development alone will +not save it, or Athens would have lasted; that moral development +alone will not suffice, or Judæa had been permanent; that physical +development will not serve, or Sparta would stand to-day. Some day +there will arise a nation that will see to it that every intellectual +advance is accompanied by an equivalent moral and physical advance. +When this time comes we shall have a race which can survive. Are we to +be that race? The sins of man are generally the dregs of his brute +ancestry. Bestiality of life was once common enough to attract no +attention. Kings and nobles were not supposed to be clean so long as +they confined their bestial relations to those below them in rank. +Gradually men are becoming ashamed of uncleanness in life. Some day +there will be no difference so far as purity of life is concerned, +between the two who present themselves at the altar asking the +blessing of God on their union. + +If anyone doubts that English speaking people are becoming cleaner of +life he needs only to consult the literature of the past. No one +dreams of finding fault with Chaucer because his stories related in +the company of men and women often would not bear such telling to-day. +Shakespeare, with all his wonderful genius, needs expurgating if one +would read him aloud comfortably to a mixed audience. And these are +the shining stars. When we drop below them, the literature of their +time becomes nearly impossible to read. Fielding and Smollett and +Stern helped to build up the English novel, but the stories they tell +speak of the grossness of their time in language that is unmistakable. +We are by no means clean to-day. A fair proportion of our novels leave +much to be desired. The stage is the scene of much we could wish to +see cleaner. Above all this grossness there towers a sweetness and +beauty of thought, and an earnestness of purpose, a sincerity of +effort, which makes the present time fuller of moral purpose, fuller +of the desire to be clean and to help others to be clean, than graced +any previous period in the history of either England or America. + +Under the change from country to city life man has suffered. Here too +evolution is necessary. City life tells hard on the second generation +and nearly destroys the third; but we have come to understand the +difficulty and are fast remedying it. It is more than possible that +the next generation will see such changes in the life of the worker in +the great center, as shall effectively stop the physical deterioration +that has come to the city dweller. God grant that modern civilization +has had teaching enough and learned its lesson well enough. God grant +further that we may give over slaughtering our most ambitious and +vigorous young men in battle to settle questions which battle can +never settle. God grant that we have come to a turning of the ways +where the life of men, women and children, no matter how humble their +station, shall stand higher in value than the profits of any +commercial venture. God grant that we will soon be firm enough to +declare that a business which can only live by sacrificing the health +and strength of the workers must be counted an unprofitable business, +and be allowed to cease. God grant finally that the American people +may learn from the past to guard against a like fate in the future; +that here may be the people whose strength, intelligence and +uprightness shall lead the world; not for the sake of exceeding the +world, but with the high mission of setting to the world an example of +what can come to a vigorous, free and God-fearing people. + +In the early history of the evolution of man the struggle almost +always concerns the individual. Gradually the family comes to be the +fuller unit. Only that is success which leads to the success of this +higher group. After a time the family broadens to the tribe, and then +the tribe to the nation. The evolution of social institutions is at +present going on at an enormously rapid rate. Throughout the civilized +world democracy is coming to its own. Even where the form of monarchy +still prevails, the subjects of the monarch are having more and more +rights. The people of England are surely as free as are the people of +the United States. Increasingly all forms of government will secure +for all their subjects, no matter what their station in life, a fair +share of the general prosperity. In this field, human evolution is +perhaps more rapid than in any other. + +Any individual human being is a network of traits and peculiarities. +He has all the ordinary attributes of humanity, but to the whole +complex he gives an individual peculiarity which is totally his own. +Where did he get his qualities? In the earlier times the fairies were +supposed to have blessed him or cursed him in his cradle. A later age +saw in the stars the rulers of man's destiny. He was jovial, or +saturnine, or martial, depending on the planet which was in the +ascendant at the time of his birth. Now we know "it is not in our +stars but in ourselves that we are underlings." Everything a man is +comes to him from within or from without; from nature or from nurture; +from his heredity or from his environment. From our ancestors we get +all the possibilities of our lives. To a certain extent we are slaves +to our heredity, but not by any means to any such extent as to make us +hopeless, unless our heredity is miserably bad. To the great mass of +us come larger potentialities than we ever develop, and such +possibilities of degradation as, fortunately, few of us ever reach. +Within an enormously wide range, man is the architect of his own +fortune. Only such traits develop as find a stimulus in the +environment. Accordingly, a very large proportion of the development a +man may achieve depends upon the circumstances under which he is +placed, or, what is far more to the point, in which he may place +himself. Man is not the blind sport of a relentless destiny. It is his +to choose his environment; it is his to modify his environment when he +cannot leave it. To an extent which no other animal has ever +approached, man is the arbiter of his own destiny. A hypothetical ass +may stand helpless between two equidistant bales of hay, but no human +being is ever so helpless a sport of his environment. As it is, he may +drift or he may rove as he pleases. To one man the current may be +stronger than to another. There may be now and then a child so +feeble-minded as to be unable to decide the course of its own life. It +will not be long before society will see to it that such a life leaves +behind it no strain cursed with its fatal weakness. In this effort to +advance, man has all the advantage that comes from concentrated social +effort. No man may live to himself. To every man in our community who +desires it, a helping hand will be stretched. Often a hand will be +stretched to him and he will be steadied whether he will or not, +until his own will reforms itself and gains the mastery. + +Inasmuch as all that is in man comes from his environment or from his +heredity, the only way in which the race of men can be advanced is by +improving their environment or by bettering their heredity. The first +of these is the province of the sociologist; the second that of the +eugenist. The sociologist has for some time been giving his careful +attention to the improvement of the environment. In every large city, +a man must build for himself a house fit to live in, if he build it at +all. Whether he erects it for himself or for another makes no +difference. Society will no longer allow him to build a home which is +a detriment to the one who lives in it. Not only must he make himself +a decent home but he must keep it in decent condition. The community +will not allow him to endanger his own health, or that of his +neighbor, by an insufficient method of attending to his garbage, or by +a lack of ordinary cleanliness. If he will not clean his premises +himself, the law sees to it that they are cleaned for him. Already we +are beginning to understand that no man has a right to employ another +man or woman or child at wages which are not sufficient to maintain +the one thus employed. The wages of many people are exceedingly +meager, notably those of women and children. He can read but ill the +signs of the times who does not foresee an early end to the exploiting +of the labor of these helpless creatures. Humanity has determined +firmly that these things must pass, that the young child must not +labor long or hard, that a woman must not be taxed beyond her +strength. Already in England there is a partially successful movement +which will doubtless spread to this country to provide that a woman be +granted a little time before and after the birth of her child during +which she shall not be allowed to suffer because her power to earn a +wage is temporarily gone. These things cannot fail in the long run to +strengthen the people. They strengthen chiefly the present generation. +The blight of the fact that acquired characters cannot be transmitted, +meets us here. This improved environment can only slowly, if at all, +improve the race, and every effort made in this direction must be +repeated with each generation. + +Under such circumstances is it to be wondered at that the eugenist is +hoping to raise the strain? Any improvement he can bring about is not +only valuable for the generation in which it comes but is carried on +into the generations which follow. This is the hope that strengthens +and sustains him in his effort. The science of eugenics is so new, so +little is surely known concerning the transmission of human +characters, that no one is able as yet wisely to say what course is +to be pursued in improving the race. But the problem is so interesting +and its outcome so overwhelmingly important that men will never cease +striving to know, and may, before many years, begin wisely to guide us +in our efforts to provide a finer stock. + +Heretofore our efforts at improving the strain have been confined to +cattle, chickens and plants. An almost unalterable repugnance rises as +soon as we speak of improving the human strain. Visions, if not +stories, start up at once, of experimental matings of human beings, +and of all other unspeakable abominations which no decent man expects +to happen or even wishes to attempt. If there is one thing in human +society the value of which has been demonstrated through the unending +ages, it is the monogamic marriage. All ideal workers must point to +the life-long union of a strong, vigorous, clean-minded and +clean-lived man with a similarly fine, strong, clean-minded and +clean-lived woman. Such an ideal may be slow in its attainment, but he +aims too low who aims to secure anything less than this. The long +struggle out of bestiality into pure monogamy has been so slow, so +gradual, so noble in its attainments, and is still so far from +perfection, that it would be an inconceivably stupid blunder to let go +a single point that has been gained. Whether divorce shall be allowed +to remedy a mistake may be a matter of dispute, but at best it is a +bad remedy for a mistake that should never have been made. No ideal +society could ever consider divorce as any permanent portion of its +activities. Children are not like cattle. It is not simply a question +of their being brought into the world sound and strong. Their long +infancy which in the biological as well as in the legal sense, lasts +until they are grown up, should be spent in surroundings which can +minister, by example and precept, to moral and intellectual +development. Surely no such end can possibly be attained when man and +woman mate lightly, to part quickly. + +At first sight it would seem a wise thing to require health +certificates for those who would be married. I doubt not the Chicago +Bishop who declined to marry his parishioners except under such +conditions, will exert a beneficial effect upon the country by the +attention he thus attracts to the subject. It would be a bad day for +the city if all the clergy and all the other authorities who are +authorized to solemnize marriage should take this step. We have not +yet arrived at such a stage of development that a marriage certificate +is essential to mating, and a restriction of this sort would simply +mean that there could be no legitimate union except of those in strong +health. To the burden of ill health would be added the still worse +handicap of an illegitimate parentage, with all its bitter train of +scorn and shame. Accordingly, it must be possible before the law for +those who are not thoroughly vigorous to marry. But, year by year, we +may come nearer accomplishing a finer mating by the aims and purposes +we foster in the growing generation. Marriages will never be worth +while when they are not freely entered into by the contracting +parties. Choice must be free and unrestricted if it is to last for +life; but this does not mean that it must be unguarded. It would be +bitter folly for parents to leave to their children, without attempt +to influence or restrain, the making of their marriages. The mating of +our children must be inspired, not directed. + +There is one taint from which society has the right and the duty of +freeing itself, so far as in its power lies. This is the taint of +feeble-mindedness. Of all the calamities that can befall a human +being, feeble-mindedness is, perhaps, the worst. From most misfortunes +it is possible to recover; with most of the rest one may exist without +detriment to the race. To be feeble-minded simply means to hark back +to the level of our animal ancestors, without regaining their power to +guide life. The animal is provided with a bundle of instincts which +tell him what to do in all the ordinary emergencies of life. The +human species, in its development, has lost a large portion of its +instincts, and has gained, instead, the power of intelligent choice +and the ability to learn by imitation. When these drop away, man +without his instincts or his intelligence is more helpless than the +brute. Students of sociology are making clear to us that a large +portion of the criminality of the world, much of the looseness of +life, and a large part of the alcoholic excesses are due to this taint +of feeble-mindedness. Recent investigations have made it clear that +one feeble-minded family in a community may, in the course of years, +poison the life of an entire state. The Jukes family in New York, the +Kallikak family in New Jersey, have shown the awful possibilities of +descent from a single feeble-minded ancestor. Prisons, almshouses, and +houses of shame owe their population in no small degree to this bitter +curse. It will not be long before society will learn to protect itself +against such poisoning of the human stock. Nothing is more clear to +the investigator of this subject than that the one overwhelming cause +for feeble-mindedness is feeble-mindedness in the parentage. + +There is one type of mental weakling, known as the Mongolian idiot, +which may arise right out of the heart of an apparently sound family. +But the number of these is comparatively small. The number of +feeble-minded, who are feeble-minded because of their heredity, is +dishearteningly and astonishingly large. Every attempt to examine +large numbers of school children shows a sickening proportion of those +who are distinctly feeble. Every little community seems to have its +boy or girl who is what is known as silly. Such people rarely live +long lives without leaving behind them feeble-minded children, no +small proportion of whom are likely to be illegitimate. Against this +fouling of the stream at its source, society must protect itself. +Legislators revolt at the somewhat inhuman but certainly safe method +of surgically preventing the possibility of the feeble-minded becoming +parents. It would be more creditable and just as effective if society +would take upon itself the tremendously expensive task of caring for +all its feeble-minded in institutions during their entire life. The +cost would be large for a generation, but would rapidly diminish and +eventually become small. It certainly would be the humane way. These +people in good institutions are by no means unhappy. Within the limit +of their capacities they can do many things. Wise management usually +will secure from them labor enough of wholesome and simple kind nearly +to pay for their own support. Nothing could be better for them than to +till the soil, care for the cattle, tend the chickens, and, in this +way, provide very largely the materials on which they are fed. How +this problem shall work out, time only can decide. With it once worked +out, there is no doubt that the level of humanity will be distinctly +raised. No other one feature in the program of eugenics seems more +absolutely hopeful than this. + +In several of the states of the Union it has recently become the +practice to remove the possibilities of parenthood from certain +classes of criminals. The purpose of this is clear and benevolent. +Society has a right to prevent the oncoming of new generations of +foreordained criminals. Underlying the practice is the theory that the +children of criminals are born criminals. It is far from likely that +this is the case. Criminality may be due to a wide range of causes. If +the criminal is one of those actual born degenerates whose whole +mental and physical make-up is so defective that nothing but +criminality can be expected of him, then we have a case in which it is +clear that society may, and should, remove the possibility of having +more generations of the same kind. Probably only a moderate proportion +of the criminals in our jails and penitentiaries belong to this class. +Doubtless a distinct majority are criminals more through environment +than through heredity. Born of average ability, or more, these people +have been criminals simply because they were reared among criminals, +because their surroundings were such as to lead them away from habits +of industry, while they must live. These people were not bolstered by +society, or the church, into a life of self-respect and self-help. +Under these circumstances they fell into evil ways. There is nothing +defective in their mental or physical make-up, that need appear in +their children. If these children are removed from contact with the +criminal class they stand every chance of being as vigorous, as +intelligent, as upright as the average of the community. + +At the recent Eugenics Congress in London one of the speakers +expressed a preference for the son of a husky burglar over the son of +a tuberculous bishop. This is doubtless quite correct, but why should +the bishop be tuberculous? The truth of the matter is, the reverse is +more likely to be the case. Personally, I should prefer to be the +offspring of a husky bishop. In dealing with criminals, then, with a +view to cutting off their posterity, we must be careful to understand +whether we are dealing with a hereditary or an acquired criminality. +If there is a genuine hereditary criminal taint, society is right in +freeing itself of it. If it is acquired criminality, then it is not +transmissible, and the offspring, if placed in a good environment, are +likely to be good citizens. All of which means that, until we are +clearly sure of what constitutes a hereditary criminal trait, we +should move very slowly in the matter of mutilating criminals. + +What steps may the eugenist, with his present limited knowledge, +clearly, hopefully and confidently take to improve the future of the +human species? There is one avenue open to us in this matter in which +we can hardly go wrong. Even our mistakes can work little harm, and +every well-done piece of work in this field will be a blessing to the +race. This step lies in inculcating in our boys and girls high ideals +of parenthood. This is more effective than legal prohibition of +certain forms of marriage which cannot prevent matings, and adds the +curse of illegitimacy to the other handicaps of the children of such +unions. The first step in this process has already been reasonably +well accomplished. Both our boys and our girls are in love with +health. A good husband and a good wife should be healthy and vigorous. +This does not mean that we expect a boy or girl who is looking forward +to marriage to sit down and ask himself deliberately about the health +of the person with whom he would mate. We must fill our children with +the love of outdoor life, with the love of exercise. This will foster +in them an admiration for people who are vigorous of body and alert of +mind. It ought to become practically impossible for a hearty and +vigorous boy to fall in love with a helpless and anæmic girl. It +should be equally impossible for a hale and active girl to admire a +man who was her inferior in either vigor or alertness. The modern +taste for outdoor life has largely brought this to pass among such of +our people as have leisure enough to indulge in vigorous sport. Among +the crowded dwellers in the closer sections of the city such life has +been so nearly impossible that no ideal of vigorous manhood or of +radiant womanhood has had a chance to grow up. With the oncoming of +the parks and play-grounds, all of this, we may hope, will change. +Health and vigor will be no less attainable and hence no less adorable +in the city than in the country. Rich and poor alike will be attracted +by rosy cheeks and an elastic gait. + +Our aim, however, should not cease with a vigorous body. We must teach +our young men and young women the glory of a well disciplined mind. +This should seem quite as admirable to them as a vigorous body. To +them, straight thought ought to be as lovable as a firm and supple +body. In this matter our young people are less exacting. The ordinary +conversation of people gathered together for social purposes is not +particularly intellectual, and any attempt to make it so at present +seems priggish. With a broader education, will come keener demand for +intelligence. We may hope the time is not too far distant when a +question of governmental policy, a new book or play, or a new +discovery in science will stimulate as much conversational zest as now +seems to be gotten from a pack of cards. + +A third feature of the ideals which should be instilled into the minds +of our children is the moral phase. There seems little doubt that this +is on the way. We must not mistake an evident laxness of religious +observance as being synonomous with moral looseness. The revelations +which our recent periodicals have brought us concerning the habits of +business men, of politicians, and of society, have left on many minds +the impression that this is distinctly an age of decadence. Exactly +the reverse is the truth. This is the age of intense sensitiveness to +wrong. In almost no particular is it worse than any previous age in +the history of our country. We openly discuss things which we left +untouched a little while ago. We insistently demand that business +practices to which nobody particularly objected a dozen years ago must +now certainly cease. All of this has produced an erroneous impression +that the times are out of joint. But the dust and dirt in the air is +the unavoidable accompaniment of house cleaning. When doubtful +practices simply have publicity many are awakened to the sense of +their duty to society. Persons who, of themselves, might be willing to +live low and godless lives, dare not do so in the face of society when +our social ideals are finer. I believe there is the utmost hope that +within two generations our young men and young women will scorn +meannesses which we are accepting with entire complacency. + +A close acquaintance with thousands of young men and young women +running through an experience of twenty-five years has taught me to +believe that our young people of to-day are altogether cleaner of +mind, of tongue, and of life than were their parents. There is freer, +franker discussion of many things that their parents would scarcely +have dared mention, yet I feel sure the moral tone is distinctly +higher. I look with entire hopefulness to an early season when the +young man who asks a woman to share her life with him will be met with +the entirely proper question, "Have you kept your life clean for this +event?" I believe that unless the answer can be in the affirmative the +young woman will not be able to have admiration enough for the young +man to cover uncleanness in his life. + +There is one temporary phase of present life which seems discouraging. +The increase in the cost of living, and still more rapid increase in +the standard of living is shifting too late in life the age at which +our young people marry. The result is that one of two things is likely +to happen; either a large number of people are likely not to marry at +all, or the romantic time of life is passed before the event occurs +which it is intended to bless. A young man and young woman who are in +this time of life can deny themselves for each other, can struggle and +plan together, can hope and trust together to an extent that can never +be the case if marriage is delayed beyond the romantic years. + +The best foundation possible for a life of happiness is vigor, ability +and good character. For the lack of none of these can wealth properly +atone. + +There is an apparent tendency to waken to the situation. I hope it +will come soon enough for our young men and young women to get past a +desire for such establishments in life as their parents already have. +With this difficulty removed, with our widespread education, with the +constant diffusion of both information and ideals from our periodical +press I have every hope that the evolution of a new, a finer, and more +vigorous race, will come with a rapidity which nothing that the past +has done would lead us to expect. + + + + +CHAPTER XI + +SCIENCE AND THE BOOK + + +We of the twentieth century have an overwhelming desire to be up to +the times. Nothing but the latest news on any subject will completely +satisfy. We are more anxious for late information than for accurate +information. We have an almost unconquerable feeling that if it is +late it must be accurate. All of us are sensitive to being thought +behind the times. We feel that no stigma can be more invidious in the +intellectual world than the stigma of being out of date. This pervades +the masses quite as strongly as it does the more cultured classes. +Under these conditions everybody wants to know the latest theory that +science has to offer concerning anything that can be brought within +the range of their interests. As a result everybody would like to know +about evolution, were it not for the fact that a great mass of people +have been brought to believe that there is something inherently +irreligious in the idea. Our people have a saving sense of the value +of religion. Denominational control may set lightly upon them. +Certain long revered doctrines may have little practical influence +upon them. Yet inherently they all believe in religion, and most of +them believe themselves to be religious, as indeed they really are. + +It is a most wholesome tendency which leads us to esteem religion as +the main interest in life. We must feel a sense of shame when we +consciously permit the influences, which most favorably mold our +character, to weaken their hold upon our lives. Certainly in our time +religion is the essential agent by which character is molded. Any of +us would be foolishly short-sighted were he willing to weaken the hold +of religion upon his life for the sake of a scientific theory, the +truth or falsity of which could have but little practical bearing upon +his conduct. We must hold to religion at all hazards. We may, when +circumstances so suggest, change our denominational allegiance. We may +and often do interpret our faith quite at variance with the +ecclesiastical body with which we are connected. We may constantly +modify and develop our beliefs. But it is a pitiful life which has +lost the staying and strengthening influence of religion. I believe +this conviction is deep-rooted in the minds of our people and that it +deserves the place it holds. + +To a mind thus essentially religious the announcements of science +often come as a shock. They seem to run counter to our deepest +convictions. It seems impossible to us that both can be true. +Sometimes the more we debate the questions the more contradictory they +seem to become. Every good mind needs unity in itself. No clear +thinker can be quite content when two distinct departments of thought +are at sharp variance in his mind. He may pursue one of two courses. +He may hold to one view with conviction and earnestness and look upon +the other as essentially false. To many religious people all science +that runs counter to their convictions is necessarily false. They +label it pseudo-science and pass it by. If the word pseudo-science is +unknown to them, they stigmatize it as rationalistic, or still worse +as materialistic and let it go at that. + +The other course is to have faith both in religion and in science. + +Such a fair-minded man must ask himself, what is the truth in the +matter? If the scientific fact is true it is to be believed. It may +run counter to what we have believed before. It may seem at first +entirely incredible. But when once he becomes convinced of its truth +the clear thinker must not only accept it, but must accept all +legitimate deductions from it. If it seems true to us we must believe +it. Absolute demonstrable truth, except in the simplest of matters is +almost unattainable. The best we can ordinarily get is a close +approach to certainty, and with this we must be content. In many +matters, indeed in most matters, we must trust the judgment of others +who are better trained in a particular line of thought. + +As to the truth of geology we are certainly wise to accept for the +present the facts and principles commonly accepted by competent +geologists. In biology, we should respect the concurrent opinion of +important biologists. We must not assume that a few biologists who +think as we do are right against the biological world, or that a few +geologists who think as we do are right against the geological world. +For theology, we had better go to the educated theologian. But when it +comes to reconciling two of these and to catching the inherent +correspondence between them, it is often likely that each of these +groups of men is unable to see clearly the view-point of the other. +Here lies our freedom. Here we must either think for ourselves or +think with those wiser than ourselves whose opinions seem to us to +ring true and to focus for us our wavering and uncertain thought. + +Among students of animals and plants there is no longer any question +as to the truth of evolution. That the animals of the present are the +altered animals of the past, that the plants of to-day are the +modified plants of yesterday, that civilized man of to-day is the +savage of yesterday and the tree-dweller of the day before, is no +longer debatable to the great mass of biologists. To older men +hampered by the convictions of an earlier age this dictum of modern +science may still be a little uncertain. + +The working biologists of the world have no doubt. They differ +radically as to what brought about this change, they dispute +vigorously as to the rate of change, but as to the fact of the change +there is no difference of opinion. Under these conditions the thinking +man is out of joint with the times when he sets himself against the +idea of evolution. He may be so immersed in other lines as to be +indifferent to the problem; but when he is hostile to it, he marks +himself as clearly against his day. Many have been against their day +and have been right. Very great men have often been against the +opinions of their times and have come to be leaders of the world's +later thought. But ordinary men in ordinary times who think +differently on a special subject from the specialists of the times are +not very likely to be right. It is safe for most of us to accept as +true an opinion on which specialists on that subject agree. It seems +clear to me then that the thinking man to-day has in the matter of +evolution a double duty. He must become reasonably acquainted with the +theory that so largely affects all present knowledge, and he must +wrestle with the theory until it no longer hinders the hold of +religion upon his life. He may be perfectly sure that he does not +clearly understand both, but he must get them into reasonable +concordance before he can be quite at peace. + +Truth is true no matter how it is acquired. There can be no doubt as +to the essential truth of religion: its fruits proclaim its worth. +There can be no doubt as to the essential truth of evolution; the +clarity it has brought into the sciences is the evidence of the value +of the conception. That it will persist in its present form, that it +will be unchanged by later additions to our knowledge is of course +unthinkable. It may be incomplete, it may be undeveloped, but so far +as it goes it contains the truth. Under these conditions, how can we +bring peace into our own mind? These two important provinces seem so +often to be at variance. The difficulty may lie in one of two places. +In the first place, each truth may be stated in terms so peculiar to +its own subject as to convey no meaning to the student of the other +branch. There is a second, and more harassing possibility. The same +words may be used by students in each branch but each side may put a +different significance into the terms. Then each believes he +understands the other, when he really does not. + +Our theology is man's interpretation of God's revelations of Himself +as recorded in the Bible. Our science is man's interpretation of God's +revelation of Himself in nature. Each is God's revelation, and so far +as we have understood it, that revelation is of the utmost importance +in our lives. Each has all the inherent short-comings of man's +interpretation. Each has all the difficulties necessarily found in any +stage of a developing understanding. We may be sure if we could +thoroughly understand God's revelation of Himself as recorded in the +Bible and his revelation of Himself as recorded in the rocks and the +tissues of animals as well as in the body and mind of man to-day, +there would be no difficulty. When we understand both completely, as +perhaps we never shall, there will be no contradictions of any kind +between them. Even now if we are firmly convinced that truth must be +in both, there will be little difficulty in reaching a workable unity +which will satisfy the present needs of the human mind and will not be +so crystallized as to prevent a future growth. If, however, we hope to +find a unity between a belief in evolution and a belief in the +inspiration and value of the Bible, we must accept both of these in +the terms of to-day. To reconcile a twentieth century statement of +science with an eighteenth century statement of theology would be as +absurd as it would be to reconcile a statement of twentieth century +theology with eighteenth century science. Each century must restate +its truths in terms of its own time. The truths may be at bottom the +same through many centuries but to be clearly intelligible in any +century they must be couched in the terminology of the age. + +It seems to me if we are to understand, in conformity with the thought +of the age, any particular book in the Bible, there are three steps +through which we must pass. We must first ask ourselves the kind of +people to whom the book was originally written. We must know their +habits of life and of thought. Until this is clear in our minds the +book can have little significance. Having built up as nearly as may be +the life and thought of the time, we must next decide what is the +inherent truth taught to the people of that time by the book under +consideration. Much that is written must be simply the setting in +which alone that truth could reach them. This extraneous detail gives +vigor and color to the message but is not the message itself. The last +step and the hardest one to take, the one that to some minds seems +almost irreverent, is to decide the form that message must take to-day +to convey to our minds the same truth which the original message +conveyed to the people of its time. In so far as we succeed in taking +these three steps, we shall get the true message which this book +holds for us to-day. + +When Paul in his first burning letter told the Corinthian congregation +that their women should be silent in their churches, he is not, it +seems to me, giving a message which in those terms applies to the +world to-day. If a woman has anything that is worth saying she has a +perfect right to say it in church. In any denomination in which +religious observance is not ecclesiastically formal she will be +allowed that privilege. By an interesting peculiarity of mind on our +part she may be permitted to do so upon Wednesday evenings, when our +early prejudice still prevents her speaking on Sunday. What is the +truth of the teaching of Paul in this matter? The Christians of +Corinthian times had already begun to suffer from persecution. They +were already despised and distrusted. Men had come to speak ill of +them. Paul's injunction concerning the silence of women in churches +was simply an injunction against their doing those things which in the +thought and habit of those times were associated generally with +looseness of character. Fine Corinthian women did not speak in public. +A woman who would consent to speak before a group of men of Corinth of +that day would by that fact have proclaimed herself a woman of loose +morals. Paul's injunction is that, in this desperate struggle +Christian women should do nothing which could possibly bring them into +disrepute. The lives of Christians must be above suspicion. This +message is certainly as true to-day as it was in the time of Paul and +Corinth. Whether or not a woman speaks in church to-day has no bearing +whatever upon the question. The question is how she speaks and what +she says. If her life gives force to her message and her message +contains God's truth she is entirely free to speak. + +In similar fashion we have changed most beautifully the message which +we have come to love, as the Mizpah message: "The Lord watch between +thee and me while we are absent one from the other." We have +absolutely transformed and glorified the message. It was once the +calling down of the wrath of Jehovah upon one or other of two herdsmen +if either of them should fail to comply with the agreement to remain +within his own boundary. These men whose herdsmen were constantly +stealing each other's cattle agreed to separate because they could not +live in unity. They set up a heap of unhewn stone, and called upon God +to guard and to see that neither of them passed beyond the boundary of +the other. What was once a threat between warring herdsmen has become +a binding link between Christian brothers. No longer do we call upon +the Lord to guard in our absence lest our enemy encroach upon our +domain. Now we call upon him to bind our hearts together so that +neither time nor circumstance can bring division between us. The +menace of a herdsman's wrath has become one of the tenderest messages +of Christian love. + +In the light of the principles stated above, what is the essential +truth that lies back of the earliest chapters of Genesis? First, that +there is one God. Slowly it had been borne in upon the Hebrew mind as +upon no other tribe in the world that the Lord God is one God. Nearly +all the world besides believed in many gods. Each nation had a God +peculiarly its own, each city had a minor god caring for it +particularly. There were gods of the woods, gods of the oceans, gods +of the streams. Gods and goddesses were everywhere. To this people +wandering through the terrible monotony of the sandy desert, the +"Garden of Allah," there came the inspired comprehension of the +eternal oneness of Almighty God. First, he was to most of them the God +of the Hebrew, stronger than the gods of the nations. After a while +under the teaching of prophet after prophet there finally came to the +entire nation the exalted conception that God is one and there is no +other God. This is one of the imperishable revelations of all time. +Beside this, all suggestions of fifth or sixth day, of hours or of +ages are absolutely insignificant. These are but the clothing of the +idea which makes it acceptable to its time. This clothing must change +with every age if it would reach thoroughly the minds of the age. +Underneath and forever lies the glorious truth that the Lord God is +one God. + +The second truth which seems to me to underlie this magnificent +parable of creation is the truth that this great God has created the +universe and that he cares for his people. Gods before had been +objects of terror. Gods before had lived lives such as the people +themselves would not have respected among their companions. Gods +before were to be shunned. If one could but escape the attention of +the gods it was his greatest good fortune. Now we have the conception +of an all-knowing, ever-present God to whom his people are dear. The +terms in which it was stated in those days matter but little. To +modern psychologists even the idea that people are dear to God seems +speaking too humanly. Yet the truth involved must come in terms that +the people of to-day understand. We can best comprehend God if we +think of Him as loving and chastening, even though down in our hearts +we know that these terms are not high enough, are too human to apply +to an Eternal God. But we know no better and they tell us the truth +even though the terms may in time pass completely away. + +Last of all and perhaps most characteristic of the Hebrew people is +the great lesson that this Eternal God, who created the universe and +cares for his people, demands righteousness of his people. To the +nations round about religion was not a matter of righteousness. For +them religion had nothing to do with morality. Thieves might have gods +favorable to them quite as well as righteous men. The worship of Diana +of the Ephesians or of Astarte in the groves of the Asia Minor coast +could be so unspeakably licentious and vile as not to admit of +description to-day. Yet this was all religion. To the Hebrew came the +inspired, exalted conception of a God who demanded righteousness of +his people. Beside this wonderful revelation to the human mind details +of serpents, and of apples, of names of men and of women, of gardens +and of swords are absolutely but the transitory clothing. This brought +them to the minds of the times. The value of the form is evidenced by +the fact that it brought the conception. But we must not lose the +glory of the conception in an over regard for the clothing in which +the idea came. + +Does this mean that Genesis has served its purpose and is to-day to be +conceived of as a beautiful relic of the past, to be reverently +enshrined but not seriously accepted? Far from it. The glory of the +Genesis story lies in its wonderful power to grow. It strengthened +the minds of a persecuted tribe wandering in the desert who finally +settled in a small and barren country. It brought the truth to them so +clearly that they have persuaded much of the world of that truth and +bid fair to persuade the rest. The story has grown with the mind of +man. As it served the Hebrew in his time it has grown to serve others +to this day. Each generation has read the story in the light of its +own times and each generation will continue to read the story in the +light of its advancing knowledge. The only part of the story that can +be affected is the clothing, the inherent truth remains forever. +Furthermore, the story which persuaded the childhood of race is the +story which will persuade the childhood of to-day. In no other form +could the great truth of the Bible be brought to our children as well +as in the form of these early chapters. In early life our children +will accept these stories as literally as the ancient Hebrew accepted +them. As they grow in knowledge, unconsciously and without jar, if we +do not jar them, our children will read into the story what God has +taught them in the world outside. The shock which came to their elders +need never come to them. It is our fault if our children are disturbed +by the conflict between religion and science which disturbed us. There +is no difference between God's revelation of Himself, as we have it in +the Bible, and God's revelation of Himself in nature. The better we +know the Bible and the better we know nature the clearer this will be +to us. + +Perhaps the most severe shock that has come to the mind of religious +man from the teachings of science has been the at first almost +unsupportable idea that man is the descendant of creatures of which +the ape is to-day the nearest representative. He had learned from +Genesis the altogether adorable conception that he was made in the +image of his Maker. It lifted him; it strengthened him; it gave him +more power to struggle. He might know that he had marred that likeness +by wrong-doing, he might understand that the fullness of the glory of +God's image could not shine through his own face. Yet he believed that +he was, in spite of all his imperfections, made in the image of his +Maker. Now comes this horrible linkage with a miserable brute to +either shock and confound him or to degrade him. We can easily +imagine, some of us have bitterly experienced, the shock of this +changed conception. But it was only because we mistook the clothing +for the truth in both cases. We read science in its own terms; we read +Genesis in its own terms. They did not use the same language and they +jarred us to the very soul. Slowly, however, we are coming out of the +darkness of that battle; slowly the glorious light of the beautiful +truth is breaking into our minds and our hearts. + +Michael Angelo painted a wonderful picture of "The Judgment." Here, +seated upon a throne, which after all is only a magnificent chair, +sits a venerable figure of what is really but a nobly-proportioned +man, to whom the nations come for their final reward. He separates the +righteous from those who must forever be sundered from their God. Seen +through the distant past it still remains a majestic picture; but no +painter would think of repeating its conception to-day. + +Quite in the modern spirit is the beautiful lunette which John Sargent +placed in the Boston Library, above his well known frieze of "The +Prophets." It represents "Jehovah confounding the gods of the +nations." The naked figure of suppliant Israel stands before an altar +of unhewn stones, on which burns the sacrifice. The smoke ascends to +Heaven. On one side stands the mighty figure of Assyria with uplifted +mace ready to strike its awful blow upon the shoulders of helpless +Israel. On the other side the lithe, subtle form of Egypt, clasping +the knout, watches its chance to bring its treacherous thong upon the +helpless shoulders of suffering Israel. But Jehovah may not appear, +man may not look on God and live. Jehovah is seen as a glory behind +the cloud of smoke shrouded by winged cherubim. From one side of the +cloud comes a mighty hand meeting with power the force of Assyria. +From the other side, a lithe and sinewy hand thwarts the subtlety of +Egypt. But Jehovah is behind the cloud. + +Again we understand that we are made in the image of our Maker. Again +we understand the power of the uplift of this idea. From the conflict +it has emerged in new and glorified form. Hath a God eyes that he may +see? Hath a God ears that he may hear? Hath a God hands that he may +work? These we know to be but human forms of speaking. Eyes, ears, and +hands we may owe to the brute from whom we have sprung; in our eyes +and ears and hands we show the relationship we bear to them. These are +not the image of God. God is a deeper, a finer, a nobler something +than hands, than ears and eyes. The image of God lies within +ourselves: the image of God is that which makes us what we are. In +every noble purpose, in every earnest endeavor to uplift ourselves or +our fellowman, in every thought that turns us from the evil of a +repented past, in every desire with which our hearts yearn to +strengthen, support and sustain our friends and even our enemies, +shines forth the image of Almighty God. This it is that links us with +the Eternal: this it is that makes it worth while that we should be +Eternal. Besides this what are hands and ears and eyes? We are made, +all in us that is noblest and highest, in the image of our Maker. + +A word in closing. The time is ripe for a broader conception of +theology and of science on the part of those who are not trained to be +specialists in either. We are becoming more and more inherently +religious. We are becoming more and more enamored of the truth in all +its forms. The times are ripe for us to cease the struggle and to +strive for peace. So long as men insist that the important things in +faith are the things on which men differ there will be eternal strife. +So soon as men endeavor to find the common ground between them and +each tries to state his belief in forms acceptable to himself but +involving no hostility to his neighbor, we shall be working for peace. + +Some of our finest men of to-day are being trained in modern science +and in modern theology. There is no scorn in their minds for early +science or for early theology. Each served its age, and each taught +its truth. But its truth must be restated in terms of to-day. The old +creeds will always be loved. The old creeds will always hold our +reverence and allegiance. But each age must be at liberty to interpret +these creeds in the terms in which that age best understands truth. +Each age must be at liberty "to restate the doctrines of the past in +accordance with the newness of the age and with the ancient verity of +truth." How feeble my own attempt is in this matter, I quite +understand; I am still a child of the struggle. It has all come in my +lifetime and I have seen and felt not a little of the bitterness of +it. I believe the time is ripe for a definite peace. I believe our +children, if we do not hamper them, will never know the struggle we +have had. In every great institution throughout this broad land men of +earnest mind and noble soul are teaching the truth as God gives it to +them to know the truth. Let us not hesitate to entrust our children to +their hands. To us they may seem to be teachers of discord but they +are not speaking in terms that we understand. They are using the +language of a new age. Underneath their teaching lies the everlasting +truth. Out of their teaching will come everlasting life. Let us trust +God in the world. Let us believe that in this age he is teaching men's +lips and dwelling in men's hearts. Only so can we give to our children +the best their times can give them. If we insist in holding these men +back to our conception we but deny them the privilege of moving with +God's great procession. We make them laggards when they should be in +the front ranks, their faces lighted by a nearer and clearer vision of +Almighty truth. + + + + +INDEX + + A + + Acquired characters not inherited, 52. + + Adaptation and purpose, 89. + + Adaptation for the individual, 87. + + Adaptation for the species, 125. + + Advanced teaching, 291. + + Agassiz and evolution, 19. + + Age of the earth, 156. + + Allantois of chick, 206. + + American Museum of Natural History, 221. + + Anaxagoras and evolution, 9. + + Anaximander and evolution, 8. + + Ancestry of man, 186. + + Andes rising out of Pacific, 32. + + Aquinas, Thomas, and evolution, 12. + + Archæopteryx, 181. + + Aristotle and evolution, 9. + + Armadillo and glyptodon, 29. + + Artificial flavors, 161. + + Artificial proteids, 161. + + Artificial sugars, 161. + + Ascent of man, 189. + + Asexual reproduction, 194. + + Augustine, Saint, and evolution, 11. + + Australian mammals, 186. + + + B + + Bank swallow's nest, 146. + + Barnacles studies by Darwin, 34. + + Beagle and Darwin's voyage, 25. + + Beauty of human female, 127. + + Biologists accept evolution, 278. + + Bird colors, 131. + + Bird from reptile, 122. + + Bird nests, 145. + + Birds of a region definite, 61. + + Bird song, 135. + + Blowing viper, 107. + + Blue birds and frost, 61. + + Bradbury, Dean, 43. + + Buffon and evolution, 15. + + Bumble bees, 125. + + Butterfly colors, 129. + + Butterfly's mouth, 95. + + + C + + Carboniferous age, 174. + + Carnivorous teeth, 124. + + Caterpillars on leaves, 110. + + Cave man, 188. + + Cells live in water, 166. + + Cenozoic age, 185. + + Cicada killer, 143. + + Circular nest of bird, 147. + + City life in man, 256. + + Clothing of birds, 101. + + Coal plants, 174. + + Cold-blooded animals, 99. + + Color, concealing, Thayer, 115. + + Concealing appearance, 105. + + Cope and Lamarckianism, 244. + + Cope on taste of toad, 118. + + Coral reef formation, 32. + + Country life in man, 256. + + Cretaceous period, 180. + + Cricket song, 134. + + Crinoids, 171. + + Crossing and variation, 53. + + Cuvier criticises Lamarck, 19. + + + D + + Darwin, Charles, + along La Plata, 28. + at Buenos Ayres, 28. + at Keeling Atoll, 31. + at Galapagos, 30. + father of evolution, 21. + in Brazil, 27. + in Patagonia, 29. + in Peru, 30. + on Beagle, 26. + persuaded world of evolution, 21. + studies Lyell's Geology, 26. + studies Malthus, 35. + + Darwin, Erasmus, and evolution, 16. + + Darwin's ancestry, 22. + birth, 23. + burial in Abbey, 43. + death, 43. + education, 23. + narrative of voyage, 33. + patient mind, 45. + purity of mind, 29. + return to England, 33. + short sketches, 39. + study of barnacles, 34. + work double, 233. + + Deer horns, 138. + + Descartes and evolution, 12. + + Descent of man, 189. + + Determinants in nucleus, 238. + + Development of chick, 204. + + Development of pond-snails, 46. + + Devonian age, 173. + + Devonian fish, 173. + + DeVries and mutation, 246. + + Duckmole, 208. + + + E + + Early marriage, 272. + + Earth's age, 155. + + Ecstatic flight, 136. + + Egg-laying mammals, 208. + + Eimer and orthogenesis, 243. + + Elements of Geology, Lyell, 26. + + Emanuel Kant and evolution, 13. + + Embryo of chick, 203. + + Emerson and nature, 48. + + Empedocles and evolution, 8. + + English sparrow (see Sparrow, English). + + Environment in man, 258. + + Eugenic program, 269. + + Evening primrose and mutation, 246. + + Evolution since Darwin, 233. + + + F + + Feeble-mindedness, 264. + + Feet of mammals, 122. + + First living things, 165. + + Fish eggs, 145. + + Fish may freeze, 104. + + Fitz-Roy, Capt., and Beagle, 25. + + Freedom of teaching, 291. + + Fright paralysis, 108. + + Frog's long tadpole stage, 112. + + Frost and bluebirds, 61. + + Fur of seal, 100. + + Future evolution of man, 249. + + + G + + Galapagos Islands and evolution, 30. + + Geological periods, 158. + + Glyptodon and armadillo, 29. + + Goethe and evolution, 20. + + Graphite from plants, 168. + + Grasshopper's mouth, 93. + + Grasshopper song, 133. + + Groundhog and winter, 103. + + Growth of North America, 167. + + + H + + Haeckel advocates evolution, 42. + + Health certificates, 263. + + Henslow and Darwin's education, 24. + + Henslow suggests Darwin for Beagle, 24. + + Heredity and natural selection, 45. + + Heredity in man, 258. + + Homes, few animals have, 98. + + Homes, warm-blooded animals, 101. + + Horn of rhinoceros, 123. + + Horns of deer, 138. + + Horse and early man, 232. + earliest, 223. + neck, 229. + story of, 220. + three-toed, 227. + + Horseshoe crab, 171. + + How mammals developed, 192. + + Huxley at Oxford meeting, 42. + + + I + + Ichneumon fly, 142. + + Image of God, 288. + + Improving the environment, 259. + + Improving the stock, 261. + + Inheritance of acquired characters, 238. + + Insect's biting mouth, 93. + + Interpretation of Genesis, 284. + + Isolation, Jordan, 242. + + Isolation, Romanes, 242. + + Isolation, Wagner, 241. + + + J + + Java skull, 187. + + Jehovah confounding the nations, 289. + + Jordan and isolation, 242. + + Judgment, Michael Angelo, 289. + + Jukes family, 265. + + June-bug, 107. + + + K + + Kallikak family, 265. + + Kant and evolution, 13. + + Katydid's color, 111. + + Katydid's song, 133. + + Keeling Atoll and Darwin, 31. + + King Crab, 171. + + + L + + Lamarck and evolution, 17. + + Lampshells, 172. + + La Place's theory, 151. + + Leibnitz, and evolution, 13. + + Life from other planets, 162. + + Life in the past, 149. + + Life, its nature, 247. + + Linnæan Society and evolution, 40. + + Linnæus and fixed species, 15. + + Locust's song, 135. + + Lucretius and evolution, 10. + + Lung-fish, 176. + + Lyell's Geology, 26. + + + M + + Male birds brighter, 131. + + Male insects sing, 134. + + Malthus and population, 35. + + Mamma, significance of, 211. + + Mammals, egg-laying, 208. + how developed, 192. + + Man and God's image, 288. + early, and horse, 232. + growing better, 255. + + Man's ancestry, 250. + future evolution, 249. + + Mating and song, 133. + + Mating antics, 136. + + Meaning of Genesis, 284. + + Megatherium and sloth, 29. + + Mesozoic age, 178. + + Michael Angelo, Judgment, 289. + + Migration of birds, 103. + + Missing link, 187. + + Mizpah, 283. + + Modern teachers of biology, 291. + + Mongolian idiot, 265. + + Mosquito's bite, 97. + + Mosquito's mouth, 96. + + Mother-love, 217. + + Multiplication and evolution, 54. + + Mutation and DeVries, 246. + + + N + + Nature of life, 247. + + Nature of milk, 214. + + Natural selection explained, 45. + in brief, 36. + + Nebular hypothesis, 152. + + Neck of horse, 229. + + Neo-Darwinians, 237. + + Nests for warm eggs, 101. + + Number and position of breasts, 215. + + + O + + Odor as protection, 117. + + Opossum playing dead, 107. + + Origin of birds, 181. + feathers, 102. + flight, 122. + hair, 102. + life, 159. + lungs, 177. + milk glands, 212. + placenta, 210. + variations, 50. + + "Origin of Species" published, 41. + + Orthogenesis and Eimer, 243. + + Oxford meeting of British Association, 41. + + + P + + Palæozoic era, 170. + + Paley's Natural Theology, 87. + + Pangenesis, 236. + + Patagonia and its terraces, 29. + + Phenacodus, 185. + + Physical evolution of man, 254. + + Pithecanthropus, 188. + + Planetesimal theory, 155. + + Playing dead, 107. + + Playing 'possum, 107. + + Polygamy in animals, 137. + + Pond-snail, development of, 46. + + Potato worm, 142. + + Protective coloration, 109. + + Protoplasm, 164. + + Pterodactyl, 180. + + Puff adder, 107. + + Purpose and adaptation, 89. + + Purpose in nature, 88. + + + Q + + Quiet and escape, 105. + + + R + + Raining toads, 113. + + Religion and evolution, 74. + + Reptiles of Mesozoic, 179. + + Reproduction, asexual and sexual, 194. + in fishes, 196. + in frogs, 199. + in reptiles, 202. + + Rhinoceros horn, 123. + + Romanes and isolation, 242. + + Rooster finer than hen, 132. + + + S + + Saint Augustine and evolution, 11. + + Salamanders, 176. + + Sargent's picture, 289. + + Science and the book, 274. + + Science and theology, 280. + + Science, definition, 280. + + Seals and polygamy, 139. + + Sealskin and fur, 100. + + Sedgwick and Darwin, 24. + + Selection and evolution, 56. + + Sexual selection, 126, 128. + + Skunk's odor, 117. + + Sloth and megatherium, 29. + + Song and mating, 133. + + Sparrow, English, adapted to town, 66. + and hawks, 69. + and winter, 73. + eat varied food, 71. + eye-minded, 78. + feed young on insects, 72. + good qualities, 85. + has reached limit, 85. + in Philadelphia, 63. + introduction, 62. + lives near houses, 70. + nests early, 81. + nests often, 82. + once migratory, 80. + quarrels without animosity, 75. + sociable, 74. + spread of, 65. + stays over winter, 79. + successful, 83. + transported in cars, 67. + unafraid of man, 69. + wintering, 73. + + Sparrow, House, 62. + + Sphex wasp, 143. + + Spider cocoons, 139. + + Spider, young, 140. + + Spontaneous generation, 159. + + Stone lilies, 171. + + Story of the horse, 220. + + Struggle against enemies, 104. + for food, 91. + for shelter, 92. + for the individual, 90. + for the species, 91, 125. + + Sunfish and young, 196. + + + T + + Taste of toad, 118. + + Teeth of mammals, 98. + + Temperature of mammals, 99. + + Tertiary era, 185. + + Thayer, concealing color, 115. + + Theology and science, 280. + + Theology, definition, 280. + + Thomas Aquinas and evolution, 12. + + Three-toed horse, 227. + + Toad, bad taste, 118. + color, 112. + enemies, 113. + short tadpole stage, 112. + + Tomato worm, 142. + + Turtles and young, 202. + + Tusks of elephant, 124. + + Tussock worm, 64. + + Two methods of reproduction, 194. + + Types of insect mouth, 93. + + + U + + Understanding the Bible, 281. + + Underwing moth, 130. + + + V + + Variation and natural selection, 49. + by crossing, 53. + + Virchow and man's ancestry, 187. + + Vireo's color, 115. + + + W + + Wagner and isolation, 241. + + Wallace and evolution, 39. + + Warm-blooded animals, 99. + + Weissman and evolution, 235. + + Wilberforce, Bishop, and evolution, 41. + + Wintering of ground hog, 103. + + Wintering of mammals, 103. + + Wintering of squirrels, 103. + + Woodchuck, 103. + + Woodpecker's nest, 146. + + + Y + + Young growing finer, 272. + + + + +APPENDIX + +BIBLIOGRAPHY + + +In connection with each chapter, wherever this is possible, there are +four classes of references. First is named a small and inexpensive but +satisfactory book on the subject. Second, a more comprehensive book, +readily accessible and not unduly expensive. Then a few of the most +satisfactory reference books on the subject independent of cost or +ready availability. Fourth, a list of references to articles in the +eleventh edition of the Encyclopedia Britannica. + + +CHAPTER I. _Evolution before Darwin._ + +1. -- -- -- -- + +2. Biology and Its Makers, Locy. + +3. From the Greeks to Darwin, Osborn. Chapters 1, 2, 3, 19. + +4. Encyclopedia Britannica, 11th edition, article, _Evolution_, +section, _History_. + + +CHAPTER II. _Darwin and Wallace._ + +1. The Coming of Evolution, Judd. + +2. Charles Darwin, Poulton. + +3. Life and Letters of Charles Darwin, by his son, Francis Darwin. 2 +vols. + +My Life, A. R. Wallace. 2 vols. + +4. Encyclopedia Britannica, articles _Darwin_, _Wallace_. + + +CHAPTER III. _The Underlying Idea._ + +1. Evolution, Geddes and Thompson. + +2. The Origin of Species, Charles Darwin. + +3. The Evolution Theory, Weissmann. 2 vols. + +4. Encyclopedia Britannica, articles _Variation_ and _Selection_. + + +CHAPTER IV. _Adaptation for the Individual._ + +1. Colin Clout's Calendar, Grant Allen. + +2. Evolution and Animal Life, Jordan and Kellogg. Chapters 16, 19. + +3. Darwinism, Wallace. + +4. Encyclopedia Britannica, articles _Adaptation_, _Colours of +Animals_, _Hibernation_. + + +CHAPTER V. _Adaptation for the Species._ + +1. Colin Clout's Calendar, Grant Allen. + +2. Evolution and Animal Life, Jordan and Kellogg. + +3. Darwinism, Wallace. + +4. Encyclopedia Britannica, articles, _Metamorphosis_, _Song of +Birds_. + + +CHAPTER VI. _Life in the Past._ + +1. The Story of Our Continent, Shaler. + +2. Elements of Geology, Blackwelder and Barrows. + +3. The Story of Evolution, McCabe. + +4. Encyclopedia Britannica, article, _Geology_ (palæontological and +physiographical). + + +CHAPTER VII. _How the Mammals Developed._ + +1. -- -- -- -- + +2. Plant and Animal Children, Torelle. + +3. -- -- -- -- + +4. Encyclopedia Britannica, article, _Mammalia_. + + +CHAPTER VIII. _The Story of the Horse._ + +1. The Evolution of the Horse in America, Osborn, in _The Century_, +November, 1904. + +The Evolution of the Horse, Matthew. + +2. The Horse, Flower. + +3. Encyclopedia Britannica, article, _Horse_. + + +CHAPTER IX. _Evolution Since Darwin._ + +1. The Evolution of Living Organisms, Goodrich. + +2. Biology and Its Makers, Locy. Chapters 14, 18. + +3. Darwinism To-day, Kellogg. + +4. Encyclopedia Britannica, articles, _Romanes_, _Weissmann_, +_Mendel_. + + +CHAPTER X. _The Future Evolution of Man._ + +1. The Problem of Race Regeneration, Ellis. + +2. Inquiries into Human Faculty, Galton. + +3. Heredity, Thompson. + +4. Encyclopedia Britannica, articles, _Eugenics_, _Galton_. + + +CHAPTER XI. _Science and the Book._ + +1. -- -- -- -- + +2. The Origin and Permanent Value of the Old Testament, Skater. + +3. The Life and Literature of the Ancient Hebrews, Abbott. + +4. Encyclopedia Britannica, articles, _Genesis_, _Bible_ (Old +Testament Canon). + + +REVIEW QUESTIONS + +_Foreword._ 1. What is the purpose of this book? + +Chapter I. 1. What were some of the theories of the Greek +philosophers, and what shadowing of truth was there in their beliefs? +2. What was Lucretius's idea? 3. What were the explanations of Genesis +given by St. Augustine and by Thomas Aquinas? 4. What were theories of +Descartes, Leibnitz, and Kant? 5. How is the delay of the thought of +evolution accounted for? 6. What were the contributions of Linnæus, +Buffon, Erasmus, Darwin, Lamarck? 7. What check to progress was made +by Cuvier and Agassiz? 8. What phases of evolution were studied by +Goethe? + +Chapter II. 1. Sketch the life of Charles Darwin. 2. What advantages +did he derive from the "Beagle" expedition? 3. What is the theory of +Natural Selection, and how did Darwin arrive at it? 4. Describe the +Wallace and Wilberforce incidents. 5. What has been the progressive +attitude toward the Darwinian idea? + +Chapter III. 1. Explain Heredity as the conservative force of nature. +2. Explain Variation as the progressive tendency in nature. 3. In what +ratio is the Multiplication of animals? 4. How does the process of +Selection make for the survival of the fittest? 5. What three +possibilities are open to animals under a change of environment? 6. +What is the history of the English Sparrow in this country, and how is +his increase accounted for by his powers of adaptation? + +Chapter IV. 1. Show how the struggle for existence as affecting food, +results in adaptations in the individual. Give illustrations. 2. Do +the same for the results of struggle for shelter. 3. What are some of +the adjustments resulting from the need of protection from foes? + +Chapter V. 1. Discuss coloration. 2. How is sound used as an +attraction? 3. What are some of the other methods of attracting mates? +4. What are some of the specializations produced by polygamy? 5. +Describe some of the protections and provisions for the young. + +Chapter VI. 1. What is La Place's Nebular Hypothesis? 2. What is the +Planetesimal Theory? 3. What bases have been used for calculation of +the age of the earth? 4. Reproduce the Table of Geological Times. 5. +What is the Theory of Spontaneous Generation? 6. What is the theory of +life development from organic dust in space? 7. Discuss protoplasm. 8. +What was the probable growth of the North American continent? 9. What +is the nature of the fossils in the earliest layers of stratified +rock? 10. Describe the life of each of the three periods of the +Palæozoic era. 11. Do the same for the Mesozoic era. 12. What was the +effect upon life of the development of seasons and of climates? 13. +What physical characteristics of the earth helped in the development +of new animal forms in the Cenozoic era? 14. What has been the ascent +of man? + +Chapter VII. 1. Illustrate the asexual method of reproduction. 2. +Trace the two-parent method of reproduction upward from the simplest +forms. 3. What has been the development of the milk glands? 4. How +does the prolonged care of the young by the mother indicate the higher +development of the animal? + +Chapter VIII. 1. Describe the earliest known ancestor of the horse? 2. +What changes took place in the second stage of development? 3. What is +the form by the middle of the Tertiary period? 4. What was the size of +the late Tertiary horse, and how was the grinding power of the teeth +increased? 5. How was the early Quaternary horse adapted for speed and +for eating? 6. How is the extermination of the horse in North and +South America accounted for, and how was he introduced again? + +Chapter IX. 1. How extensive has the belief in evolution become since +Darwin's day? 2. How does the theory of Natural Selection fail in +accounting for Variation; how did Darwin try to amend his original +theory; and what is Weissmann's belief. 3. What second objection has +been brought against the theory of Natural Selection, and what have +been the contributions of Wagner, Jordan, and Romanes to the +discussion? 4. What is the third objection to Darwinism, and what is +the bearing upon it of the theory of Orthogenesis? 5. What is the +American and French tendency toward the belief that use is the cause +of the persisting of organs? 6. How did DeVries discover the +principle of mutation, and how does it apply to the discussion of +evolution? + +Chapter X. 1. What was the cause of the passing of the civilization of +Athens, of Judea, of Sparta? 2. What promise of uniform development is +evident to-day, and what are some of the hindrances? 3. What has been +the changing emphasis in the evolution of man? 4. How is man the +arbiter of his own destiny? 5. What is the task of the eugenist; how +is he trying to accomplish it, and what are some of the possibilities +suggested. 6. What is the promise for the future? + +Chapter XI. 1. What is the duty of the fair-minded person toward the +essential truths of religion and of science? 2. What two difficulties +lie in the path of reconciliation, and why should each century restate +its truths? 3. What three steps are desirable in studying the Bible? +Illustrate. 4. What is the essential truth of the early chapters of +Genesis, and what its glory? 5. Interpret the meaning of "creation of +man in God's image." 6. What is our duty to ourselves and our +children? + + + + + +End of the Project Gutenberg EBook of The Meaning of Evolution, by +Samuel Christian Schmucker + +*** END OF THIS PROJECT GUTENBERG EBOOK THE MEANING OF EVOLUTION *** + +***** This file should be named 29422-8.txt or 29422-8.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/2/9/4/2/29422/ + +Produced by Juliet Sutherland, Chris Logan and the Online +Distributed Proofreading Team at http://www.pgdp.net + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. 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You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: The Meaning of Evolution + +Author: Samuel Christian Schmucker + +Release Date: July 16, 2009 [EBook #29422] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK THE MEANING OF EVOLUTION *** + + + + +Produced by Juliet Sutherland, Chris Logan and the Online +Distributed Proofreading Team at http://www.pgdp.net + + + + + + +</pre> + + + + + +<div id="title_page"> +<h1>THE MEANING OF<br /> +EVOLUTION</h1> + +<div class="section_break"></div> + +<p class="by">BY</p> + +<p class="name">SAMUEL CHRISTIAN SCHMUCKER, Ph.D.</p> + +<p class="professor">PROFESSOR OF BIOLOGICAL SCIENCES IN THE<br /> +WEST CHESTER STATE NORMAL SCHOOL<br /> +WEST CHESTER, PA.</p> + +<div class="figcenter" style="width: 150px;"> +<img src="images/logo.png" width="150" height="129" alt="Logo" title="" /> +</div> + +<p><span class="press">The Chautauqua Press</span><br /> +CHAUTAUQUA, NEW YORK<br /> +MCMXIII</p> +</div> + + + + +<div class="section_break"></div> + +<div id="copyright_page"> +<p class="copyright">Copyright, 1913<br /> +By THE MACMILLAN COMPANY</p> + +<div class="thought_break"></div> + +<p>Set up and electrotyped. Published June, 1913</p> +</div> + + + +<div class="section_break"></div> +<div id="toc"> +<h2>CONTENTS</h2> + + +<table summary="Table of contents"> +<thead> +<tr> + <th>CHAPTER</th> + <th> </th> + <th>PAGE</th> +</tr> +</thead> +<tbody> +<tr> + <td> </td> + <td>A Foreword</td> + <td class="table_right"><a href="#Page_1">1</a></td> +</tr> +<tr> + <td class="table_right">I.</td> + <td>Evolution Before Darwin</td> + <td class="table_right"><a href="#Page_7">7</a></td> +</tr> +<tr> + <td class="table_right">II.</td> + <td>Darwin and Wallace</td> + <td class="table_right"><a href="#Page_21">21</a></td> +</tr> +<tr> + <td class="table_right">III.</td> + <td>The Underlying Idea</td> + <td class="table_right"><a href="#Page_44">44</a></td> +</tr> +<tr> + <td class="table_right">IV.</td> + <td>Adaptation for the Individual</td> + <td class="table_right"><a href="#Page_87">87</a></td> +</tr> +<tr> + <td class="table_right">V.</td> + <td>Adaptation for the Species</td> + <td class="table_right"><a href="#Page_125">125</a></td> +</tr> +<tr> + <td class="table_right">VI.</td> + <td>Life in the Past</td> + <td class="table_right"><a href="#Page_149">149</a></td> +</tr> +<tr> + <td class="table_right">VII.</td> + <td>How the Mammals Developed</td> + <td class="table_right"><a href="#Page_192">192</a></td> +</tr> +<tr> + <td class="table_right">VIII.</td> + <td>The Story of the Horse</td> + <td class="table_right"><a href="#Page_220">220</a></td> +</tr> +<tr> + <td class="table_right">IX.</td> + <td>Evolution Since Darwin</td> + <td class="table_right"><a href="#Page_233">233</a></td> +</tr> +<tr> + <td class="table_right">X.</td> + <td>The Future Evolution of Man</td> + <td class="table_right"><a href="#Page_249">249</a></td> +</tr> +<tr> + <td class="table_right">XI.</td> + <td>Science and the Book</td> + <td class="table_right"><a href="#Page_274">274</a></td> +</tr> +<tr> + <td colspan="2">Index</td> + <td class="table_right"><a href="#Page_293">293</a></td> +</tr> +<tr> + <td colspan="2">Appendix</td> + <td class="table_right"><a href="#Page_299">299</a></td> +</tr> +</tbody> +</table> +</div> + + + +<div class="section_break"></div> +<p><span class="pagenum"><a name="Page_1" id="Page_1">[Pg 1]</a></span></p> +<h2>A FOREWORD</h2> + + +<p>Before my window lies an enchanting landscape. It embraces a stretch +of open rolling country, beautiful as the eye could wish to rest upon. +The sun with its slanting rays is not giving it heat enough in these +winter months to make it blossom in its radiant beauty, but the mind +goes easily back through the few brown months to the time when the +field not far away was waving with its rich yellow grain so soon to be +food for those who planted it. Beyond this field lies an orchard +where, in regular and orderly rows, stand the apple trees whose bright +blossoms in the spring make the landscape so beautiful and whose fruit +in the fall serves so richly for our enjoyment. A little farther on, a +pasture is filled with sleek-coated cows, feeding quietly and +patiently until the evening when they will return to their stalls to +yield their rich milk. Still farther on lies a tract of forest. The +varied shades of the beeches, the tulip poplars and the chestnuts make +an exquisite contrast and give to the landscape its attractive +background framed in by a distant hill. Behind this hill flows a +mighty river carrying on its breast the ships by which we share<span class="pagenum"><a name="Page_2" id="Page_2">[Pg 2]</a></span> the +over-abundance of our own blessings with our brothers on the other +side of the sea, from whom in turn we receive of their overplus. +Beyond this teeming river lies a level stretch of fertile land and +then the mighty ocean. On one side of the scene runs a busy highway. +Along this men pass and repass, some on foot, others drawn by their +patient and submissive horses. Still others are carried by the +new-found power of the sunshine imprisoned beneath the rocks in the +oil that has been forming ever since the sun shone down upon the great +forests of the far distant past.</p> + +<p>In a pathway to one side, some children are playing. One of them has +laid upon the ground a rectangle of stones divided into four and her +little mind sees before her the house which is teaching her to get +ready for the work that shall come to her in later life. Meanwhile her +short-haired companion is prancing around astride a stick; he too, +little as he suspects it, is getting ready for life.</p> + +<p>It needs little reflection to realize that the scene has not always +been what it is. The underlying ground has surely been there longest, +its age vying only with that of the bounding ocean that beats upon the +shore and works the sand into fantastic stretches. The forest has been +there long and so has the stream; the road perhaps ranks next in age; +then come the<span class="pagenum"><a name="Page_3" id="Page_3">[Pg 3]</a></span> orchard trees, and most recent of all the waving grain. +People come and go but form no stable part of this landscape. We know +how the grain came to be there, and we understand the orderly +arrangement of the orchard trees; the road too we can explain. How +came the stream there, and how the forest trees? Have they always been +there, or did they too have a beginning? Was there a time when there +was no ocean? When was this time? How came they there?</p> + +<p>When the lisping lips of my young child asked me, "Papa, who made me?" +I told him "God," and he knew enough and was content with his +knowledge. After a while he grew older and his inquisitive spirit +began to puzzle with the question of how God had made him. When his +growing mind was ready for the new knowledge I took him to my side and +told him the great mystery of life. I told him how he owed to his +father and to his mother the beginnings of his life, how God gave him +to us. Now a new era opened in his childish mind. As he grows on to +greater maturity he cannot help wondering how the first man was made, +how the trees, and the world came to be. He is no longer satisfied +with the simple statement that God made them. His eager mind wants to +know, if may be, how God made them.</p> + +<p>So, in the distant past, in the childhood of our race, the question +was asked, "Who made us?" and the an<span class="pagenum"><a name="Page_4" id="Page_4">[Pg 4]</a></span>swer was "God." Men formed their +simple conception at that time of how He did it. As the centuries +rolled by and the children of men have learned from creation the story +of its origin a riper and richer knowledge has given them a broader +and finer conception. No less does the reverent student believe that +God created the earth, but he no longer thinks of God as working, as +man works. He no longer feels that it is impious to attempt to read +God's plan in His work; to see how this work has arisen, to see, if +may be, what there is ahead.</p> + +<p>This is one of the tasks to which science is now giving itself. The +answer is uncertain and halting. A few things seem clear; others seem +to be nearly certain; of still others we can only say that for the +present we must be content with the knowledge we have. But if we take +the best we have and work over it thoughtfully and carefully, the +better will slowly come, and in time we shall know far more than we +now suspect. Meanwhile, it is the attempt of this book to give to +people whose training is other than scientific some conception of this +great story of creation. Without dogmatic certainty but without +indecision it tries to tell what modern science thinks as to the great +problems of life. It tries to describe the possible origin of animals +and plants, their slow advance, the length of their steady uplift, the +forces that<span class="pagenum"><a name="Page_5" id="Page_5">[Pg 5]</a></span> brought it about. It tries to tell a little of the men +who have helped to develop the great idea of evolution, of the great +men who persuaded the scientific world of its truth, and of the later +minds that are modifying and enlarging the idea of the master +evolutionist. It tries to tell what science perhaps vaguely hopes as +to the future. What are we to be? Can we help the great advance?</p> + + + +<p><span class="pagenum"><a name="Page_6" id="Page_6">[Pg 6]</a></span></p> +<div class="section_break"></div> +<p><span class="pagenum"><a name="Page_7" id="Page_7">[Pg 7]</a></span></p> +<h2 class="meaning">The Meaning of Evolution</h2> + + + +<div class="section_break"></div> +<h3>CHAPTER I</h3> + +<p class="chapter_subhead">Evolution Before Darwin</p> + + +<p>Ever since men have been able to think they must have puzzled out for +themselves some way of accounting for their own beginnings. Every +savage tribe with whom we have any intimate acquaintance has some +story that accounts for the origin of the tribe at least, and often +for the beginning of the world. These stories are handed down from +generation to generation and are scarcely questioned in the thought of +most men. In early Greece there was a succession of men whom the world +calls philosophers. These men thought earnestly and deeply on all +kinds of questions. Their method was not our method. The plan of +making a long series of observations, before coming to any conclusion, +was not the habit of their minds. They reasoned out on general +principles what seemed to them must have been the origin of the world. +It is not strange that among these should come, now and then, some one +who in some<span class="pagenum"><a name="Page_8" id="Page_8">[Pg 8]</a></span> passage or other should show that there had come to his +mind at least a glimmer of the thought that was later to develop into +the great idea which the modern world calls evolution.</p> + +<p>Among the earliest of these was Anaximander, who lived 600 years +before Christ. He thought that the earth was at first a fluid. +Gradually this fluid began to dry and grow thicker, and here and +there, where it thickened most, dry land appeared. When this dry land +had become firm enough to serve as his home, man came up from the +water in the form of a fish. Slowly and gradually the fish, struggling +about on the land, gained for himself the limbs and members he needed +for his new situation and developed into a man. After him other +animals came up in much the same fashion, then the plants, until the +whole world was clothed with its present inhabitants.</p> + +<p>One hundred and fifty years later Empedocles announced a new thought. +He said that in the beginnings there were all sorts of strange, +incomplete, and misjointed monsters which swarmed upon the earth, +having sprung up out of the earth itself. Each was a chaos of the +limbs which afterward were to belong to other animals which needed +them more. Slowly and gradually an interchanging came about by which +appropriate limbs fastened themselves to the proper animals. The last +of these misjointed creatures is the<span class="pagenum"><a name="Page_9" id="Page_9">[Pg 9]</a></span> one known as the centaur, +half-man—half-horse. After a while, when all the members had found +their proper places, the animals were complete. In one respect this +opinion foreshadowed our later idea. It suggested that the more +perfect animals had arisen out of the less perfect and that the change +came gradually.</p> + +<p>Then came Anaxagoras, who was the first to believe that there was +intelligent design back of the creation of animals and of plants. He +thought there had originally been a slime in which were the germs of +all the later plants, animals, and minerals, mixed in a chaos. Slowly +order arose. Out of the mixture settled first the minerals forming the +earth, with the air floating above it, and above the air was the +ether. Out of the air the germs of plants settled upon the earth, and +vegetation covered the mineral floor. Then from the ether came the +germs of animals and of men. These settled among the plants and sprang +up into the animals of the world, as well as the people.</p> + +<p>The greatest scientific thinker of early Greece was Aristotle. He had +lived by the seashore and knew better than any other man of his times +the exquisite seaweeds and the still more beautiful marine animals. He +was the first to think of them as a linked series, the higher +developing out of the lower under the<span class="pagenum"><a name="Page_10" id="Page_10">[Pg 10]</a></span> pressure of what he called a +perfecting principle. Out of the inanimate rocks had sprung the marine +plants—the seaweeds. From these had developed first "plant animals" +like the sea anemones and the sponges. These grew attached to the +rocks, as plants do. With higher development came locomotion, with +ever-increasing energy. At last man arose, the crown of all creation. +Presiding over all this advance is the "efficient cause," God. +Aristotle rejected entirely the earlier ideas that any of this work +came about by chance. He was certain of the existence of plan and +purpose in the development.</p> + +<p>Just a little before the time of Christ the Latin poet, Lucretius, +wrote a poem on "The Nature of Things." Here he describes how in the +early years the beginnings of things in small, disjointed fashion +moved about among each other at first in utter confusion, each trying +itself with the other. After many trials the proper members came +together. When they had been thus placed the warmth of the sun shining +down upon the earth helped the earth to reproduce the same sort of +creatures. So living things came up and flourished. The poem expresses +many beautiful ideas, but the underlying conceptions lack the unity +and grandeur that marked Aristotle's work, which later was the potent +influence in shaping men's minds. It died out after a while, only to +awake in the Re<span class="pagenum"><a name="Page_11" id="Page_11">[Pg 11]</a></span>naissance with marvelous vitality, starting the world +to think afresh great thoughts that would not die, but would grow from +that time on with ever-widening scope.</p> + +<p>Among the Jews and early Christians the stately and beautiful account +in Genesis sufficed for all the needs of minds fully occupied with +other questions. With the growth of philosophy among Christian minds +again came the need of a satisfactory solution. St. Augustine was +probably the greatest of the so-called "Fathers" of the church. His +mind was eminently philosophical, and he was learned in the writings +of the older Greeks. He believed the language of Genesis to mean that +in the beginning God planted in chaos the seed that afterward sprang +up into the heavens and the earth. He further says that the six days +of creation were not days of time, but a series of causes, and that, +in the order described as these six days, God planted in chaos the +various beginnings of things. These in the fullness of time sprang up +into the world as we know it now. The problem was not a question about +which the church cared to trouble itself, and with the oncoming of the +Dark Ages the whole matter dropped nearly out of the thoughts of men.</p> + +<p>When the times began to lighten we find the schoolmen, among the +greatest of whom was Thomas<span class="pagenum"><a name="Page_12" id="Page_12">[Pg 12]</a></span> Aquinas. Referring especially to the +authority of his master, St. Augustine, he says that it would be easy +mistakenly to believe that the author of Genesis meant to convey the +idea that on each of the six days certain acts of creation were +performed. It is quite evident, thinks Aquinas, that in those early +times God only created the germs of things and put into the earth +powers which should later become active. After the Creator had thus +endowed the earth he rested from the work, which proceeded to develop +under the influence of these first germs.</p> + +<p>Nearly four hundred years later, when Europe had finally awakened out +of the deep and refreshing sleep in which it had fortunately forgotten +much of the past, a new era dawned and modern thought began. +Immediately men commenced to busy their minds with broader problems +than they had been discussing since the time of the Greek +philosophers. The hand of tradition, however, was heavy on them still. +They dreaded to run counter to authority, and did not dare think +unrestrainedly. Descartes shows us how we can understand things better +if we will imagine a few principles by which it will be easy to +account for things as they are. Then he carefully elaborates these +principles as they occur to him; but he has no sooner done so than he +takes care to add, "Of course, we know the earth was not made in this +way."</p> + +<p><span class="pagenum"><a name="Page_13" id="Page_13">[Pg 13]</a></span>A little later the philosopher, Leibnitz, believed in an orderly +creation that had advanced by regular degrees, and that the lower +animals had thus developed into the higher. He adds interestingly that +there are probably on some other planets animals midway between the +ape and man, but that nature has kindly removed such animals from the +earth in order that man's superiority to the apes should be entirely +beyond question.</p> + +<p>By the middle of the eighteenth century men had begun to think more +fearlessly. The great Emanuel Kant wrote in his younger and less timid +years, "The General History of Nature and Theory of the Heavens." The +great Newton had by his law of gravitation brought order into the +heavens. Kant looked longingly for a greater Newton, who should find a +similar unity in the animal world. He saw the wonderful likenesses +between animals that the anatomist, Buffon, had recently pointed out. +He believed there must somehow be blood relationship between all +animals. He tried hard to conceive of some underlying natural cause by +which all could have come about. As he grew older and his mind became +more cautious he came to think the matter deeper than the human mind +could ever fathom. He gave up the hope and believed the problem of +animal origin and derivation would forever remain insoluble. He +feared<span class="pagenum"><a name="Page_14" id="Page_14">[Pg 14]</a></span> there was not in man the power to conceive his own origin.</p> + +<p>If we ever wonder why it took so long before the thought of evolution +should have fully dawned upon the world, the answer is not far to +seek. No student of Natural History in ancient or medieval times had +the faintest conception of the enormous number of animals and of +plants in the world. The old Greek or Roman student of Natural History +gives no evidence of knowing more than a few hundred animals. Men have +named to-day, with systematic Latin names, hundreds of animals for +every one that Pliny ever knew, and he knew more than any other man of +early times of whom record has come to us.</p> + +<p>In early days men who traveled into foreign countries brought back +accounts of what they saw. The whole Natural History of ancient times +was filled with the most absurd and ludicrous stories of all sorts of +things to be seen in distant lands. Sir John Mandeville tells tales +almost as imaginative and quite as amusing as those attributed to +Baron Munchausen.</p> + +<p>Upon the great awakening of the fifteenth century, with its new study +and its wide-ranging travel, an entire change came over the human +mind. Men who journeyed into far countries brought back with them not +only accounts of what they saw, but, so far as might be, the things +themselves. Collections of plants<span class="pagenum"><a name="Page_15" id="Page_15">[Pg 15]</a></span> and of such parts of animals as +could be readily preserved soon began to accumulate in every great +center of Europe. It was only a question of time when such +acquisitions must be arranged and classified, but as yet there was no +system by which this could be done. The great Swedish botanist, +Linnæus, who lived in the eighteenth century, first taught us to give +to each animal and plant two Latin names, the first of these to be the +name of the group, known as a genus, to which it belongs, the second +to be the name of that sort, or species, of animal. The cat, for +instance, is <em>Felis catus</em>, the lion <em>Felis leo</em>, the tiger <em>Felis +tigris</em>, and so on. Linnæus then arranged the genera (plural of genus) +into families, and these families into orders and so classified the +animal and plant world as far as he knew it. In his earlier years +Linnæus thought of each species as being utterly apart and distant +from any other. He believed it had been so from the first, each +species having sprung in its complete form from the creative hand of +God. In later life he came to show some evidence of the belief in +development, but his great work is all built on the idea of the entire +fixity of species.</p> + +<p>About this time we find in the writings of Buffon, the French +naturalist, many indications of an idea approaching our modern +conceptions of evolution. He felt sure the pig could not have been a +special crea<span class="pagenum"><a name="Page_16" id="Page_16">[Pg 16]</a></span>tion, because he had four toes, two of which, with all +their bones and their hoofs, are quite useless to him. We now call +these toes "vestigial," and know the pig's ancestors used them, +walking on four toes and not on two, as at present. Buffon believed +there were degenerations as well as developments, and considered the +ape a degenerate man. He conceived these changes to be brought about +by what he called the favors and disfavors of nature. He varied much +in his opinions in various parts of his career and occasionally is +smitten either with conscience or with fear of authority. Then he goes +back and says it is all a mistake and each animal is the product of a +special act on the part of the Creator.</p> + +<p>A little later, in England, Erasmus Darwin, the grandfather of Charles +Darwin, who was subsequently to establish the evolution theory, wrote +a long and elaborate poem called the "Temple of Nature." In this we +find a remarkable prevision of many of the principles which were +afterward to be warmly advocated and disputed during the growth of the +idea of evolution.</p> + +<div class="poem"><div class="stanza"> +<span class="i0">"Hence without parents by spontaneous growth,<br /></span> +<span class="i0">Rise the first specks of animated life.<br /></span> +</div><div class="stanza"> +<span class="stars">* * * * * * *<br /></span> +</div><div class="stanza"> +<span class="i0">Thus as successive generations bloom<br /></span> +<span class="i0">New powers acquire and larger limbs assume."<br /></span> +</div></div> + +<p><span class="pagenum"><a name="Page_17" id="Page_17">[Pg 17]</a></span>Erasmus Darwin recognized the struggle for existence, but he saw in it +only a check against overcrowding, and not an active factor in the +development as his grandson Charles came to see it. It is possible the +elder Darwin's views might have been taken more seriously had he not +clothed them with the form of verse. In these days it seems quite +ludicrous to think of giving to the world a new scientific concept or +a new phase of philosophy in verse.</p> + +<p>The beginning of the nineteenth century gives us the first really +great contribution to the idea of evolution. Under more favorable +surroundings, this idea would have budded and become the parent stock +of our modern theories. The chill frosts of adverse criticism by those +in authority in science nipped the budding idea and so set it back +that only of late years have men come to realize its strength and +power. The Chevalier de Lamarck, serving in Monaco, was attracted by +its rich flora to the study of botany. Coming later to Paris, he +became acquainted with Buffon and was led by him to publish a Flora of +France, using the Linnæan system of classification. He was appointed +to the chair of zoölogy in the Jardin des Plantes, and was given +especial charge of the invertebrate animals, comprising all the +members of the animal kingdom except those with backbones. After +seventeen years of work over these forms, dur<span class="pagenum"><a name="Page_18" id="Page_18">[Pg 18]</a></span>ing which he wrote +several books describing them, he finally published the great work on +which his fame depends. This was the "Philosophie Zoölogique." In this +treatise he taught that the animal kingdom is a unit and that all its +members are blood relations; that the members vary with varying +conditions; that this variation results in continued advance. In all +of these points Lamarck is at one with modern thought. His idea of the +method by which the variation comes about has been accepted and +rejected; modified, reaccepted, and again rejected.</p> + +<p>Lamarck's conception of the cause of progress was somewhat as follows: +The desire for any action on the part of an animal leads to efforts to +accomplish that desire. From these efforts came gradually the organ +and its accompanying powers. With every exercise of these powers the +organ and its corresponding function became better developed. Every +gain either in function or in organ was transmitted to those of the +next generation, who were thus enabled to start where their parents +left off. The general environment constantly gave the stimuli that led +to the adaptive changes.</p> + +<p>American zoölogists have been especially inclined toward Lamarck's +ideas. Until Weissmann startled the scientific world with his sharp +denial of the possibility of transmitting to offspring any growth +ac<span class="pagenum"><a name="Page_19" id="Page_19">[Pg 19]</a></span>quired by the parents, all seemed well. There is a tendency now to +insist once more that slowly and gradually, in some perhaps as yet +unexplained way, external factors do influence even egg cells, and +gradually acquired characters do reappear in the offspring.</p> + +<p>The blighting setback these views suffered came from the criticisms of +Baron Cuvier. This genuinely remarkable man had built up the study of +comparative anatomy. To him students flocked from all sides. Among +these one of the most brilliant was Agassiz, the Swiss naturalist, who +later came to this country, filled with Cuvier's ideas. This great +teacher believed that species are fixed. He knew better than any man +of his times the wonderful similarity in structure between animals of +a given class. He attributed this not to any real blood relationship +between the animals. They were alike because they had been made by the +same Creator. This great Artificer worked along four main lines, and +hence animals could be divided into four groups. Many who have studied +text books on zoölogy written in this country by Agassiz and his +followers will remember the four classes—Radiates, Articulates, +Mollusks, and Vertebrates. Agassiz was such a wonderful teacher and so +genial and so lovable a man that his opposition to evolution held back +the advance of the Darwinian idea in America as Cuvier's influence<span class="pagenum"><a name="Page_20" id="Page_20">[Pg 20]</a></span> +had held back the Lamarckian idea in Europe. For the brilliant Cuvier +simply laughed before his students at each "new folly" of Buffon and +of Lamarck. Under this ridicule the influence of both men withered and +died.</p> + +<p>A little later the great poet, Goethe, turned his attention to the +problem of evolution, giving an interesting account of the +metamorphoses of plants. He declared, also, that the human skull is a +continuation of the backbones of the neck, and that these bones have +been transformed into the present skull. But his great genius as a +poet drew his attention into other fields. Haeckel points out that if +Goethe had known Lamarck's work his genius would have gained for the +"Philosophie Zoölogique" the interest and respect of the reading +world. But Cuvier laughed it out of court, and only in comparatively +modern times, since Darwin's work has set the world thinking anew, is +Lamarck's career recognized at its true value. Lamarck should have +been the founder of the evolution theory. But the time was not quite +ripe, and it remained for Charles Darwin to announce his idea, +sustained and fortified by years of careful observation and thoughtful +reflection.</p> + + + +<div class="section_break"></div> +<p><span class="pagenum"><a name="Page_21" id="Page_21">[Pg 21]</a></span></p> +<h3>CHAPTER II</h3> + +<p class="chapter_subhead">Darwin and Wallace</p> + + +<p>We have seen in the last chapter that whenever men have actively +thought they have attempted to explain the origin of plants and +animals as well as of themselves. No one who wrote previous to the +time of Charles Darwin had expressed any idea concerning this matter +with force enough to convince any large portion of the thinking world. +If Lamarck had fallen on better times, if the great Cuvier had not +laughed him to scorn, if Goethe had found him out and made him known +to the world, evolution might have come into its own sooner. None of +these conditions arose, and it remained for Charles Darwin to give to +the world in clear and cogent form the thought of evolution. He +gathered so much material before he expressed his opinions, and looked +at the matter from so many sides that, when he published his results, +he had foreseen most of the objections which were subsequently to +arise in opposition to his announcement. Charles Darwin is recognized +to-day as the father of the evolutionary movement.</p> + +<p><span class="pagenum"><a name="Page_22" id="Page_22">[Pg 22]</a></span>It has been sometimes said in recent years that Darwinism is dead, and +there is a sense in which this is true. Unmodified and unassisted +natural selection is not to-day considered by most scientists a +sufficient agent for producing evolution. But everyone connected with +the subject acknowledges Darwin as the master, and says that it was +his work which converted the world to a belief in evolution. We can +have no better preparation for an intelligent understanding of this +subject than to consider carefully the life of this remarkable man and +the circumstances under which he came to his epoch-making conclusions.</p> + +<p>Evolution has taught us to attempt as far as may be to account for man +on the basis of his heredity or of his environment. It is interesting +to note that both of these factors in Darwin's case were entirely +favorable. In the latter part of the eighteenth century Erasmus Darwin +had given to the world an astonishing poem in which he anticipated not +a little of the thought which his more famous grandson was to make so +widely known. Josiah Wedgwood had learned to make for England her most +famous pottery, no quality of which was more widely recognized than +the sterling patience with which it was made. Erasmus Darwin, with his +scientific proclivities, and Josiah Wedgwood, with his sturdy common +sense and patient workmanship, united to give Charles Darwin his<span class="pagenum"><a name="Page_23" id="Page_23">[Pg 23]</a></span> +inherited tastes, for he was a grandson of both. Born in 1809, on the +banks of the Severn in England, Charles Darwin was the delicate son of +a practicing physician of modest but sufficient means. Owing to his +lack of early vigor, Darwin spent much time in the open air, and in +his excursions about his home was chiefly interested in collecting +beetles. This taste, which lasted through all his young manhood, is +the one early indication of the traits that were later to develop. At +first in the day-school and later in the preparatory school Charles +Darwin was anything but a satisfactory student. Even a kindly desire +later to make the most of him makes it impossible to find traces of +any especial fondness for earnest study. He himself believed his +education to have been nearly useless, although he doubtless +under-estimated its value. At the age of sixteen he went to Edinburgh +at his father's desire, to study medicine. The sight of the +dissecting-room nauseated him completely, and he refused to continue +working in it. Later an operation which he witnessed in a clinic at +the hospital sickened him so thoroughly that he declined to attend +further operations. It became evident that the young man was not +adapted to the life of a physician. The next move was to educate him +for the church, and for this purpose, at the age of nineteen, he went +to Cambridge. Here it soon appeared that he was no<span class="pagenum"><a name="Page_24" id="Page_24">[Pg 24]</a></span> better adapted to +the ministry than he was to the practice of medicine, and his +university career went on in very desultory fashion. Most of his work +was distinctly neglected, but two of the men he met there were to +influence largely his future life. Henslow, the botanist, was +unusually fond, for a professor in those days, of work in the field. +Charles Darwin's tastes coincided with those of Henslow, with whom he +formed an intimate friendship. He was always welcomed as a companion +on the field trips. Though he studied little of botany in the +classroom or laboratory, he was constantly with Henslow or with +Sedgwick in the field. Sedgwick was the professor of geology, and of +him Darwin was particularly fond, and under him did much the largest +amount of his study. When he came up for graduation he ranked tenth of +those who "did not go in for honors," a not very remarkable class +standing. He was still required to put in two years of residence, and +during this interval he spent most of his time with Sedgwick in the +study of geology in the field. Returning to his home after a +geological trip into Wales, Darwin found awaiting him a letter from +Henslow, offering him an appointment that opened to his ardent mind +the door to a career after his own heart.</p> + +<p>The British nation, being the greatest commercial nation of the globe, +has the greatest need for accurate<span class="pagenum"><a name="Page_25" id="Page_25">[Pg 25]</a></span> charts of all the seas. Frequently +she has sent out great charting expeditions to various parts of the +world. One of these was to go out in Her Majesty's ship, <em>Beagle</em>, for +a voyage around the world. Captain Fitzroy was in command, and he was +especially commissioned to map the coast of South America from La +Plata to Cape Horn and up the western side. In addition to this work, +by carrying a set of accurate chronometers, he was to check up the +longitude of the various ports to be visited in this circumnavigation +of the globe. It was customary on such expeditions to carry a young +man whose duty it was to study the natural history of the countries +visited on the trip. The salary of such a naturalist was so small that +an experienced man could scarcely afford to take the place. Therefore +the appointment usually went to a man rather of promise than of +achievement. Through Henslow's influence, Charles Darwin was offered +this position in 1831. Darwin hastened to obtain his father's +permission, but the elder Darwin at first declined to consider the +matter. He felt that his son had not made such use of his time at the +university as warranted the hope that much could be expected of such a +journey. He believed it necessary that Charles should have some means +of earning an adequate living before he could think of devoting his +time to science. Charles found an efficient advocate<span class="pagenum"><a name="Page_26" id="Page_26">[Pg 26]</a></span> in the person of +his uncle, Josiah Wedgwood, Jr. Together they persuaded the father of +the propriety of giving to Charles this opportunity to follow out his +real tastes and ambitions. Accordingly, at the age of twenty-two, we +find him embarked on a journey around the world. In the cabin of the +<em>Beagle</em> he had abundant time, in his long sail across the Atlantic, +to read the two volumes of Lyell's "Elements of Geology," which +Henslow had handed him, with the suggestion that he read it, but on no +account believe it. Filled with the love of geology as Darwin was, +this epoch-making book was exactly the stimulus needed. Lyell had just +begun to persuade the world that to understand the past we must study +the present. In the forces now at work he saw cause enough to account +for all the history of the past of the earth.</p> + +<p>There is little doubt that this book was one of the most potent +factors in determining the bent of Darwin's mind. His entire +educational experience had failed to appeal to him. It is fortunate, +we now know, that this was the case. If the university course of the +time had really seized him it would have made but one more student +like hundreds it was turning out each year. For most of us this is the +happy event. Now and then comes the rare spirit to whom all of this +fails to appeal because he is ready for something better. Such was the +spirit of Charles Darwin. He<span class="pagenum"><a name="Page_27" id="Page_27">[Pg 27]</a></span> started on his journey with a mind +singularly free from prepossessions. In the long hours of this sailing +voyage across the Atlantic Ocean Darwin had time to read and ponder +Lyell's weighty words. By the time he reached the Brazilian shore he +was filled with Lyell's conception that the present is the child of +the past, developing out of it in orderly sequence. Lyell expressly +denied that this is true of the animal and plant world. He applied it +only to the face of the earth, with its mountains of uplift and its +valleys of erosion. But the underlying principle of an orderly +development under the action of natural causes was there. In Darwin's +mind this at once found acceptance, and was destined to a fruition its +author had expressly disclaimed.</p> + +<p>The narrative of this voyage, as subsequently written, describes the +islands visited by the <em>Beagle</em> in crossing the Atlantic Ocean. The +contrast between the simple and general interest in these islands and +the care with which Darwin described the Galapagos and the Keeling +Atoll visited later in the voyage are speaking evidence of the rapid +development going on in the mind of the young naturalist.</p> + +<p>Reaching the shore of South America, Darwin first turns to its +geology. But before long the animal life attracts his attention. In +the Brazilian forest Darwin had his first experience of the wealth of +animal and<span class="pagenum"><a name="Page_28" id="Page_28">[Pg 28]</a></span> plant life in the tropics, and, like all naturalists, he +was very enthusiastic over it. Among the animals that particularly +attracted his attention was the sloth, a peculiar creature climbing +slowly about the trees, small of size and sluggish of habit. Another +animal that interested him greatly was the little armadillo with its +interesting habit of curling up in its plated skin.</p> + +<p>Captain Fitzroy soon finished what work he was required to do in this +neighborhood, and Darwin was called back to the <em>Beagle</em> to continue +his voyage. When they arrived at the mouth of La Plata their most +serious work began. Here there was much tedious charting for Fitzroy, +and Darwin could now leave the vessel for a lengthy trip on shore. +This was doubly welcome. Seasickness was nearly constant with Darwin +while on this entire voyage and every opportunity to work on land was +eagerly seized. This region, too, was rich in objects of interest and +in strange people. While exploring the pampas, beyond Buenos Ayres, +Darwin came across the skeletons of the great mammals some of which +Cuvier had previously described. He studied these bones with much +care, and recognized at once in the megatherium a great similarity in +structure to the sloth he had seen in Brazil. The enormous skeletons +of the glyptodons struck him also as strangely similar to that of the +ar<span class="pagenum"><a name="Page_29" id="Page_29">[Pg 29]</a></span>madillo. One evening, seated alone in the broad expanse of the +pampas, the idea suddenly swept over him, stimulated, of course, by +his study of Lyell: "Can it be that the little armadillo and the sloth +of to-day are the degenerate descendants of the enormous megatherium +and glyptodon of the past?" But his mind was not yet ready to accept +so bold an idea and he swept it aside.</p> + +<p>The people of this wild neighborhood interested Darwin very greatly, +and he describes them with care. In this connection a charming trait +of Darwin's character comes beautifully in evidence. The absolute +purity of his mind, his utter freedom from grossness, shows clearly in +his account of the first really semi-civilized people he had ever +seen.</p> + +<p>A little later, while exploring Patagonia, Darwin noticed the +terrace-like formation of that desolate country. A flat near the sea +was succeeded by a rapid rise, then came another flat. Three of these +terraces in succession stretch back toward the Andes. At the base of +the high terraces Darwin found marine shells, largely similar to those +of the ocean beach so many miles to the east. His study of Lyell led +him to suspect at once that this portion of South America had been +raised in successive stages out of the bed of the Pacific. When they +passed around Cape Horn and up the western coast he hunted for<span class="pagenum"><a name="Page_30" id="Page_30">[Pg 30]</a></span> +similar beach marks on the sheer western face of the Andes, and found +them without difficulty, confirming his idea of the recent rise of +this end of the Andean chain.</p> + +<p>The <em>Beagle</em> continued its voyage up the western coast of South +America until it reached Peru. Once more the abundance of tropical +life is under Darwin's eyes, but now it is the life of an entirely +different section. The dry climate of Peru furnished him with an +environment distinctly unlike that of the moist Brazilian forest. He +collects now with avidity, gathering especially insects and birds. +Then the ship turned its prow westward across the Pacific, only to +stop five hundred miles out at the Galapagos Islands. This little +group he studied intensely, collecting large numbers of insects and +birds. He had not worked over his collection long before he realized +that each island in the group had peculiarities which marked its +animals from those of any other island. Whenever two islands were +close together in the group the differences in their fauna were found +to be comparatively slight. If, however, he examined the animals from +two islands lying at opposite ends of the group, the differences were +always considerably greater. There was, however, a strong general +resemblance among them all and a distant though not so strong +resemblance to the corresponding animals of the Peruvian<span class="pagenum"><a name="Page_31" id="Page_31">[Pg 31]</a></span> coast. On +leaving the Galapagos group, Charles Darwin writes in his diary the +suggestive observation that this little group of rocky islands seems +to be one of the greatest centers of creative activity. It was this +interesting resemblance of the animals of these islands to each other +and to those of the Peruvian coast that finally persuaded Darwin that +they were all related and were all descended from those of Peru. For +the rest of his life, with an intensity which increased with each +year, Darwin persisted in a patient search for the possible agencies +by which such change could have been brought about. The problem, +however, was temporarily eclipsed by a pressing geological question +aroused by his visit to the Keeling Atoll. Here his investigation of +coral reef formation absolutely captivated him. In the case of most +coral islands in the Pacific Ocean the reef exists as a circle of +coral enclosing a lagoon of water. In the center of this lagoon stands +commonly a rocky island. It is plain that this is the foundation on +which the coral built. But, in the case of the Atoll, the coral ring +was present and so was the internal lagoon, but there was no rocky +island. The key to the solution came with an interesting discovery. +Darwin began to put down a grappling iron on the outer side of the +reef and to drag up coral. The farther away from the reef he went the +deeper was the water from whose bottom he<span class="pagenum"><a name="Page_32" id="Page_32">[Pg 32]</a></span> pulled the coral. What at +first puzzled him was the fact that so long as he dragged up his coral +from depths of a hundred feet or less the coral was alive. Whenever he +went to depths of much more than a hundred feet, his coral was always +dead, though he was evidently pulling it from situations in which it +had grown. Then Darwin remembered the rising Andes, lifting themselves +out of the bed of the Pacific. Here was the correlated movement. The +bottom of the ocean here was sinking. As it sank it dragged down the +corals with it. But the descent was so slow that new corals could +build on top of the others fast enough to keep the reef up to the +surface of the water. At the rate of growth of coral, this would seem +to mean that the bottom could be sinking at a rate of only a few feet +a century. But while the reef could keep up to the surface, the rocky +island must slowly sink. Darwin inferred that there must be a rocky +summit within the lagoon, below the surface of the water. A little +sounding soon discovered this island, and the verification of Darwin's +theory of coral reef formation was at hand. The description of this +Atoll and of his theory of its formation won for Darwin the esteem of +geologists when he later presented it in book form.</p> + +<p>The voyage was continued around the Cape of Good Hope. Pursuing the +usual course of sailing<span class="pagenum"><a name="Page_33" id="Page_33">[Pg 33]</a></span> vessels, the <em>Beagle</em> touched once more at +Brazil, returning home to England in 1836, after an absence of five +years. Charles Darwin himself believed this trip to have been both his +education and his opportunity. He had started on it a rather careless +and indifferent student. He returned from it the most painstaking and +patient naturalist the world has ever known. His father, who had +hardly consented to his going because he believed him not stable +enough to be intrusted to his own devices for so long a period, was +profoundly moved at the sight of him on his return. Believing in +phrenology, as did many of the physicians of his time, his father +turned to his mother and said, "Look at the shape of his head; it is +quite altered"; which, translated into the language of to-day, would +read, "How wonderfully the young man has developed."</p> + +<p>A part of Charles Darwin's duty to the British Government was to write +a narrative of the voyage, and this account of his trip upon the +<em>Beagle</em> is one of the great classics of travel in the English +language. It won the confidence and respect of a wide circle of +readers. In his next book he published his observations made at the +Keeling Atoll and announced his theory of the formation of coral +islands. This was a distinctly scientific investigation, and it won +such immediate favor among geologists as to increase materially the +young man's reputation. No one man<span class="pagenum"><a name="Page_34" id="Page_34">[Pg 34]</a></span> is ever widely enough acquainted +with the animal world to classify all the specimens gathered on such +an expedition. In accordance with custom, Darwin began distributing +his collections among specialists. Each of these was to identify and +describe, to name, if necessary, the kind of material he knew best. +Among others, Darwin had a considerable collection of barnacles +gathered from boats and wharves in all parts of the world. As he could +find no one sufficiently acquainted with these creatures to classify +them he decided reluctantly to work them up himself. For about eight +years much of his spare time was given to this painfully exacting +work. He expresses himself as fearing it was a waste of time. Few +systematic workers will agree with him. He did his work so well that +it has been unnecessary for anyone to do it again. In addition it +gained him the esteem of a new circle of scientists and that a +decidedly exclusive circle.</p> + +<p>The publication of these books did much for Darwin. His narrative of +the voyage gained the good will of cultured England in general. The +book on coral reefs won the geologists. His "Manual of the +Cirrhipedia" (as the barnacle book was called) secured the attention +of systematic zoölogists. The time was not far distant when he would +need every aid possible toward gaining and keeping the regard<span class="pagenum"><a name="Page_35" id="Page_35">[Pg 35]</a></span> of men; +for he was to promulgate a theory that would arouse the bitterest +opposition and the keenest scorn.</p> + +<p>All the while Darwin was working on these books his mind was quietly +busying itself with what he called the species question. The more he +studied the material collected on his long tour, the more confident he +became that the animals of the present are the altered descendants of +the animals of the past. He tried patiently to work out every +conceivable hypothesis to see whether he could account for the +alteration. He felt quite sure animals changed, but how they changed, +and why, he could not for a long time conceive. He knew that gardeners +were constantly producing new varieties of plants, and that animals of +various breeds were clearly the descendants of other and familiar +varieties. Accordingly he began to study the methods of animal and +plant breeders, to visit their farms, to open correspondence with them +and read all their trade journals, to undertake experiments in the +breeding of plants. The longer he worked the more confident he became +of the reality of the change; but for a long time no glimmer of the +cause by which it could be brought about came to his mind. In 1838 he +came across a book by Malthus called "An Essay on Population," in +which the author shows that, whereas man increases by a geometric +ratio, he cannot hope to increase his food supply in more than an<span class="pagenum"><a name="Page_36" id="Page_36">[Pg 36]</a></span> +arithmetic ratio. That is, while the food might increase like the +series 2–4–6–8–10, the population would increase like the series +2–4–8–16–32. On this basis it is only a question of time when the +earth will be too full of people for it to be possible for the food to +sustain them. Malthus added many observations and suggestions, but +this is as much of the book as interests us in this connection. Here +was the idea that suggested to Darwin his agency for producing the +change of the animals of the past into those of the present.</p> + +<p>The number of animals of any particular species remains practically +the same. There may be a few more one year, and a few less another, +but on the average, year by year, the number of toads, the number of +blacksnakes, the number of field mice, remains sensibly the same. +Sometimes the rise of man brings an end to the wild population, and so +in the past animals have dropped out of the race. Yet in the long run +and for a considerable time the number of any species is constant. But +each animal produces offspring in quantities sufficient to far more +than replace himself as he dies out. In other words, animals increase +not by addition but by multiplication. Too many are born for all of +them to live. What becomes of the great mass of them? The answer is +they die; most of them die young. Only a few fortunate in<span class="pagenum"><a name="Page_37" id="Page_37">[Pg 37]</a></span>dividuals, +favored by being a little stronger, a little more cunning, a little +more attractively colored than their mates, survive to carry on the +race.</p> + +<p>The skillful gardener, looking over his flowers, finds a plant of more +than ordinary beauty and thrift of growth. When it comes to maturity +he keeps its seeds separate from those of the rest and next year +plants them by themselves. As they come up he weeds out all unthrifty +plants, only allowing the strongest to come to maturity. As they break +into bloom he plucks away all whose flowers do not come up to the high +standard he has set for himself. After a while he has but a few plants +left, but these are the thriftiest and bear the most beautiful +flowers. Again he allows these to mature and selects the seed of the +very finest. Next year the process is repeated. After a few +generations, usually three if the man is skillful enough, he has a +definite strain of flowers that will thereafter come true. This is the +process of artificial selection as carried on by man.</p> + +<p>Darwin saw that Nature is constantly carrying on a similar process. +She produces seeds enough on almost any plant to clothe the world in a +few years if all of them could fall into proper ground and thrive like +their parents. A friend of mine found a mullein stalk that bore more +than seven hundred seed pods and averaged more than nine hundred seeds +to the<span class="pagenum"><a name="Page_38" id="Page_38">[Pg 38]</a></span> pod, a total of more than six hundred and thirty thousand +seeds. If each of these could find lodgment on a plot eighteen inches +square, produce a similar number of seeds and plant them all, the +result would be overwhelming. The fourth generation would cover land +and sea, from pole to pole, one hundred layers deep. But there is no +such danger. Year by year the mulleins hold their own and no more. Any +particular field may have more or less, but in the long run the +average for a district is about the same. Some of the seeds are poor +and thin. These scarcely sprout. Others spring up into thin-skinned +plants, and the first frost nips them. Still others lack the woolly +coating in its finest abundance, and the browsing animals eat these. +Others lack power to put out a wide-ranging root supply and the first +drought kills these. Still others fail to send up a vigorous stem and +the passing animal knocks them over and they die. Of the few that are +still surviving, some produce such small and inconspicuous blossoms +that the insects scarcely see them, and they go unfertilized. In the +end only the aristocrats of the group are left, aristocrats in the +best sense of the word. These are strong, thrifty, and beautiful, and +are provided with every defense known to the mullein world. From these +the mulleins of the next generation will spring. Again Nature will +select the best of these, by a repetition<span class="pagenum"><a name="Page_39" id="Page_39">[Pg 39]</a></span> of the same process. Thus +year by year the stock is improved. Any new feature that is favorable +helps its possessor to survive, and, if happily mated, will show +itself after a while in the entire group. This, in brief, is the +underlying idea of Natural Selection, as Darwin conceived it.</p> + +<p>In 1842, at Lyell's suggestion, Darwin wrote a short sketch of his +ideas which he, two years later, expanded into a somewhat larger +account. The manuscript of these early views of the theory was +completely lost and has only been recovered within the last few years. +It was recently published under the editorship of Charles Darwin's +son, Francis. It is astonishing to see how clearly the first short +sketch states the underlying conception which all of Darwin's +subsequent work amplifies. Hooker was constantly urging Darwin to +write out his whole theory in the form of a book, and Darwin had begun +to do so in 1856.</p> + +<p>Meanwhile, down in the Moluccas, Alfred Russell Wallace had been lying +sick of a fever contracted during his exploring expedition in that +neighborhood. He had been studying the distribution of the animal life +of the Malay Archipelago. Overcome by sickness, as he lay in bed, he +began to think over a book which he had read not long before, "Malthus +on Population." Wallace had been pondering on the<span class="pagenum"><a name="Page_40" id="Page_40">[Pg 40]</a></span> question of the +origin of the animals of the Malay Archipelago. He had not the +faintest knowledge of what Darwin was doing, but was influenced, of +course, like Darwin, by what he read in Malthus. Interesting to +relate, he had come to exactly the same conclusions, writing his +opinions in the form of an essay. By the strangest sort of +coincidence, he sent this essay to Charles Darwin, asking him to read +it, and, if he thought it was not altogether too foolish, to send it +to Lyell for publication by the Linnæan Society. Darwin read with +utter astonishment this essay containing views so absolutely like +those that had come to him from his own long series of observations +and reflections. With uncommon magnanimity his first impulse was to +withhold his own publication entirely, but to this Lyell and Hooker +would not for a moment consent. They were determined that Darwin +should give them his long series of notebooks as evidence of the +independence of his work and that he present to the Linnæan Society, +simultaneously with Wallace's paper, one of his own upon the same +subject. In this manly form both essays were read at the next meeting +of the society. The joint papers provoked instant discussion and +prompt opposition. The world at large scarcely admitted a possible +doubt of the fixity of species. Men generally believed the idea to be +absolutely irreconcilable<span class="pagenum"><a name="Page_41" id="Page_41">[Pg 41]</a></span> with their religious faith. Any question of +the fact that the species of to-day exist practically as they had been +handed down to the earth in the beginning by the Creator himself +seemed to most men a direct blow at religion. At this time a very +large number of natural scientists were clergymen, hence the +opposition had abundant and influential support. The storm grew +fiercer and more widespread. The publication in 1859 of Darwin's great +book on "The Origin of Species by Means of Natural Selection or the +Preservation of Favored Races in the Struggle for Life" added fuel to +the flame.</p> + +<p>In 1860 the British Association met in Oxford, and Bishop Wilberforce, +the retiring president, in accordance with the custom of the society, +gave a summary of the advance of science, especially during the +preceding year. Everyone knew perfectly that the bishop would deal +with the species question, and that he would handle it severely. +Darwin was prevented by his usual ill health from being present at +this meeting, but Huxley was there to see that their side of the +question received proper attention. The bishop made a lengthy address, +in the major portion of which he brought forward entirely worthy +objections to Darwin's theories. Toward its close his feelings +overmastered him and he departed from his manuscript and unburdened +his mind. The lack of stenog<span class="pagenum"><a name="Page_42" id="Page_42">[Pg 42]</a></span>raphers in those days and the tenseness +of the moment, which made everyone forget to take down what was said, +make it impossible to tell exactly what happened. It seems that Bishop +Wilberforce, appealing to the prejudices of his audience, said, in +language that now seems ludicrous but then was terribly bitter: +"However, any of us might be willing to consider ourselves descended +from an ape upon his father's side, no one would so demean his +mother's memory as to imagine that she could possibly have shared in +this descent." Huxley, who had waited patiently for the close of the +bishop's address, saw immediately the fatal mistake. Turning to his +companion beside him, he said, "The Lord has delivered the Philistine +into my hands," and, rising, he hurled back at the bishop the +indignant reply, "I should far rather owe my origin to an ape than I +would owe it to a man who would use great gifts to obscure the truth." +The bishop had made the mistake, and the struggle was on. Year by year +it raged. One by one the scientists, first of England, and then of +Germany, took their stand by Darwin. Huxley in England and Haeckel in +Germany were the foremost advocates of the Darwinian idea. Long and +fiercely the battle raged; slowly and gradually men began to see that, +instead of undermining religion, the idea of evolution uplifted +creation and made it not a strange happening in the distant past, but +a<span class="pagenum"><a name="Page_43" id="Page_43">[Pg 43]</a></span> divine activity through all time. But the battle had by no means +subsided when one day came the sad news that Darwin's heart, so long +feeble, so serious a hindrance to his work, had beaten its last on +April 19, 1882.</p> + +<p>His own people wished to bury Darwin quietly at his home in Down, but +Darwin now belonged to the nation. A petition signed by many public +men was sent to the Dean of Westminster, asking that his body might be +granted burial in the Abbey. Probably no greater honor can come to man +to-day, and fortunately Dean Bradbury was broad-minded enough to +acquiesce. So it came to pass that the church that had so long +believed him her enemy, that had first so bitterly fought him, came at +length to see that he added a new dignity and worth to her faith, and +took him to her bosom. Darwin's body lies buried in the Abbey.</p> + +<p>In all the glorious company of immortal dead whose earthly frames are +gathered in England's great mausoleum, there is no other one who has +done so much to modify the mind of thinking man.</p> + + + +<div class="section_break"></div> +<p><span class="pagenum"><a name="Page_44" id="Page_44">[Pg 44]</a></span></p> +<h3>CHAPTER III</h3> + +<p class="chapter_subhead">The Underlying Idea</p> + + +<p>We have seen in the preceding chapters how the idea of evolution +worked its way through the minds of men. Man after man got a glimpse +of the idea, even among the ancient philosophers. But no one could +speak convincingly on the subject before modern times, when a wider +acquaintance with the animal world gave a body of facts on which it +was safe to base conclusions. Even then the idea eluded men, until +there came a worker trained by a long voyage around the world in which +he had nothing to do except to study nature. He finally gathered in +his mind material sufficient to convince himself not only of the truth +of evolution but of the process by which this evolution was brought +about. Every scientific principle is simple in its basal idea. In +actual life the action of the principle may be so bound up with others +as to need a skillful mind for its detection. But under all the +complexities and modifications, like a silver thread woven into a +cloth, runs the basal idea. Until a master has detected it the +presence of it may<span class="pagenum"><a name="Page_45" id="Page_45">[Pg 45]</a></span> be unsuspected. But once discovered and expounded, +thereafter anyone may follow out its workings. So it is with the +Darwinian idea of selection. It waited long for a discoverer, but, +once found, we cannot but wonder why men did not see it earlier, it is +so simple.</p> + +<p>Mr. Darwin's mind, while slow and cautious, had a wonderful +perseverance. When he had finished his work he had not only given a +clear account of the process of evolution, but he had foreseen almost +all the valid objections that were afterward to be brought against his +theory. Some of them he had explained quite fully; of others he +indicated a possible explanation; of still other questions he +confessed that as yet they were not plain. But the whole theory is so +simple in its fundamental ideas that it has completely revolutionized +the whole aspect of modern biology and, indeed, of modern thinking in +many lines.</p> + +<p>There are four underlying conceptions, each simple in itself, which +must be clearly perceived before one can understand Mr. Darwin's +theory of "Natural Selection." The first of these is known under the +name of Heredity. It is a matter of common observation that every +animal or plant produces offspring after its own kind. Under no +conditions would we expect a duck to lay an egg from which could hatch +anything but a duck. No Plymouth Rock chicken<span class="pagenum"><a name="Page_46" id="Page_46">[Pg 46]</a></span> mated with another of +her own kind will ever lay an egg that will produce a Rhode Island +Red. We may believe that the dog has descended from some form of wolf, +but it is not meant that at any particular time in the past any wolf +mated with a wolf ever produced pups that were anything but wolves.</p> + +<p>Why this should be so is one of the most profound problems of biology. +Nothing but the fact that the process has gone on under our eyes for +so long a time could blind us to its marvelous character. To open the +egg of a chicken and examine it by the most refined methods known to +science is to find in it absolutely nothing that could be by the +widest stretch of the imagination considered anything like a chicken. +The biologist who has examined such eggs before and knows them in all +stages of the process may recognize in an egg which had been incubated +for a short time something which his previous experience tells him +will become a chicken. But it has not the faintest resemblance to a +chicken until later in its development. In early spring one may gather +pond snails from any country stream and place them in an aquarium. The +change from the cold water on the outside to the warmer water of the +aquarium and the temperate climate of the room hastens the process +which in the stream would not take place until later. In a short time +one may find fastened to the glass side of<span class="pagenum"><a name="Page_47" id="Page_47">[Pg 47]</a></span> the aquarium the little +mass of transparent jelly which surrounds and protects the delicate +eggs of these creatures. Fastened as they are it is easy to direct a +magnifying glass so as to observe the change which goes on within +these transparent eggs. It is even possible to apply a microscope in +such a way as to watch the transformation under the low power of the +glass. At first the eggs are as clear as water, having at the center a +slightly yellowish spot. This central mass divides and subdivides +until the separated sections grow so small and numerous as to lose +individuality. Then the mass begins to press out here and dent in +there. After a little while a double line of fine, hairlike +projections runs around the creature. These hairs wave in such fashion +as to make the embryo snail revolve slowly in its egg. A little later +and swellings become more pronounced over the surface. One side +flattens; the rotary motion stops; eyes appear at the front of the +animal; a hump on the back begins to be covered with a shell, and the +little creatures, pushing from the jelly, start their life journey on +the side of the aquarium. Why did it happen? How did it happen? Here +we have seen creation at work. Here surely the hand of the Creator is +working in the only sense in which the Creator may be properly said to +have a hand. How the history of the substance out of which the egg was +produced provides<span class="pagenum"><a name="Page_48" id="Page_48">[Pg 48]</a></span> for the future development of that egg no man has +yet clearly said. This is not to say that we shall never know, still +less is it to say that this can never be known. Ralph Waldo Emerson +has said that there is no question propounded by the order of nature +which the order of nature will not at some time solve. If he is right, +and I believe he is, we shall at some time know how it is that this +egg produces this snail. But, as I said before, nothing but the +frequency with which the process goes on under our eyes could possibly +blind us to the marvel of it.</p> + +<p>The regularity with which each animal reproduces its kind is no more +surprising than the faithfulness of that reproduction. Some of our +birds have wonderful markings on their plumage. It is astonishing to +see with what fidelity the feather of a bird may reproduce the +corresponding feather of its parent. It will occur to everyone how, in +the human family to which he belongs, there is some little peculiarity +which, while not appearing in every member of the family, when it does +appear is remarkably uniform. It may be only the droop of an eyelid, +it may be a tendency to lift one side of the lip more than the other, +it may be the peculiar shape of a certain tooth in the set, and yet +when it appears it comes with astonishing similarity in all who +possess it. So much for the principle of Heredity.</p> + +<p><span class="pagenum"><a name="Page_49" id="Page_49">[Pg 49]</a></span>The second great underlying idea is known by the name of Variation. We +have just been dwelling on the regularity with which parents produce +offspring like themselves. We must now draw attention to the fact +that, while it is true animals must absolutely belong to the same +genus or species, even to the same variety, none the less no animal is +exactly like his parents. Furthermore, in a group of animals produced +at the same time from the same parent each one will have at least some +small point in which he differs from every other one in the group. Two +animals may look alike at first to the undiscerning eye, but a keen +analysis of the measurements of the various parts of their bodies will +show distinct differences. This is quite as true among lower animals. +A toad may lay a double string of four hundred eggs which may be +fertilized by the same male at the same time. These eggs may develop +into tadpoles in the same pool not over a foot square. Within a few +weeks these little toads may have gained their legs, lost their tails, +and all may have left the water and taken to the ground upon the same +day. Already the careful observer will notice differences among them. +Some are larger than others, having grown more rapidly even though +their surroundings were exactly the same; others are more skillful in +their peculiar method of throwing the tongue at an insect they wish to +catch.<span class="pagenum"><a name="Page_50" id="Page_50">[Pg 50]</a></span> Still others will be differently colored. They might be +arranged to show a considerable gradation between the lightest and the +darkest of the group, though there may not be anywhere in the row a +considerable gap. It is variation in animals of the same parentage and +same surroundings which in the mind of Mr. Darwin made evolution +possible. He always favored the idea that it was the continuous +accumulation of these small variations that finally produced the +profound changes which mark the new species. He admitted the +possibility of the occasional appearance of those more distinct leaps +in variation on which the present school of mutationists so strongly +insists; but he believed them to be less influential, in the general +trend of evolution, than the slower but much more frequent variations.</p> + +<p>One of the most complicated and perplexing problems in the biology of +to-day is the question of the origin of these variations. It is quite +as hard to understand as is the method by which animals produce their +own kind. No problem is being more earnestly studied. Suppositions we +have in considerable number, and two of these at least may reasonably +be mentioned. We will consider first the less certain theory. There is +nothing in the egg that in the remotest degree resembles its parent. +The old idea that every acorn had in it a miniature oak which only<span class="pagenum"><a name="Page_51" id="Page_51">[Pg 51]</a></span> +needed to unfold itself, or that the hen's egg had within it a +miniature chick which only needed the warming process in order to make +it evident, could not possibly survive the invention of the +microscope. We may not, and we certainly do not, know everything that +is in one of these eggs, but we do know most certainly that what is +there has no resemblance to what it will be in time. The biologist +finds in the nucleus or central core of every growing and reproducing +cell certain minute bodies which Weissmann believes do much to +determine the growth of the rest of the cell. He believes also that +there are many more such "determinants" than are necessary for the +reproduction of the cell. Each of these determinants may be fitted to +produce slightly different results, but what decides which of them +shall have its own way is quite uncertain. It may be that one +determinant happens to be more favorably placed than others in the +cell and that it has consequently secured more of the nourishment that +comes to the cell in the blood of its parent. If this is true it would +certainly be favored in the competition. We are becoming quite certain +that whatever variations arise really start in the egg. The simplest +conception as to the cause of variation would seem to be varied +experience. One man trains his brain, another his hand; and in each +case the organ so trained develops. But science is strongly of the<span class="pagenum"><a name="Page_52" id="Page_52">[Pg 52]</a></span> +mind that such influence does not reach the next generation.</p> + +<p>A musician may have taught his fingers to be nimble; may have given +them speed of motion and precision in their action. No child of his +born after he acquired this wonderful facility of execution is any +more likely to be a skilled musician than a child born before he had +ever practiced enough to be anything more than a crude performer. +Science is nearly certain that his children are just as likely to be +talented along musical lines if he himself never had become a +musician, simply because he had it in him to be a musician. In other +words, they may inherit the talent which he developed, but they +inherited it not because he developed it, but because it was in him to +be developed. This is in accordance with the famous principle that +there is no inheritance of acquired characters. We shall touch this +question a little more fully in a later chapter, in speaking of the +development of the evolution theory since Darwin's time.</p> + +<p>If we are right in this matter, and we certainly are nearly right, +variation must take place for the most part in the germ. These +variations may not show until the animal has grown up, but they must +have taken place among the determinants in the germ cell or they would +not reappear in subsequent generations.</p> + +<p><span class="pagenum"><a name="Page_53" id="Page_53">[Pg 53]</a></span>There is another process by which new variations may arise and which +is more easily understood. It is the method of double parentage. The +Barred Plymouth Rock chicken had its origin in such a double ancestry. +The one parent was a Black Java whose color has disappeared entirely +in the cross, but whose single comb with its few large points comes +out clearly in the newly produced fowl. The other parent was a Barred +Dominique. It is to this parent that the Plymouth Rock owes the +interesting cross markings on its feathers. The comb on the head of +the Barred Dominique is of the type known as the rose-comb, having +many rows of slight projections. This has completely disappeared from +the Plymouth Rock fowls. I am told that the skilled chicken fancier +can tell, concerning many points in this fowl, to which of the crossed +ancestors each quality is due. To a certain extent it is undoubtedly +true that here we have the secret of the origin of many of those +interesting people whom we are pleased to call geniuses. They may not +possess any qualities not clearly discernible in various of their near +ancestors, but in them we find what we, for the lack of a better +understanding, call chance combination in one individual of the finer +qualities of many ancestors, and this individual is so placed in life +as to have these qualities developed and strengthened.</p> + +<p><span class="pagenum"><a name="Page_54" id="Page_54">[Pg 54]</a></span>Charles Darwin, humanly speaking, may be accounted for as the happy +combination of a double heredity and a favorable environment. He +inherited the scientific inclinations of his grandfather, Erasmus +Darwin, and the patient, sturdy honesty of his other grandfather, +Josiah Wedgwood. These developed under the stimulus of the long +five-year voyage, face to face with the world of nature. This happy +complex produced the master biologist. To believe that he came about +purely by chance requires a great stretch of the imagination. "There's +a divinity that shapes our ends."</p> + +<p>We have endeavored to make clear two of the basal ideas underlying +evolution. One of these is responsible for the continued production of +animals or plants of the same kind, preventing the world from becoming +a wild kaleidoscopic and fantastic dream. Heredity is the conservative +force of nature. The other idea underlies the development of new +departures which keep the world from being a dull, dead, unending +repetition of the same monotonous material. Variation is the +progressive tendency in nature.</p> + +<p>The third basal idea is that of Multiplication. Animals and plants +multiply; they do not simply increase, they increase in a geometrical +ratio. Anyone who has worked out one of these geometrical ratios knows +how wondrously they mount up. There is an old fa<span class="pagenum"><a name="Page_55" id="Page_55">[Pg 55]</a></span>miliar story of the +blacksmith who asked the price at which the stranger would sell the +horse he was shoeing. The owner of the horse replied that, if the +blacksmith would give him one penny for the first nail he drove into +the shoe, two for the second, four for the third, and so on, he might +have the horse. No hundred horses in the world taken together have +ever brought such a price as the blacksmith would have had to pay for +the animal on which he was working. This is no circumstance to the +awful story of what would happen to the earth if any animal could +multiply unrestricted. The usual number of eggs laid by a mother robin +for a single brood is four, and she may produce two broods in one +season. This would mean that the original pair had produced eight +offspring, four times their own number. If we can imagine these mating +the next year and producing their kind in the same proportion; and, if +we further suppose that each robin needs a space one hundred feet +square from which to gather his food, we realize the astonishing fact +that in fifteen years every patch one hundred feet square in +Pennsylvania and New York would each have its resident robin, while +the following season would find a robin on every similar patch from +Maine to the Carolinas. Of course this could never happen, this is +simply what would happen if all the robins could grow to maturity and +reproduce at the<span class="pagenum"><a name="Page_56" id="Page_56">[Pg 56]</a></span> normal ratio. But the robin is a comparatively slow +producer.</p> + +<p>Our turtles are more prolific. Twenty eggs would probably not be an +unusual number. If we could imagine a turtle to live in the sea and to +produce at this rate; and, if each turtle should need as much room +each way as the robin, and a depth of water equal to its width, before +the robins had spread over New York and Pennsylvania the turtles would +have filled all the seas of the globe. Frogs are even more remarkable +in this respect. Two hundred eggs is not an uncommon number. If each +frog required a space twenty-five feet square on which to subsist, the +entire earth would be more than covered with them within six years. It +is ludicrous to think of such numbers, especially when we realize the +hundreds of thousands of kinds of animals there are in the world, each +of which is also multiplying, and it becomes evident at once that only +an infinitely small proportion of all these creatures can possibly +survive. This, then, is multiplication.</p> + +<p>Here comes into play the fourth basal idea in Mr. Darwin's +explanation. This is the part of Selection. When man produces new +varieties of animals he does it by picking out from his flocks or his +herds such as conform most nearly to his idea of what is desirable. +These he mates, and from their progeny he selects<span class="pagenum"><a name="Page_57" id="Page_57">[Pg 57]</a></span> the ones that suit +him best. Generation by generation he gets his domesticated animals to +conform more nearly to the standard of his desires. Natural selection +works in exactly similar fashion. Of all the eggs that are produced by +the animals at large in nature an overwhelming proportion never +develop at all. They dry up, are eaten by their enemies, find no +suitable place or time for development and decay, or are overtaken by +some other calamity. Of the animals which emerge from the remainder an +overwhelming majority come to an untimely end within the first few +days of life. Each has countless enemies which prey upon him, and +these have scarcely devoured him before they themselves become the +prey of some stronger creature. Until Mr. Darwin gave us his elemental +idea it was taken for granted that it was a matter of pure accident +which survived and which yielded in the struggle and cares of life. It +was Darwin who showed us that in this tremendous struggle against +those of his own kind in the search for the same food, against the +elements, in securing a mate, any animals possessing a superiority, +however slight, must have some little advantage in the battle. +Certainly, where so many must utterly fail, only those could possibly +succeed who were well fitted to the circumstances in which they must +live. We used to think animals were destroyed by the "accidents" of<span class="pagenum"><a name="Page_58" id="Page_58">[Pg 58]</a></span> +life and no one could foretell accidents. Mr. Darwin made clear that +it was not a question of chance. That which might happen to any +individual animal might be what we, not knowing the process, called +accident, and yet there could be no possible doubt that those who +succeeded were better fitted to battle with life than those who +failed, and that their success was due primarily to their being thus +advantaged. Consequently, if generation by generation the so-called +accidents of life are constantly eliminating the unfit in overwhelming +proportions, not only must the positively unfit disappear, but even +the less fit. The more keen the struggle, the fewer could survive and +the fitter they must be to survive at all. This is Selection. These, +then, are Darwin's four great factors of evolution: Heredity, +Variation, Multiplication, Selection.</p> + +<p>From these it results that the animals and plants naturally become +better adapted to the situation in which they are placed. When, as is +constantly happening through the history of the earth, a change occurs +in the physical geography of any region, when a plain is lifted to be +a plateau, or a mountain chain is submerged until it becomes a row of +small islands, this alteration will produce uncommon hardships among +animals, even though they were well fitted to the old conditions. Any +animal or any species of<span class="pagenum"><a name="Page_59" id="Page_59">[Pg 59]</a></span> animals which meets such a calamity has +before it only three possible outcomes of the struggle. First it may +be plastic enough and it may vary enough in the right direction to +adjust itself to the changed conditions. In this case it and a favored +few like it will occupy the altered territory. The second possibility +is that it may migrate while the actual change is going on, thus +remaining in the sort of situation suited to it and its kind. The +third possibility is the one which overtakes a great majority of +animals—they die. Even the entire line dies out, and the strata of +the rocks are filled with the bones, shells, and teeth of such as have +met this fate. They have become extinct.</p> + +<p>Thus far in this chapter we have been considering the influences under +which it is conceivable that animals should advance. There is no +question whatever that there are too many animals born, nor is there +any possible question that a very large proportion of them must +certainly die. There is equally no doubt that every animal produces +after its own kind, and that its offspring, while they resemble it +closely, still vary a little from it and from each other. This fact is +perfectly plain to the most superficial observer who thinks on the +matter at all. It is not so plain, nor is it easily demonstrated, that +all of these acting together do surely, even if slowly, alter the form +and<span class="pagenum"><a name="Page_60" id="Page_60">[Pg 60]</a></span> behavior of the animal world. It is difficult to prove that there +is going on under our eyes a steady and real improvement in the +adaptation of the animals and plants around us to the situation in +which they are placed. As far back as man's memory runs they seem to +have been about what they now are; as far even as man's historical +record runs they seem to have suffered no great alteration. The +Egyptian of the old tombs is much like the Egyptian of the same rank +to-day. The African of the tombs has the African features of to-day. +Under such circumstances it is hard to prove that there is a steady +and undoubted advance. For the most part the balance of the animal +world is fairly even, and any species does not ordinarily change +rapidly enough or migrate widely enough to show us its new features. +It is difficult to see the struggle which we are so sure is going on. +The life of animals is so hidden in many of its details that their +joys and sorrows, if such we may call them, scarcely fall under our +observation. Now and then an opportunity comes to see the process of +adaptation work itself out. The struggle for existence begins anew and +is carried on with special vigor, with victory, temporary or +permanent, to one of the participants in the struggle.</p> + +<p>The opportunity to observe such a change is presented in the United +States by the introduction of the<span class="pagenum"><a name="Page_61" id="Page_61">[Pg 61]</a></span> so-called English sparrow. This +little creature, received at first with such joy, soon became the +object of an almost bitter hatred on the part of very many people. +This is really due to the fact that this bird is one of nature's +darlings and thoroughly succeeds where it has an even chance.</p> + +<p>The number of birds of any particular species which a region will +support seems to be fairly definite. If a species is especially +protected until it becomes unusually abundant, the removal of the +protection commonly brings it down promptly to its original numbers. +On the other hand, an accident of severe character or a special +persecution may much diminish the number of the species, and still it +will, within a comparatively few years, return to its previous +abundance.</p> + +<p>The inhabitants of Florida who own orange groves will never forget the +winter of '94–5. A bitter cold wave swept along the coast and killed +such large numbers of orange trees as almost to cut Florida out of the +orange market and to open the gate to California, who was eagerly +offering her fruit. This same frost caught the migrating blue birds +and killed them by the thousands. When spring came bird-lovers +throughout the eastern United States found an astonishing scarcity of +these favorites. It was feared that with numbers so small they could +not possibly compete with their enemies and with whatever untoward +circum<span class="pagenum"><a name="Page_62" id="Page_62">[Pg 62]</a></span>stances should be their lot. But there is room in this +environment for a definite number of bluebirds. When this number was +suddenly reduced the chances to make a bluebird's living were so +wondrously multiplied that young bluebirds had such an opportunity in +life as their fellows had not had for many long years. Accordingly +they thrived as never before, and, of their progeny, a larger +proportion lived to the following year. It was only a few years before +the number of bluebirds had risen. Now we probably have as many as we +have had for a long time past. I cite this simply to show that a +region can support a certain number of animals of any one particular +kind, and that the animal is likely to multiply, if given a fair +chance, until it has reached such proportions. Now to my story of the +rapid development of a newcomer.</p> + +<p>In the year 1850 a resident of Brooklyn came home from a trip to +Europe. He was a lover of birds, and while in Europe had been +particularly attracted, no one now knows quite why, to the common +House Sparrow, as it should be called. It is no more abundant in +England than in many parts of the continent of Europe. A name that has +been used for a long time is very hard to cast aside, and we shall +probably continue to mistakenly call him the English Sparrow to the +end. Our Brooklyn traveler brought home with him from Europe eight of +these interesting little birds<span class="pagenum"><a name="Page_63" id="Page_63">[Pg 63]</a></span> and succeeded in inducing his +colleagues in a scientific society to share his interest in them. Not +wishing to commit the newcomers suddenly to the rigors of the American +winter, these men built a large cage for the sparrows, meaning to set +them free in the spring. For some reason or other when the winter was +over the birds were all dead, and this first attempt to introduce the +sparrow into America failed entirely. The little bird had won so many +friends that his success was now sure. Finding a favorable +opportunity, these Brooklyn men dispatched an order to a man in +Europe, asking him to supply them with one hundred English sparrows. +The consignment came in good shape and the birds were liberated on the +edge of Brooklyn. This was the first of a number of introductions. A +little later New York City sent for two hundred and twenty of these +interesting creatures and turned them loose in her parks, while +Rochester, with what was then considered great public spirit, +purchased one hundred for herself. But the most progressive city in +this respect was Philadelphia. She had long been troubled with the +spanworm on her trees. This detestable larva had the unpleasant +fashion of lowering itself by a long silken thread from the shade +trees then so abundant in that beautiful city. The spanworms traveling +around over the clothing of the passersby were so objectionable to +everybody that<span class="pagenum"><a name="Page_64" id="Page_64">[Pg 64]</a></span> it was with greatest delight that Philadelphia heard +of the new birds which ate the pest. One wonders why some +ornithologist did not look at the bird long enough to see that it had +the sort of a bill characteristic of birds that eat seeds. It is true +that most birds feed their young on insects, hence there is a time +when any bird is apt to be insectivorous. But the structure of the +sparrow's bill, like that of all finches, should have warned these +bird-lovers that the sparrow was not to be depended upon to earn his +living by catching worms. It is easy, however, to be wise after the +event. Philadelphia believed she was engaging in a particularly +advanced movement when she imported from England one thousand English +sparrows, nearly as many as were liberated by all other cities +together. These birds were turned loose among the shady streets and +wide spreading parks of the City of Brotherly Love.</p> + +<p>It is a serious matter lightly to disturb the balance of nature by the +introduction of a new species. It is true that the sparrow did eat +some spanworms and for a while enthusiastic bird-lovers hoped that +here was the solution of the difficulty. Philadelphians will also +remember that, with the spanworm removed from competition, the tussock +moth, whose caterpillar carries on his back a series of yellow, red, +and black paint brushes, at once become the permanent parasite<span class="pagenum"><a name="Page_65" id="Page_65">[Pg 65]</a></span> of the +long-suffering shade trees. This caterpillar is covered with bristling +hairs, very closely set. Almost any bird objects to hair in his +victuals; and this particular larva has hair more than ordinarily +objectionable, for it irritates wherever it pricks the sensitive skin. +This coating seems to protect the caterpillar from the sparrow, with +the result that Philadelphia's trees were soon nearly defoliated by +this comparatively new pest, worse than the spanworm. With the paving +of the city's highways and the consequent shutting off of the air from +the roots, the trees have largely disappeared from the streets of +Philadelphia. With them have gone a fair portion of the tussock worms, +but the sparrow holds his own. Here is a new bird in the field, and +the struggle for existence on the part of every other kind of bird is +now more complicated and severe. The sparrow can live where the rest +of the birds have no possible chance. He throve so well in this +country that by 1875 he had spread over five hundred square miles in +the neighborhood of our larger Eastern cities. Thus far almost +everybody was pleased with the new introduction. Within the next five +years he had spread over more than fifteen thousand square miles, and +wise men were beginning to feel doubtful of the virtues of their +aforetime friend. When by 1885 more than five hundred thousand square +miles had been occupied by the enterpris<span class="pagenum"><a name="Page_66" id="Page_66">[Pg 66]</a></span>ing little fellow, there +remained no longer a doubt in the minds of most people that the +sparrow was an unmitigated nuisance and great fears were entertained +that he had multiplied to such an extent as to be a serious menace. +Here, then, is a modern instance under our own eyes of a victory in +the struggle. If the sparrow has multiplied rapidly, while all the +other birds have either only held their own or even have diminished in +numbers, it is quite evident he must be better fitted to the +conditions than they are. What are his fit points? Why does he succeed +while others fail? The thoughtful bird-lover will have little trouble +in understanding at least some of his victory-winning characteristics. +How did he come to be almost the only bird who can live in large +numbers in our great cities, without losing his ability to get along +in less crowded situations?</p> + +<p>In the first place this interesting bird is a clannish fellow. He has +lost the ordinary sparrow habit and has come to like to live in +crowded groups. Seclusion is not at all to his taste, and if there are +only a few sparrows in the neighborhood those few will most certainly +be found living near each other. One of the early adaptations of the +sparrow to his city surroundings was the ability to find for himself a +considerable proportion of his food in the undigested seed that could +be picked up from the droppings of the horses.<span class="pagenum"><a name="Page_67" id="Page_67">[Pg 67]</a></span> This naturally led the +surplus sparrows out through the many thoroughfares leading from any +large city. Where horses went sparrows could follow. Accordingly along +the great lines of travel this bird found the simple path by which he +could enter new territory. Meanwhile box-cars came into our large +cities with freight. Sometimes they had carried grain, sometimes +cattle. In either case it was not unlikely that a certain amount of +grain should be found scattered over the floor of such cars. The +sparrow visited these cars for the grain, and it must have been no +infrequent accident that a door should be shut upon a group of +sparrows, especially in inclement weather, when they were apt to be +huddled in a dark corner of the car. These prisoners would be carried +to the destination of the car and there liberated, thus producing a +new center of what we are now inclined to call infestation. By such +means the English sparrow has spread over much the larger portion of +the American continent. Few birds are bold enough to visit a railroad +car. Of the few who might be tempted, most are timid enough to fly on +the first approach of man. Hence they fail to gain this chance of +spreading. They must remain in the old crowded home. Meanwhile the +sparrow, thus transported, finds a new home with fewer or no sparrows. +The struggle is less keen. More of his kind can live. His boldness<span class="pagenum"><a name="Page_68" id="Page_68">[Pg 68]</a></span> +has been here a fit quality and has helped him in the race.</p> + +<p>Man is only slowly coming to be a city-dwelling animal. Although it is +a voluntary process with him, he still usually visits the country with +much enjoyment. He has not as yet learned to adapt himself thoroughly +to the city, for somehow city life kills him. Families that move into +the city gradually have a smaller number of children in each +generation until shortly the family is wiped out. The population of +the city must constantly be replenished from the country. But the +English sparrow is more adaptable than are the people. He has made +himself at home in the heart of the biggest city. The Wall Street +canyon is not deep enough, nor contracted enough, nor free enough of +food to blot out the life of the English sparrow. At the heart of the +deepest gully among the skyscrapers of our biggest cities we find this +little bird hopping between the horses' feet, darting out from under +the wheel of the push-cart, fluttering only a few yards to a place of +safety, to return at once to his scanty meal upon the pavement as soon +as opportunity offers. He is a typical city dweller and has learned to +thrive there. Again in this matter he has distanced other birds to +whom the city is more deadly than it is to people.</p> + +<p>Another very important element in his fitness for<span class="pagenum"><a name="Page_69" id="Page_69">[Pg 69]</a></span> the struggle of +life lies in the fact that he is unafraid of man. He is wary of man; +by which I mean he will quickly fly up from in front of man's feet. It +is exceedingly difficult to catch a sparrow in one's hand. It is far +easier to lure a pigeon within reach. But the sparrow, when escaping +your hands, comes to rest but a slight distance away, only to elude +you quite as successfully if you try again. If the sparrow is let +severely alone he becomes more and more familiar with men, flies less +promptly, and goes a shorter distance, but any attempt to trap him +renders him shy more quickly than almost any other bird we have. He +soon learns to avoid a trap in which his companions have come to +grief. Those who would poison or trap sparrows must change constantly +the base of their operations. This fearlessness of man is a valuable +asset to the bird, for it is an important defense against other foes.</p> + +<p>The most serious enemy the birds at large have, after man himself, is +the bird of prey. Hawks and owls capture a large quantity of our +smaller birds. Now the hawks and owls are for the most part shy of +man. They have gotten a bad reputation, especially if they are of any +size, because of their more or less pronounced proclivities for +seizing our domestic poultry, and consequently many people will fire +upon a hawk or an owl who would probably fire upon<span class="pagenum"><a name="Page_70" id="Page_70">[Pg 70]</a></span> no other bird. By +living close to man the sparrow is largely saved from the danger of +capture by these carnivorous creatures, and this is the first and a +very important element of the advantage to the sparrow of living near +man. But there is the additional advantage that man scatters about +him, in one way or another, a very considerable amount of waste food. +I have suggested that the seeds in the droppings of the horse form a +large proportion of the sparrow's food, and horses are to be found +only with men. In the neighborhood of man's home, unless he has become +sanitary to a degree which has only been attained in recent years, +there is usually more or less garbage, kitchen offal of one sort or +another. To this the sparrow has easy access and from it he makes many +a meal. But this fearlessness of man gives him still another advantage +which his competitors fear to use, it provides him with nesting sites.</p> + +<p>Man has the faculty of putting up ornamental trimmings on his house, +and there is no spot the sparrow chooses more willingly in which to +build his nest than the ornamental quirks and cornices of man's +architecture. A Corinthian column with comely leaves in its capital +seems especially designed for the comfort of the sparrow, and his +distinctly untidy nest is the familiar disfigurement of almost every +ornate public building. These are the advantages which come to<span class="pagenum"><a name="Page_71" id="Page_71">[Pg 71]</a></span> the +sparrow from his willingness to associate with man, and there are +comparatively few birds with whom he must share them. Few birds select +the immediate neighborhood of man's home for their nests. They may +live in the neighboring trees, they may haunt his orchard, but his +house, for the most part, they decline to frequent.</p> + +<p>Still another quality which makes for success in this buccaneer is the +willingness with which he will vary his food as occasion requires. It +is a not infrequent characteristic of the bird family that each +species should have its own rather restricted diet. Birds are quite +particular eaters, and many of them will come well nigh to starvation +before they will use unaccustomed food. The sparrow, on the contrary, +like man, eats almost anything he comes across that could reasonably +be considered edible. He belongs to a group of birds which are +structurally adapted to cracking the hard coats of seeds. This group +of birds known as the finches is provided with the sort of bill +familiar in the ordinary canary bird. It is short, heavy at the base, +comes quickly to a point, and is firm and strong. With it the bird +readily breaks through the hard outer coat of most seeds and feeds +upon the rich cotyledons that are enclosed within. Nowhere in its +entire structure does the plant crowd so much nourishment in so little +space as it does in the seeds. It is not by chance<span class="pagenum"><a name="Page_72" id="Page_72">[Pg 72]</a></span> that the great +human food is grain. The sparrow belongs to the one bird group that +makes a specialty of such seeds.</p> + +<p>Most of the English sparrow's cousins in this finch group confine +themselves rather rigidly to this diet. Here the variability of the +sparrow again gives him the advantage. He may have the family fondness +for seeds, but in their absence he can be content with almost anything +edible. In the early springtime, when the seeds of last year are gone +and those of the new year have not yet been produced, the sparrow is +not averse to eating young buds from the trees. At this time he is not +unlikely to eat our sprouting lettuce and peas. It is easy to be +severe on him in this matter; but for a creature like man, who has the +same tastes, who eats the enormous buds of the cabbage, the +cauliflower, and the brussels sprouts, or the more tender buds which +he calls heads of lettuce, it seems particularly inappropriate that he +should throw stones at this little creature whose tastes are so +similar to his own.</p> + +<p>While seeds are more suitable for an elder bird they are altogether +too indigestible to be the food of nestlings. So when the sparrow +finds its nest full we know he must sally forth in search of +nourishment more simple of digestion. Now for a few weeks he searches +assiduously, catching insects and caterpillars<span class="pagenum"><a name="Page_73" id="Page_73">[Pg 73]</a></span> of various kinds, and +feeds them to his young. This taste passes as his children grow older, +especially as shortly the seeds begin to ripen. Now is the time for +the sparrow to fatten. Now he is eating the food for which he was +really built. By the time the wheat is ripe there are sparrows enough +about to form quite a flock, and when these settle down in a wheat, +rye, or oats field and feed upon the grain, meanwhile shaking out upon +the ground perhaps as much as they eat, the farmer begins to realize +that the sparrow is not his friend.</p> + +<p>When winter comes the struggle for existence among the birds is +intensified, and comparatively few of them dare face it. Most of our +birds betake themselves to less rigorous quarters, leaving to the +sparrow a comparatively small number of competitors for the diminished +supply of food. As long as the snow is off the ground the sparrows can +find sufficient sustenance. They gather themselves into groups and +sally out from the city into the open country. The immediate result is +that great quantities of weed seeds are seized upon by the English +sparrow, as, indeed, by every other finch which is with us in winter. +Perhaps we have not given the little fellow credit for the good he +does at this particular time, for the rest of the account truly does +not help him in our esteem.</p> + +<p>There is a further direct advantage in the sparrow's<span class="pagenum"><a name="Page_74" id="Page_74">[Pg 74]</a></span> sociability. One +robin may nest in the vines about your porch. If there were room for a +dozen, scarcely more than one would be likely to use it, because he +would drive away any other robin who attempted to share the +neighborhood with him. To the sparrow company is always in order. +While he may quarrel from morning until night with his fellow, it is a +sociable quarrel and neither would willingly forgo it. This union is +strength among birds, as with man. Every animal is safer from his +enemies when he can have the constant presence of others of his own +kind. The deer that stays in the herd is safer from the wolves. It is +only when the latter succeed in cutting out some weaker or less +sagacious animal that these carnivorous creatures succeed in tearing +down their prey. I think the superiority of the sparrow over most of +our common birds, when considered as a city dweller, is scarcely +understood. Because he had won in the race with other birds is no +necessary indication that he warred directly against them. Bird-men +often attribute to him a quarrelsome disposition, as if he actually +drove other birds away. It almost seems like animosity against the +sparrow to speak of him as attacking blackbirds and crows. It is a +cowardly crow who can be driven away by a sparrow, and if the two +cannot live together it seems to me certainly to the discredit of the +crow and not of the sparrow. I be<span class="pagenum"><a name="Page_75" id="Page_75">[Pg 75]</a></span>lieve the truth to be that, while +the sparrow is undoubtedly a quarrelsome fellow, his bickerings are +his form of social converse with those of his own kind. A quarrel +among themselves seems not to indicate animosity, but would appear to +be the sparrow's idea of conviviality. It rarely leads to serious +results. I have never seen a male sparrow trounce any other bird with +half the vigor that I have occasionally seen the mother sparrow evince +when she caught her male companion by the feathers of his head, hung +him over the side of the limb, and vigorously and thoroughly shook him +until he desisted from his annoying and possibly insulting attentions. +The truth of the matter is that a colony of these little birds, with +their continual social chatter, including their quarrels, makes such a +continuous noise that the ordinary bird, which is generally of rather +quiet disposition, is too much annoyed by the unending nuisance to +find the neighborhood at all to his taste. Where a large number of +sparrows have gathered together the conditions are such as would give +a robin or a bluebird nervous prostration, and his only recourse is to +depart to a neighborhood where there is more peace and quiet. But our +English sparrow is not only better fitted for the struggle than the +robins and bluebirds, the orioles and the wrens. He has one important +advantage over even his own sparrow cousins. The males are +handsome—much<span class="pagenum"><a name="Page_76" id="Page_76">[Pg 76]</a></span> more so than the females or than their sparrow cousins +in general.</p> + +<p>In the song sparrow, field sparrow, chipping sparrow, and the fox +sparrow the male and female are very nearly alike in color. It often +becomes necessary for the bird-man to examine the internal organs of +the bird he is stuffing before he can certainly decide its sex. But +there is no difficulty whatever in telling the male from the female of +the English sparrow. The male is far the more ornate bird. His back is +striped with a richer brown; his head has two splendid dashes of +chestnut over the eyes; his throat and breast are splashed with red +and lustrous black; his bill is a clear fine black. Altogether the +bird is strikingly colored for a sparrow, and this characteristic is +the more remarkable when we see how quiet and somber is his more +modest mate. This brilliancy of male plumage in the presence of the +somber color of his mate would seem to indicate that the English +sparrow is eye-minded rather than ear-minded. It is true among human +beings that most of them are eye-minded. That is to say, they notice +things with their eyes chiefly. Memories they have are memories of +things seen; recollections of their friends bring up the appearance of +their friends. Their language is full of metaphors which imply form +and shape. But occasionally we come across an ear-minded person.<span class="pagenum"><a name="Page_77" id="Page_77">[Pg 77]</a></span> He +remembers voices quite as well as he remembers faces. To him music is +an unending delight, and painting and sculpture fall into a distinctly +secondary place. This is ear-mindedness. Now, most of the sparrows +seem to be ear-minded, at least as far as their recognition of their +mates are concerned. In this group beauty of song is developed many +times oftener than is especial ornateness of plumage. The bird-lover +who is himself keen of ear is never tired of listening, when in the +field, for the two low notes with which the vesper sparrow introduces +a song, the rest of which is not at all unlike the one of his +song-sparrow cousin. The field sparrow begins more like the song +sparrow, but ends with an often repeated note, which not a little +resembles in general character the somewhat more monotonous song of +the grasshopper sparrow or of the chippy. In comparison with these +melodious birds the English sparrow makes no showing whatever. His +voice is harsh and querulous, although very occasionally it is +possible for the bird-lover to detect a note or two which would +indicate that, if he were properly educated, his voice might amount to +something. He wins his wife not by his pleasant voice, but by his +attractive appearance and his winning ways. We have every right to +infer from the character of its fellow birds of the sparrow family +that once the female and male sparrow were<span class="pagenum"><a name="Page_78" id="Page_78">[Pg 78]</a></span> colored about alike. But +Madam English Sparrow was apparently eye-minded rather than +ear-minded. Whatever pleasant voice a suitor might have seems to have +been to her without attraction, and there was nothing to encourage him +in developing it, nor was she likely to mate with him for it and +transmit it to her male children. On the other hand, let a suitor +appear in whom a more brilliant coloring proclaimed his superior +vigor, and this seems to catch her eye at once. The less accomplished +rival in the tournament of love seems to have been already forgotten. +To their children these successful characteristics were naturally +handed on and led to equal success on their part. If any of these +children possessed this badge of honor in a more than ordinary degree, +he was the more likely to win a mate and thus again the opportunity of +passing on to his offspring his own distinct advantage. Generation by +generation the males have become more beautiful and the females more +discriminating. That the bird is either instinctively or actually +conscious of this advantage would appear from the constant fluffing of +his feathers and spreading of his highly colored wings with which he +evinces his admiration for his ladylove. Even the most hardened +dweller in the city can scarcely have failed to see the sparrow spread +his wings, fluff his feathers, and sink close to the ground, twirling +and gyrating about the<span class="pagenum"><a name="Page_79" id="Page_79">[Pg 79]</a></span> object of his affection. It must give him a +shock to see how often she proves temporarily or hypocritically +indifferent to the demonstrative proceedings. Indeed they may +terminate in a thorough trouncing of the male on the part of the lady +of his affections. Now this preference for color over song must have +evidently evolved in connection with the development of social habits +in the English sparrows. His cousins of the fields, our native +sparrows, are much less social, much less likely to be met with in +flocks. To birds who scatter more, beautiful song is a great +advantage. It can be heard at a long distance. But when birds flock +together a much better advantage is that of beautiful clothing, added +to alluring ways.</p> + +<p>But we have not nearly exhausted the catalogue of the traits belonging +to our little friend which give him the advantage over other birds in +the struggle for life. His ability to remain with us in winter when +most birds are gone stands him in good stead.</p> + +<p>It is readily observed by one who pays the least attention to outdoor +life that winter finds us with comparatively few birds. North of +Maryland and the Ohio River the robin is practically absent in the +winter, except in much diminished numbers close to the border. The +bluebird is similarly absent; the great flocks of blackbirds are gone; +the bobolink is missing entirely; the thrush and the catbird have all +left; the<span class="pagenum"><a name="Page_80" id="Page_80">[Pg 80]</a></span> flicker and red-headed woodpecker are also spending their +winter in the South. The great mass of our bird population has left us +until warmer weather shall bring back to us once more our feathered +friends. It is true that we are south to the snowbirds or juncos, and +their little slate-colored bodies, with their light breasts and their +white on each side of the tail, make our bare hedge rows brighter by +their presence. A few of our birds like the song sparrow and the +cardinal are hidden away in the thicket, and have not all joined their +comrades in the south.</p> + +<p>The English sparrow was once probably quite as migratory as any of the +rest of these, but a great change has come over his habits. With his +newly acquired fondness for the haunts of men he has suffered a change +in this respect also. Whatever may have been his reason for migrating, +it no longer holds. He now finds himself quite able to stand the cold +of winter. Accordingly he never leaves us, except very temporarily. +When the migrating season comes the sparrows of the neighborhood are +very likely to gather themselves together in a single group and take +to the neighboring country. I believe this flocking on their part at +this time of the year is a remnant of the old migratory habit. Until +snow covers the ground the sparrow is not likely to be seen again in +such numbers in the city. The advantage the sparrow gains<span class="pagenum"><a name="Page_81" id="Page_81">[Pg 81]</a></span> over his +competitors by not going south does not appear during winter. When +spring comes, however, his gain is evident. He has his choice of all +the nesting sites in the region. When the migratory birds return every +first-class place is filled by a sparrow's nest. Nothing but second +choice situations remain, and with these the late comers must be +content. When we consider how much the safety of the next generation +depends upon the security of the young while helpless in the nest, we +appreciate what the English sparrow has gained by staying throughout +the year. Often while the season is so inclement that it would seem +there is still danger of frost, the sparrow builds her nest. All sorts +of places are open to her choice. She will find a protected corner +under a roof, above a spout, in the corner of the porch, behind an +open shutter, in the vines against the side of the house, on top of an +old robin's nest in the tree, in the bird boxes which have been put up +for more desirable creatures; anywhere and everywhere this industrious +little mother is liable to build her nest. Her husband will help her +more or less in the task, often bringing material and helping to place +it in the negligent pile of which their nest is composed. But he does +a good deal more fussing and cheering up than he does actual work, and +she seems to depend much upon his cheerful presence for her happiness. +It is hard to discourage Madam Sparrow<span class="pagenum"><a name="Page_82" id="Page_82">[Pg 82]</a></span> when once she has set her mind +on home-making. A bird-lover, some time since, reported how a pair of +sparrows had started to build a nest upon his lawn. He, wishing to +interfere with the process, took a small rifle and shot the male bird. +Within twenty minutes the female, who had scouted round the +neighborhood, returned with another mate and resumed her nest-building +process. Again he interjected the tragic note into her life by +shooting her second husband, only to find her start out in pursuit of +a third, with whom she returned in the course of an hour. He felt that +by this time he had interfered with her domestic happiness as much as +he had any right to do, and suffered her to continue her housekeeping +with her third husband without further molestation. I imagine it would +have puzzled both birds to tell who was the father of the nestlings +who appeared two weeks later.</p> + +<p>Not only do sparrows nest early, they nest often. I suggested to one +of my students that she locate as early in the season as she could the +nest of a pair of English sparrows, which was sufficiently accessible, +and that she keep it under observation at intervals of a few days +throughout the summer. In the fall she came to me with glowing eyes +and gave me her report. "It is simply great," she said. "I never went +to that nest a single time this summer to find it empty. When I first +got there I found four eggs; after a<span class="pagenum"><a name="Page_83" id="Page_83">[Pg 83]</a></span> while these hatched out, and the +young were on the nest until they were old enough to fly; but before +they had left she had slipped a fresh egg among them, ready to start a +new batch. Whenever I saw the nest throughout the entire summer, I +found in it either eggs, or young, or both." Such reproductive energy +as this is hard to beat; compared with this rate of increase, the +ordinary bird is the exponent of race suicide. How can a robin hope to +compete with this family industry? What can a bluebird offer that will +approach such chances of a worthy successor when his work shall be +finished?</p> + +<p>These, then, are the most important points in which the English +sparrow has varied from his sparrow cousins and made of himself the +most successful town dweller in the bird world. He has become clannish +and gained the advantages of coöperation. He has used man's highways +and cars by means of which to expand his area. He has cultivated the +presence of man and thus gained protection from his enemies, food from +man's waste, and nesting sites on man's house. He has assumed a varied +diet. The male has become handsome. He has given up migrating, and +thus secured the best nesting sites. He has learned to produce many +offspring. With all his versatility, why should he not succeed?</p> + +<p>Thrown into competition with our native birds, he<span class="pagenum"><a name="Page_84" id="Page_84">[Pg 84]</a></span> easily beats them +on their own ground. He survives against the competition of birds +which seem to us more estimable in every way. The very fact that he +survives proclaims his superiority over them, and shows that our +criterion is not the one by which nature judges. We like the birds +which serve our purpose. We admire the brilliant plumage of the jay, +cardinal and goldfinch. We love the mellow notes of the woodthrush, +and of the veery, the clear, rollicking outpourings of the bobolink, +the musical love song of the brown thrasher, the cheerful scolding of +the wren. We are fond of the birds who busy themselves taking the +insects out from among our grain and from off our fruit trees. We can +only understand the value of the bird to nature when he is valuable to +us. So, because the English sparrow does little that is to our +advantage and much that is to our annoyance, he is in our estimation a +reprobate and an unending nuisance.</p> + +<p>All sensible bird-men must clearly acknowledge that he is a very +undesirable citizen. I write the above sentence to show that I realize +the whole duty of the bird-lover in the matter of the sparrow. This +pestiferous creature should be exterminated by traps, by grain soaked +in alcohol, or strychnia, by fair means or foul. But personally, I am +taking no share in his destruction. Any bird-lover, after reading the +foregoing ac<span class="pagenum"><a name="Page_85" id="Page_85">[Pg 85]</a></span>count, can scarcely have missed the undercurrent of my +affection for the little rascal. He is a thorough optimist; he is +absolutely persistent; no hardship seems to dampen his ardor. His +heart is valiant above that of most birds so that he has dared to make +of man his near neighbor when other birds consider him their worst +enemy. I love him for it. When I am in the midst of a big city with +its cliffs of offices and its gorges of paved streets, it is to me a +cheer and a delight to see this happy little fellow who has adapted +himself to circumstances against which no other bird, excepting the +pigeon, can cope. I confess that it would be with regret that I should +see him disappear from the landscape. I have missed a long line of +spring peas through his ravages, and he has objectionably decorated +many places about my own home. But I have yet the first violent hand +to lay upon the sparrow, and I doubt whether my hand is ever to be +reddened with his blood.</p> + +<p>I am going to ask bird-men to forgive me if I say that I believe, +although I speak only from general impression, and not from careful +research, that the sparrow within the past eight years has reached his +equilibrium in the neighborhood of Philadelphia and is growing no more +abundant. Meanwhile another and very desirable state of affairs is +arising. Bird love and bird protection are so active in this +neigh<span class="pagenum"><a name="Page_86" id="Page_86">[Pg 86]</a></span>borhood that there is growing to be a new race of birds who lack +the fear of man their ancestors justly had. Under these conditions the +wild birds, which for a while we believed to have been completely +driven out by the sparrow, are rapidly returning to our villages and +towns, and we have many more robins and catbirds, wrens and flickers +than we had ten years ago. We have seen the worst of the English +sparrow; he has now found his equilibrium.</p> + + + +<div class="section_break"></div> +<p><span class="pagenum"><a name="Page_87" id="Page_87">[Pg 87]</a></span></p> +<h3>CHAPTER IV</h3> + +<p class="chapter_subhead">Adaptation for the Individual</p> + + +<p>Among the standard books of the classical curriculum in the +denominational college of thirty years ago was a volume which I +suppose has practically disappeared from such courses. It delighted +many of its students for a reason entirely different from that which +the author meant should be its taking feature. It was Paley's "Natural +Theology." The author started with a story of a watch found by a +savage. This child of nature was supposed to examine its mechanism and +to infer that the watch was made for a definite purpose. As I +remember, he was even supposed to discover that its purpose was to +mark time. It was at least to become clear to his savage mind that +this was no chance object, but was the definite product of a designing +mind. Having brought this hypothetical savage to these conclusions, +the author turned himself to savages nearer home who fail to see +design in nature. The book takes up a great many cases of interesting +facts in animals and plants as clearly showing evidences of design as +did the watch our savage picked up. But the inference we were expected +to<span class="pagenum"><a name="Page_88" id="Page_88">[Pg 88]</a></span> draw was that the design shown in nature argued clearly for a +Designer above nature; in other words, that nature was unintelligible +without God. Everyone in the class believed in God without this +preliminary, and consequently the book was unnecessary, so far as we +were concerned. We started with the condition of mind which the author +hoped to produce. One effect the book did have; in the absence of any +other reputable course in zoölogy, it gave us an astonishing +collection of interesting facts about animals.</p> + +<p>Some of Paley's statements were certainly peculiar. His Malay pig with +its upper teeth wonderfully curved was said to be in the habit of +hanging its head upon a bush while it slept, in order to save the +strain upon its porcine neck. This was too much even for our +credulity. None the less the impression made upon some of us by the +evidence for design in nature has never left us.</p> + +<p>Among many scientists to-day it is supposed to be crude to speak of +purpose in nature, and there is reason for their attitude. But the +statement that there is no such plan conveys to the ordinary thinker a +meaning that is far more erroneous than could possibly exist in his +mind should he believe implicitly in design and purpose. As between +design in the universe in the usual sense of the word, and a purely +accidental connection of events in the universe, there can be no<span class="pagenum"><a name="Page_89" id="Page_89">[Pg 89]</a></span> +doubt as to the choice. The truth is far better expressed by the word +design than by the chaos which is the alternative idea in the average +mind. In these later years we have come to use a different word. We +now conjure in such connection with the word adaptation. In every +animal and every plant the trained eye sees unending examples of +adaptation; that is, of a fittedness to the work it has to do. The +modern scientist feels sure not only that the animal is fitted to his +work, but that he has been so fitted by the work; that the very use he +makes of his organs has determined their structure. This work has +decided that the structure which he has is the structure that shall +survive and shall produce other structures like itself. Adaptation +therefore does not simply express the idea that the animal is adjusted +to its surroundings, but it further suggests that the animal by +gradual process has become thus adjusted. The word adaptation applies +not simply to the result, but also to the process. The scientist does +not consider the animal a final and complete result. He thinks it +still in a state of flux, and so long as its line lasts it will be in +a state of flux. Change is about it on every side, and it must adapt +itself to this change or it will pass away. It may adjust itself, as +has been previously stated, by moving to another environment in which +it feels more at home, but unless it does this, if there come much +change in<span class="pagenum"><a name="Page_90" id="Page_90">[Pg 90]</a></span> its present surroundings, it must either meet the +difficulty by altering itself, or it must give up the struggle. The +alteration is unconscious so far as the animal is concerned. It is +seriously to be doubted whether there is any recognition of the +process on the part of any animal excepting man. But though the +process be unconscious, it is none the less there. Slowly and +gradually the animal and the environment are becoming adjusted to each +other.</p> + +<p>While it is exceedingly difficult to lay our hands on any animal which +is at present visibly changing its structure, it is not hard to find +closely related animals. These are nearly alike in structure in most +respects. In a few points, however, they may differ materially, and +these points are often directly concerned with different habits of +life. Considered in this aspect, these adaptations of a single organ +separately examined form an excellent argument in favor of that +gradual alteration of the entire organism which evolution suggests.</p> + +<p>The most primitive struggle in which an animal can possibly engage is +the effort to maintain its own life and vigor. This struggle will +result in certain adaptations for the individual, adjustments which +make for the safety of the animal himself. These form the subject +matter of the present chapter.</p> + +<p>The farther up the animal kingdom we pass in the<span class="pagenum"><a name="Page_91" id="Page_91">[Pg 91]</a></span> study of adaptation, +the more likely we are to find changes which have but little bearing +on the safety of the individual. They work for the good of the entire +species, sometimes to the distinct disadvantage of the individual. The +King Salmon may make its long run to the headwaters of our western +rivers, deposit its eggs, have them fertilized, and then float down to +death. But it does not die before abundant preparation has been made +for the continuance of the race. Such adaptation for the good of the +species will be considered in the next chapter.</p> + +<p>The first and most important struggle any animal has to enter is the +never-ending battle for its food. Occasionally there is a similar +straining after the air it breathes. But ordinarily air is +sufficiently abundant, except to animals living in the water, where +the supply is always more or less restricted and easily becomes +exhausted. But food is the constant need of every organism, and most +creatures die for lack of it. In this struggle the animal is pitted +against those of his own kind, rather than against those of other +species. Even his brother is his enemy, for he desires the same food. +In many a nest of birdlings one of them fails to reach its development +simply because the parent either is unable to find or it cannot carry +enough food to satisfy all the hungry mouths in the same nest. Before +the nestlings are ready to take<span class="pagenum"><a name="Page_92" id="Page_92">[Pg 92]</a></span> their place in the struggle for life +outside and hunt their own living, one or more of them has succumbed.</p> + +<p>After the battle for food comes the struggle for shelter. For most +animals there is no such thing as shelter. They are exposed to the +inclemencies of the weather and to the depredations of their enemies +without the means of retiring into any situation which might protect +them. In the higher animals, especially when they are warmer blooded +and their bodies must be kept at a higher temperature, some form of +covering has come to be almost universal.</p> + +<p>Though comparatively few animals are prepared to seek shelter from the +cold, all of them have enemies against whom they must battle. These +foes may wish to eat them or may simply wish to get them out of the +way. In either event this struggle is so persistent and so keen that +after starvation it is probably the source of the largest loss to the +animal kingdom.</p> + +<p>Considering first the feeding habits of animals, we find they are +exceedingly varied. Some creatures simply engulf other and more minute +animals, often only microscopic in size, in such quantities as to +satisfy their hunger. Others, feeding upon larger plants or animals, +must have some means of breaking off particles of this food; still +others confine themselves entirely to nutritious fluids, and must have +organs adapted to this particular type of food.</p> + +<p><span class="pagenum"><a name="Page_93" id="Page_93">[Pg 93]</a></span>Insects are so common that anyone, who cares to, may easily verify +what is here described. It will take nothing but a clear observant eye +and a little patience to make out what is suggested. Each of our +common insects has one of two clearly defined habits in the matter of +food. Either it eats solid food, which must be made fine before it can +be taken into the mouth, or it feeds upon liquids. These liquids may +be easily accessible like the nectar of flowers, in which case one +sort of mouth will serve; or they may be the juices inside the tissues +of animals and plants, when an entirely different type of mouth must +be employed in their acquisition. Perhaps the most easily found +representative of the biting type of mouth, which breaks up solid +food, will be seen in the common grasshopper. Doubtless each one of my +readers has at some time taken a grasshopper into his hand, and, +holding the tip of his finger against the insect's mouth, has promised +the creature its freedom on condition that it disclosed its +reprehensible habit of chewing tobacco. The grasshopper surely +complied, and I trust the promiser was as good as his word. The +grasshopper's head is so placed that, while it is at the front of its +body, the mouth is directly on the under side of its head, while the +eyes are at the top of the front of its face. Under these +circumstances it cannot see what is going into its mouth, and this +makes<span class="pagenum"><a name="Page_94" id="Page_94">[Pg 94]</a></span> an interesting variation of conditions to which it must adapt +itself. The means by which it accomplishes this will be clearer if the +mouth of the grasshopper be compared with our own. Our lips are upper +and lower, but the grasshopper has a front lip and a hind one. The +broad front lip is easily seen at the forward side of the mouth. Just +behind it, serving the purpose of our teeth, is a pair of hard jaws +with horny tips upon them, which serve to break small pieces from its +food. While our jaws and those of all other backboned animals work up +and down, so that we may be said to have an upper and lower jaw, the +grasshopper and all of his insect, crab, or spider relations, which +have jaws at all, have them right and left, and they work from side to +side. Behind these harder mouth parts is found a pair of softer jaws, +each of which has on it a little finger-like feeler. With this pair +the insect holds its food while the hard jaws break it to pieces. The +hind lip follows, and is also provided with short finger-like feelers. +The feelers on the hind lip and on the soft jaw are necessary because +the eyes are so placed as not to be able to see what goes into the +mouth, hence the insect must make up for the loss of sight by the +addition of touch. The same type of mouth as the grasshopper has will +be found among the beetles. Here the males sometimes have the hard +jaws so enormously enlarged that they<span class="pagenum"><a name="Page_95" id="Page_95">[Pg 95]</a></span> are known as pinchers and have +given to their owners the name of pinching bugs. All insects with such +jaws as these use them for breaking up solid food.</p> + +<p>A glimpse at the mouth of the butterfly captured on an adjoining +flower will show a most remarkable variation from that seen in the +grasshopper. Practically all of the mouth parts mentioned are present +in this insect, and its early ancestors had their organs practically +like those of the grasshopper. Now they are so modified and united +with each other as to be almost unrecognizable. The pair of soft jaws +has become very much elongated, and they lock together in such a way +as to enclose a hollow space between them through which the creature +can suck its fluid food. Not only have these soft jaws joined +together, but, because they have become so much elongated when not in +use, they must be coiled up like a watch spring and laid between two +hairy lip-like processes which correspond in reality to the two +finger-like feelers of the grasshopper's hind lips.</p> + +<p>The butterfly, lighting upon the corolla of the flower, uncurls this +long "tongue," and through its hollow center pumps up into its crop +the nectar which the flower has stored in its base. When the butterfly +comes to get the nectar from the flower, it rubs upon its own hairy +body pollen from the stamens of the flower and carries it to the +pistil of the next flower<span class="pagenum"><a name="Page_96" id="Page_96">[Pg 96]</a></span> of the same kind which it visits. Most of +us have at some time sucked the nectar from the back of a torn +honeysuckle blossom and approved the taste of the butterfly in this +matter. If the airy creature be watched as it lights upon a flower, it +will not be difficult to see it uncurl this long tongue and probe the +depths of the flower. If the butterfly be taken in the hand and the +tip of a pin inserted in the center of the coiled tongue, it can be +uncoiled without the slightest harm to the butterfly.</p> + +<p>Insects which wish to use for their food the juices of other animals +or of plants do not find them so easy to gather. In the mosquito most +of the mouth parts are developed into slender pointed bristles wrapped +in a hind lip. These bristles serve to puncture the skin of the +creature attacked, while the curled lip serves as a tube through which +the blood may be extracted.</p> + +<p>If, while sitting on the porch on a warm summer evening, mosquitoes +begin to annoy, let one of them at least serve to show his method of +procedure before he is destroyed. Allow the creature to alight upon +the back of your hand and slowly raise the arm until the eye looking +at near range can see the head of the mosquito, which, by the way, is +sure to be a female. Males in this species are entirely harmless. They +never eat after they have grown up; that is, after they are truly +mosquitoes. But the female is very<span class="pagenum"><a name="Page_97" id="Page_97">[Pg 97]</a></span> assiduous. Alternately raising and +lowering her lancets from either side, she pierces, then saws, her way +down through the flesh until she has buried her instruments in her +victim and her head rests against her prey. Now a pumping motion of +the abdomen will be apparent, and this continues its accordion-like +action until it becomes more and more distended. The insect only gives +up its task when the entire abdomen is swollen into a great red ball +of blood. The mosquito will now slowly withdraw its instruments and +retire from the scene, if permitted to do so. If there is any fear of +annoyance from the bite, a drop of ammonia immediately applied will +counteract any irritation which would have been produced by the saliva +of the mosquito. The insect is not intentionally vicious in this +procedure. It is simply gathering its own natural food, though this +does not make it less annoying to us since we are its victims. The +swelling produced after the bite is the result of the action of the +saliva the mosquito injected into the wound. The opening through the +tongue is so small that blood would readily clot inside the tube and +prevent its further usefulness, did not the mosquito inject the +secretion of its salivary glands into the wound. This acts upon the +blood in such a way as to prevent its coagulation.</p> + +<p>Anyone who thinks carefully can add numberless<span class="pagenum"><a name="Page_98" id="Page_98">[Pg 98]</a></span> specializations for +food getting. For instance, primitive mammals have little pointed +teeth which fit them for feeding on insects. In each of the great +order of mammals a special development of these teeth has occurred. +Among the rodents or gnawing animals the front teeth have become long +and chisel-shaped for nibbling. The horse has formed them for nipping, +and his hind teeth for grinding. In the dog the teeth near the front +have become long for tearing his flesh food, while his hind teeth, +working with the motion of scissors, cut it into pieces.</p> + +<p>A second great class of specialization is seen in the changes of habit +that provide the animal with shelter. The home seems so necessary a +part of human life that it is almost impossible to think of an animal +having nothing that in the faintest degree could be called a home. We +at least expect it to have some sheltered place in which it passes +most of its time and to which it returns after its wanderings. The +great majority of all animals have no such home. The place in which we +find them to-day may not be the place in which they will be to-morrow. +All places are alike to them. The ordinary conduct of their daily life +drives them about in the search for food. Their attempt to escape from +their enemies leads them each day into new situations, and they may, +and probably do, have no power to recognize the old location if<span class="pagenum"><a name="Page_99" id="Page_99">[Pg 99]</a></span> they +return to it. When we come to the backboned animals there is a little +more tendency to a stationary location. The sun fish may frequent the +same reach of the stream, the trout may haunt the same pool, year +after year, but a great majority of fishes doubtless move +indiscriminately up and down the stream or about the lake or ocean and +are not found two successive days in the same place. The same may be +said of frogs. For a time a particular frog may have a fondness for a +special bend in the stream, but it is only a temporary fondness, I +believe.</p> + +<p>Our own need for shelter is the prime motive in leading us to build a +home, and this necessity arises first of all because of our warm +blood. What we are accustomed to call cold-blooded animals are not +truly so. Their blood holds practically the temperature of their +surroundings. As the air or the water in which they live grows warmer +or colder the bodies of these creatures alter with it. Consequently +they are active when the temperature is high and grow more sluggish as +the thermometer falls. When the day grows distinctly cold the animals +may go practically dormant.</p> + +<p>Only the birds and mammals have warm blood, and of these the birds are +distinctly the warmer. Whereas the temperature of the mammals runs +from about ninety-eight to a hundred degrees Fahrenheit, that of<span class="pagenum"><a name="Page_100" id="Page_100">[Pg 100]</a></span> +birds lies somewhere between one hundred and five degrees and a +hundred and ten. Creatures which are warmer than their surroundings +must have some protection against chilling. Accordingly both mammals +and birds have clothing. In the case of mammals the covering is fur, +in the case of birds feathers. In some of the tropical animals like +the elephant and rhinoceros, or in man, who has learned to protect +himself in cold regions by making clothing for himself, this hair is +very short, and except where serving for ornament is quite scanty, no +longer being of use as a protection. But the great majority of all +mammals are well covered with a dense coat of hair. In many of those +living in the colder regions there is in reality a double coat. The +fur seal of the Alaskan Islands is so provided. A set of long hairs +deeply fastened in the skin forms a covering, which shows on looking +at the seal. Underneath this layer, and set but lightly into the skin, +is a short coat of very much finer hair known as the underpelt. When +the skin is taken from the seal it is split by machinery into a lower +and an upper layer. When so split the deep-seated pits of the long +hairs are cut, and these hairs come out. The fine underpelt thus laid +bare is what is commonly known as sealskin. Fashion has decreed that +this must be dyed a rich brown, although when taken from the animal it +is nearly mouse gray.</p> + +<p><span class="pagenum"><a name="Page_101" id="Page_101">[Pg 101]</a></span>The birds have need for better clothing. To begin with, their blood is +much warmer, and hence needs better protection from outside cold. In +addition such of them as fly high must be prepared to stand great +variations in temperature. For these purposes birds need a covering of +the finest type. This clothing, in addition, must be extremely light +because the creature must carry it into the air in flight. All of the +requisite conditions are thoroughly met by the feather, which is the +lightest and warmest clothing known to man. If at night we wish, +regardless of expense, to keep ourselves warm with the lightest and +warmest of covering, we send to the Arctic Sea, and from the breast of +the eider duck we pluck the down which lies between the warm blood of +the duck with its temperature of one hundred and seven degrees and the +water in which the iceberg floats.</p> + +<p>Young mammals and birds, before their clothing has well formed, are +naturally susceptible to cold; this leads to the first genuine +approach to a home among animals lower than man. Birds lay their eggs +long before the creatures inside of them are ready to emerge. +Accordingly they have learned to build nests in which to place these +eggs, and to protect them from the outside air; meanwhile the bird +keeps the eggs warm by close contact with its own body. The lowest of +the birds may lay their eggs simply on the<span class="pagenum"><a name="Page_102" id="Page_102">[Pg 102]</a></span> ground without any special +protection. As we rise in the scale of the bird world we find nests +provided for the eggs. These nests become increasingly complex and +specialized, until we reach the oriole's home with its wonderfully +woven mass of fiber, which, in spite of its apparent looseness, +supports well the weight of the mother bird and of her eggs. The +robin, not content with making a woven basket, plasters it with clay, +and makes an absolutely impervious nest.</p> + +<p>When we remember that both mammals and birds are the modern +descendants of cold and scaly reptiles of an earlier geological time, +it becomes interesting to compare their clothing. Evidently in the +mammals hairs began to come out between the scales. Gradually the +scales became fewer and the hairs more abundant until finally the +scales have all disappeared, except those that remain as the claws on +the toes. The ancestors of the birds, on the other hand, boldly +transformed their scales into feathers.</p> + +<p>Another need for shelter arises in connection with the approach of +winter. This problem of withstanding the cold season is complicated by +the presence of two new factors. First and most directly, the cold +itself is a distinct obstacle to the comfort of many of these +creatures; as a secondary result of this cold, the food of many +animals disappears entirely in winter.<span class="pagenum"><a name="Page_103" id="Page_103">[Pg 103]</a></span> Most of our birds meet this +difficulty by changing their base of operations. When the north grows +cold these creatures fly to the south. Some of their migrations cover +enormous stretches of country. Our bobolink, so well known and loved +by all watchers of spring migrations, passes twice a year between the +latitude of New York and Rio Janeiro. One of our most careful students +of bird migration says that the Golden Plover makes, twice each year, +the long journey from the Arctic shores of North America to the plains +of La Plata.</p> + +<p>Different fur-covered animals have specialized to meet the winter by +any one of three different methods. They may brave it out, hunting for +their food as best they can all winter long. Such a course is pursued +by the rabbit. Again like the squirrel, they may store large +quantities of food during the summer, and on this provender they may +subsist during winter, remaining for most of the time near their +hiding-places, which, however, they may frequently leave upon warm +days. A third method is less common, but very interesting. The +groundhog or woodchuck is the best-known example of the group. It +remains asleep, or, as it is technically known, dormant, during the +winter. This stupor is more profound than ordinary sleep, and from it +these animals awaken with difficulty. It is needless to remark that +the groundhog's<span class="pagenum"><a name="Page_104" id="Page_104">[Pg 104]</a></span> behavior on the second of February has no relation +whatever to the weather we are to have later in the season. This is +coming to be pretty generally understood. While the newspapers each +year comment upon the groundhog and his shadow upon that day, year by +year the notice has more of humor in it, and fewer people pay any +attention to it.</p> + +<p>As for the backboned animals which are cold-blooded, these must, +unless they are fish, give up the struggle completely, bury themselves +in out-of-the-way places, and go worse than dormant. They often become +absolutely cold and stiff. In the case at least of fish, it is quite +possible for them to be frozen stiff, even to be enclosed in cakes of +ice, and still to recover if the encasement is not too long continued. +But the snakes, the turtles, the toads, the lizards, all are hidden +beneath the ground waiting in absolutely unconscious rest the return +of warmer weather.</p> + +<p>After the need for food and shelter comes the continually recurring +necessity on the part of almost every type of animal to escape from +the unwearying persecution of higher creatures which would feed upon +it. The whole creation is a constant network of animals which prey +upon each other. It is the fate of a great majority of all creatures +to fall victim to other animals to whom they serve as food. +Accordingly na<span class="pagenum"><a name="Page_105" id="Page_105">[Pg 105]</a></span>ture has concocted many devices by which she assists +her favored children in escaping this relentless persecution. Perhaps +the most widespread means which animals have developed in order to +elude their enemies lies in the possession of power to escape their +attention. Two different factors may contribute to this end. The first +of these consists in the practice on the part of many animals of +remaining absolutely quiet in time of danger. This instinct seems to +be nearly universal. The first impulse of most animals upon +discovering danger is to remain absolutely motionless. The eye +detects, with ease, objects in motion. These same objects might +entirely escape attention were they quiet. A mouse could remain in the +corner of a room for a long time without attracting the eyes of the +occupants of the room. Let it but scamper across the corner, and at +once it is discovered. It is quite conceivable that early animals were +divided in the matter; that the impulse of some was to escape from +danger, while others, frightened by the presence of the enemy, +remained absolutely still. Each plan has succeeded. Those which, on +running, ran fast enough to escape became the parents of others like +themselves, led eventually to a line of animals in whose speed lay +their safety. Those, however, which attempted to escape, and failed +because they were not swift enough, had their line cut off, and were +thus<span class="pagenum"><a name="Page_106" id="Page_106">[Pg 106]</a></span> less likely to be represented in the following generation. The +constant result of errors along this line would be to destroy the slow +and preserve the swift, and in the course of time it is quite +thinkable that only the swift should remain. As the movements grew +more and more keen, even the slower of these would pass out, thus +tending always to produce the succeeding generation from those who +were most rapid, and hence most likely to transfer to their children a +similar power.</p> + +<p>But there is another tendency of animals which leads them when +frightened by their enemies to remain quiet. If this impulse is obeyed +thoroughly enough, it is easy to see how the owner of this habit might +entirely escape detection by his enemy. Any restless animal unable to +restrain his nervous agitation naturally betrays his presence and is +picked off. The result of evolution along this line would be the exact +reverse of the preceding. Those that lay most absolutely quiet would +be the parents of succeeding generations, while those who were slow in +coming to rest, or were indifferent about remaining quiet, were picked +off, and their tendency eliminated from the future of the species. In +this way many animals have come to keep entirely quiet in the presence +of danger. It is not a sign of high intelligence. As a matter of fact, +it is rather a stupid procedure, so far<span class="pagenum"><a name="Page_107" id="Page_107">[Pg 107]</a></span> as the animal itself is +concerned, but it is a preserving stupidity, and many animals have it.</p> + +<p>The "June Bug" (which is not a bug, but a beetle, and arrives in May) +has this interesting habit of keeping quiet. If in its flight it +strikes the globe of an electric light, it falls at once to the +ground, and remains perfectly quiet for a time. After a short interval +it recovers and starts out to regain its previous activity. But this +recovery is by slow stages, and the whole procedure on its part looks +exceedingly stupid.</p> + +<p>The little snake with flattened and expanded head, known as the +blowing viper, or puff adder, is one of the most amusing +representatives of the tendency to "play dead" that could well be +found. If you strike him the faintest blow with the lightest stick, he +at once goes into apparent convulsions, in which he seems to suffer +the greatest agony. Then, throwing himself upon his back, he, to all +appearances, yields up the ghost. If, however, you retire but a slight +distance and keep your eye upon him, you find that his ghost returns +after a comparatively short absence, and he slinks away out of danger. +This is the most effective exhibition of this kind with which I am +acquainted.</p> + +<p>As for the habit of "playing 'possum" on the part of our opossum, the +trick would seem to be particularly inane. The truth of the matter is, +what is at<span class="pagenum"><a name="Page_108" id="Page_108">[Pg 108]</a></span>tributed to an unusual brilliancy on the part of the +creature is positively unusual witlessness. The animal has an +exceedingly small brain, as compared with that of a dog of similar +size, and to anyone who knows brains at all this particular organ +would not be looked upon as furnishing its owner much ability. The +fact is that the opossum has exceedingly small wit, and this little +deserts it in an emergency, as a result of which he grows helpless and +motionless. This is often supposed to indicate great wisdom. There may +be wisdom in it, but it is the wisdom that lies back of all nature. It +certainly is not the wisdom of the opossum.</p> + +<p>Man himself possesses to a marked degree this impulse to keep quiet in +danger. The man from the country who is visiting the large city, +suddenly startled by the "honk" of the auto horn, finds his power of +movement promptly arrested, and he is not unlikely to be struck and +injured by the machine from which the city dweller would easily +escape. This is not particularly to the credit of the city dweller, +who, when in the country, may find himself similarly startled by the +sudden appearance of the calf, the pig, or the sheep. The bull, which +a country boy, accustomed to him from childhood, will drive with a +willow switch, is a source of terrified concern to the city man.</p> + +<p>While the trick of keeping quiet serves many an animal in time of +danger, there is another device for<span class="pagenum"><a name="Page_109" id="Page_109">[Pg 109]</a></span> escaping attention, far more +common and widespread throughout the animal world. The eye does not +easily see an object if it is colored like the background against +which it stands. A host of animals find their main safety in being +indistinguishable in color from the surface on which they live. There +are many biologists who seriously question whether protective +coloration, as Darwin called it, is as effective as he believed it. In +some quarters it is the present fashion to doubt protective coloration +entirely. No one has yet shown any principles which will better +explain the great color scheme of the animal world, and until such +explanation is forthcoming I believe it will not be wise for us to +discard the idea of protective coloration. No doubt it has been +overworked by enthusiastic believers in its efficiency. At the same +time, to overlook it completely, is, I believe, to make a greater +error. I have little doubt that when the broader explanation comes, +which will satisfactorily explain the color scheme of the animal +world, the idea of protective coloration will be found, not so much to +have been wrong, as to have been but partial. It will be included +under the broader principle which takes its place and will not be +supplanted by it.</p> + +<p>The idea of protective coloration is that very many animals have +ordinarily come to be colored like the background on which they live. +The process has<span class="pagenum"><a name="Page_110" id="Page_110">[Pg 110]</a></span> taken many generations, and is very slow, but is none +the less sure in the end. In most cases the animal is probably +entirely unconscious of this point in its favor, and usually it does +nothing to assist the deception. The result is none the less effective +because the animals themselves are unconscious of the process. The +cabbage worm is green in color like the cabbage. This does not mean +that it got green by eating cabbage or by longing for greennesses. +Through long years the enemies of the cabbage worm have been picking +it off the plants on which it fed. This does not imply that cabbages +as we know them are very old, but cabbage worms doubtless ate the +leaves of the sea-kale long before man had cultivated it into cabbage. +During all these years the enemies of the caterpillars, generally in +the shape of birds, have been assiduously gathering them up.</p> + +<p>When we see how much the various members of the same human family may +differ in complexion, how much the various pigs in the same litter may +differ in size and in coloration, it is easy to understand that among +these caterpillars which have eaten the cabbage there must have been +considerable color variations. I do not imagine for a moment that the +birds had any preference for any particular color in their cabbage +worms. They took every caterpillar they saw, but they naturally first +saw those that were least like the<span class="pagenum"><a name="Page_111" id="Page_111">[Pg 111]</a></span> background on which they lived. +The only caterpillar which was effectively hidden from his enemy was +the one that was indistinguishable on the leaf. If it escaped in this +way, the probabilities are that it would produce young which would be +at least a little more likely to be green in color than the progeny of +its darker-colored brothers and sisters. By this continued process the +birds steadily weed out the darker-colored specimens. There would +result, in the course of time, a race of caterpillars, whose ancestors +for so many generations back had been light green in color, that there +is little likelihood of any of the older and darker forms turning up +again. In the course of time all dark tendencies will have disappeared +from the family and practically all of the group will be light green. +Any sport or variation in the shape of greater conspicuousness would +fall a quick prey to the enemy and its line be cut off forever.</p> + +<p>The same sort of activity has resulted in the peculiar green color of +the katydid. This creature lives chiefly upon the leaves of trees and +shrubs. This insect is so large that, even though it is leaflike in +color, it might still be conspicuous. As a result those katydids whose +wings were most like leaves in form were least likely to be picked up +by the passing bird. This sort of protective appearance is intensified +by exactly the same means as that which brought about protec<span class="pagenum"><a name="Page_112" id="Page_112">[Pg 112]</a></span>tive +coloration. The katydid least leaflike in appearance was eaten first. +Thus those most leaflike remain until the last, and are most likely to +produce young. Again, it was not the fact that they lived among leaves +which made them look leaflike, but it is because they look like leaves +that they escaped being devoured.</p> + +<p>The katydid has materially assisted in its own preservation by being +active chiefly at night. In the daytime it keeps comparatively quiet. +Thus seated upon a twig, especially if hidden among the leaves, it is +almost unnoticeable. At night, however, it moves about more freely, +seeking its food and eventually its mate. At such times it becomes +distinctly more conspicuous because its wings are steadily fluttering. +The hind wings are filmy and are very light green. The creature looks +most ghost-like as it flies through the evening air.</p> + +<p>A very similar history lies back of the coloring of the ordinary toad. +Though descended from the frog, and originally a creature of the +water, the toad has long since adapted itself to live upon the dry +ground. It still produces its young in the water as it did when a +frog. Whereas the childhood of the frog, that is, its tadpole stage, +is very long and it assumes its adult form comparatively late, just +the reverse is the case of the toad. The young hasten through their +tadpole stage within a few weeks, and assume the shape of<span class="pagenum"><a name="Page_113" id="Page_113">[Pg 113]</a></span> the parent +toad when about big enough to cover your little fingernail. Now they +leave the water and seek dry land. Naturally they make the change when +the land is damp, that is, after a warm spring rain. People seeing +these multitudes of little toads hopping around over a bare spot of +ground, and remembering the rain of the night before, insist that it +has rained toads. Of course it never rains down anything which cannot +evaporate up. The stories of showers of toads and of earth worms, with +an occasional fish, or even creatures of larger size, are all pure +myths. There are conceivable tornadoes after which there might be a +shower of such creatures, but at such a time it is likely also to rain +barn roofs and buggies. You may be sure that toads which come down in +the rain are dead after they strike the ground.</p> + +<p>The little toads started out, perhaps a hundred at a time, from the +small pool in which their eggs were laid. These creatures find dragons +on every side. The gartersnake comes along and gets his first toll; +the heron follows him and takes such as catch his hungry eye; the +turkey gobbles up his from what are left. By the time the toad-eating +creatures in the neighborhood have taken such as they found, there are +very few remaining. These doubtless have been left for a very good +reason, generally because they were not noticed. This was because they +looked like<span class="pagenum"><a name="Page_114" id="Page_114">[Pg 114]</a></span> the ground on which they sat, and because they kept +perfectly quiet while the enemy moved about. This process has gone on +so long that the toad has come to be astonishingly well protected by +its resemblance to the ground. This likeness it intensifies by its +interesting habit not only of keeping entirely quiet, but of dropping +its nose to the ground, instead of sitting high on its front legs, as +it does when not in danger.</p> + +<p>I have noticed that if a snake and a toad be placed in the same cage, +when the snake approaches to capture the toad the toad drops into a +squatting position, and is very likely to blow himself up until he is +rounder in outline than he was before. Whether this is a deceptive +trick which makes him the more resemble a stone is more than I can +say. I do not remember having seen our eastern toad do it. I have seen +it happen a number of times in the laboratory of a Colorado +naturalist, and it is quite possible that in the open country more +sparsely covered with vegetation than is our ground in the east this +inflating device may serve the toad more effectually than if it kept +its own outline.</p> + +<p>Even among creatures far more active than the toad and the katydid an +inconspicuous color must certainly result in distinctly better +protection. Everyone knows the jay and the cardinal when first he has +seen them, if only he has a slight acquaintance with their<span class="pagenum"><a name="Page_115" id="Page_115">[Pg 115]</a></span> pictures. +They are so conspicuous that we recognize them at once. More common in +my region than the jay or the cardinal is the red-eyed vireo. This +creature moves industriously in and out among the leaves of our trees. +It is persistently in motion, is nearly constant in song, and is a +bird of fair size, being larger than our English sparrow, though +smaller than a robin. Many a nature lover will recognize twenty-five +or thirty birds at sight without any difficulty, and not know the +vireo. Yet the vireo is more common than two-thirds of the birds he +knows. There can be but one reason for this; the bird is +inconspicuous. The olive-green of its back, with its light under +parts, serves to hide it completely amid the foliage. Even the +bird-lover learns to find it first by its jerky song, and then by +watching for its movements among the leaves.</p> + +<p>One aspect of protective coloration has been brought to our attention +by the artist, Mr. Abbott N. Thayer. He first clearly explained why it +is that animals are usually so much lighter on the under side than +they are upon the upper. Mr. Thayer proves his position by taking some +ordinary cobblestones and painting one of them a uniform color and +placing it upon a board painted the same color. One would think the +stone would be inconspicuous; as a matter of fact, is quite easily +seen. The underside of the stone, turned<span class="pagenum"><a name="Page_116" id="Page_116">[Pg 116]</a></span> away from the light, is so +shaded as to mark a distinct boundary between the stone and the board. +Another cobblestone was colored on its upper side like the board, but +the color faded into a lighter and lighter tint until the bottom of +the stone was nearly white. This stone, placed upon the board, was at +a short distance nearly invisible. In other words, although the +pigment was actually lighter on the under side, it was so much less +intensely illuminated, that the result was the same in tint as the +other side under the clear sharp light of the sky.</p> + +<p>Many a person, looking down into the water from a bridge, sees nothing +whatever of the fish in the water below, because their backs are +exactly like the bottom of the stream. Suddenly one of the fish, by a +quick movement, turns its lighter under side over in such a way that +it is clearly illuminated from the sky. Immediately a flash as of +silver strikes the eye of the onlooker and makes him aware of the +presence of the fish which had previously been undetected. If rendered +thus suspicious, the observer will carefully examine the bottom of the +water, he may quite likely find dozens of fish which had previously +escaped his attention.</p> + +<p>Nature is very versatile. So many of her apparently chance ventures +have proved successful that she has retained many devices by which her +children<span class="pagenum"><a name="Page_117" id="Page_117">[Pg 117]</a></span> may be safe. One of these, which is doubtless often quite +effective and may serve to save an animal's life, is that of being +able to emit an odor so nauseating as to offend the enemy's sense of +smell, and doubtless remove the keen edge of his appetite. It is not +uncommon among the group of insects properly known as bugs to possess +an exceedingly unpleasant odor. Anyone who has handled a squash bug +will know exactly what I mean, and there are other members of the +group not so common as the squash bug, which, at least to the human +nose, are distinctly offensive. Some of the beetles also save +themselves by this device.</p> + +<p>One of the most interesting developments of this peculiarity is found +in the case of the common skunk. This creature has in each groin a +gland capable of secreting a highly offensive fluid. Ordinarily this +liquid is kept safely within its sac, and for a long time none of it +may escape. When closely cornered, the skunk will turn its tail toward +the enemy and with a quiver and a flip of his tail it can guide the +openings of two little tubes that come out along the root of the tail +in such fashion as to eject the fluid in a fine and foul-smelling +stream against the animal from which the skunk would escape. Once +fairly hit by this fluid, I imagine most animals will drop the skunk. +A dog surely will, and will hate himself for having made<span class="pagenum"><a name="Page_118" id="Page_118">[Pg 118]</a></span> the attempt +to capture anything which must be so ignominiously allowed to escape. +If ones clothing is well saturated with it, it is nearly useless to +hope to remove the odor. A dog will carry the smell for several weeks. +For a long time it will be so strong as to make him an unfit denizen +of the house. Even swimming in deep water does not remove it. After +two weeks, although he may seem to be practically free from the odor, +a light rain will bring it all out again and make him nearly as +offensive as before.</p> + +<p>Not as prompt in its action, but in the end nearly as effective, is +the protective device which the toad sometimes uses to his distinct +advantage. May I be pardoned a personal account of this particular +feature. It was my good fortune to be for a short time a student in a +class taught by Edward Drinker Cope, one of the most brilliant of our +American biologists. Prof. Cope mentioned in class the fact that the +Batrachians (the group to which the toad belongs) have in many cases +the power to emit from their skin a fluid which is sufficiently +nauseous to deter an animal from eating the creature that secretes it. +Upon such authority as this, I had no hesitancy whatever in repeating +Cope's statement. One morning I had a class in the field studying the +ground ivy, whose dainty blue flowers were lifting themselves out of +the dewy grass. While we were thus engaged, a<span class="pagenum"><a name="Page_119" id="Page_119">[Pg 119]</a></span> toad joined the circle. +He came out of his dewy retreat clean and fresh from his morning bath. +I took him in my hands, and made him the subject of an immediate +lesson. I showed to my pupils his eyes and his interesting method of +handling them, his tongue and its strange insertion; showed them how +to look into his mouth and look up his ears to his ear drums, and +pointed out many other interesting facts. Then I told them how Cope +had said that the toad had power to emit from its skin a fluid so +nauseous that many an animal hesitates to eat it. This is the first +peculiarity I had mentioned which I had not myself observed, and a +scientific qualm came over my conscience. Why had I never verified +this statement which I had so frequently repeated? On the impulse of +the moment, with the bright, clean skin of the creature fresh from the +dewy grass, making it less than usually repulsive, I ran my tongue up +its back only to find that it had no taste whatever. I was of course +surprised, but I was not foolish enough to deny, as the result of one +observation, the statement of a good scientist. The observation, +moreover, was one which I naturally did not care to repeat with any +frequency. Of one thing I was sure, toads do not always have an +unpleasant taste.</p> + +<p>A year later I had a class down by the side of a neighboring pond. The +pool was not an attractive<span class="pagenum"><a name="Page_120" id="Page_120">[Pg 120]</a></span> one, and I had picked from it a more than +commonly unappetizing looking toad, which proved to be a mother which +had not yet laid her eggs. As I held her in my hands and exhibited her +various points to my pupils, I told them of Prof. Cope's statement. I +also told them of my unsuccessful attempt the previous year to verify +the statement. I added, however, that I would not repeat this +experiment on this unappetizing specimen. Hereupon the toad not only +exuded, but squirted, from a gland over her left shoulder blade a +fluid, milky-like in appearance, and forming a jet as thin as a +needle, but ejected with force enough to strike my face, which was at +least fifteen inches away. I moistened my finger on my tongue, lifted +the fluid from my cheek, and tasted it. Cope was right. A toad can +exude a most nauseous fluid. Horsechestnuts extracted and distilled +might possibly provide something as bitter. Why did I not find this in +the preceding case? I have too few observations on which to base a +conclusion, but I have a suspicion as to the reason. In the case of +the toad which spurted the fluid in my face, we had a creature with +whose life were tied up the lives of her many offspring, to be +produced from the eggs she was so soon to lay. Under conditions like +these, nature is more than commonly careful of her children. Whether +this be the reason or not, toads do not al<span class="pagenum"><a name="Page_121" id="Page_121">[Pg 121]</a></span>ways have an unpleasant +taste, but when they do it certainly is most unpleasant.</p> + +<p>There remains to be considered the most effective plan yet mentioned +of escaping the enemy, and that is of really escaping. In all the +devices we have considered thus far the enemy is eluded. When the +creature lies quiet, or finds safety in its protective coloration, or +in its bad taste, or unpleasant odor, it still remains in the presence +of the enemy. A more progressive plan altogether is to escape the +enemy by flight. The great advantage of this plan lies in the fact +that the acquisition is valuable for every purpose. The creature then +can escape the enemy, can range widely for food or for a mate. This +gives it an enormous advantage in the struggle for life. The power to +fly, in insects, was doubtless originally gained in the attempt to +escape the enemy. Among many of the lower animals it is nearly the +only purpose that flying serves. Later on it enables the animal to +pass from one food locality to another. In a few creatures it plays an +effective part during the mating season. These last are probably both +derived powers, and the original function was that of escape from the +enemy. The grasshopper has grown its long legs to serve him for +safety, and through them it is helped along, moving about chiefly by +leaps when it wishes to go any material distance. It is only toward<span class="pagenum"><a name="Page_122" id="Page_122">[Pg 122]</a></span> +the very end of its life that the grasshopper has wings, and then they +serve probably to aid in the search for a mate. Among the birds flight +began simply in sailing out of the trees, into which the creature, +still half lizard, had crept to escape its enemy. The earliest bird +known to us had comparatively insignificant wings. There was really +more support in its tail than in its wings, and this would distinctly +indicate that it glided more than it flew. It had claws also upon its +wings, and it was probably the case that this creature crept into the +trees, at least in its earliest forms, and sailed down in a manner not +unlike that employed to-day by the flying squirrel. From such simple +beginnings came the wonderful power of flight in the birds.</p> + +<p>Among mammals the attempt to escape from the enemy has led to an +interesting development, which will be more fully explained in a later +section when we speak of the history of the horse. The early mammals +walked flat-footed, as we do on our feet and as the raccoon and the +bear do on theirs. Gradually, however, as their enemies became more +fierce and better able to injure the larger mammals, the latter gained +in power of flight, and this gain consisted first in rising from the +toes, lifting the heels completely off the ground. At the same time +the leg and foot were gradually lengthened. Doubtless in this way the<span class="pagenum"><a name="Page_123" id="Page_123">[Pg 123]</a></span> +fleet animals, like the deer, the horse and the giraffe, first came by +their long legs. Constant elimination of the short-legged ones, by the +pursuing enemy, resulted in the selection of the long-limbed ones for +breeding purposes, and hence to the ultimate elongation of the legs of +the species.</p> + +<p>The method of escape from the enemy involves cowardice. "He who fights +and runs away may live to fight another day," and so it may be the +part of wisdom in the weak creature to escape from his enemy by +flight. It is a far more estimable process, from our standpoint at +least, to stand against the onslaught of the enemy and beat him upon +his own ground. This end is secured in many animals by acquiring horns +or by lengthening certain of the teeth. The horn is a very ancient +instrument of defense. When the reptiles ruled the land horns were not +uncommon. They consisted in those days of hardened scales, which +lengthened and fastened themselves over a core of bone. Such an +old-fashioned instrument, sometimes made of newer materials, still +remains the defense of a number of animals. The rhinoceros has upon +his nose a lengthened projection, which is what might not improperly +be called hair glued into a cone. This enormous horn is a frightful +weapon, both of offense and defense, and, when backed by the terrible +weight of the body of the rhinoceros, it can do as<span class="pagenum"><a name="Page_124" id="Page_124">[Pg 124]</a></span> deadly work as +almost any instrument of destruction known to animals below the grade +of man. But, after all, this is an old-fashioned method, and the +rhinoceros is a relic.</p> + +<p>Among the carnivorous animals the teeth, which were developed first +chiefly for the tearing of flesh in its consumption, became effective +for their courageous owners. Because these tearing teeth are well +developed in the dog they have come to be known as canine teeth. +Usually where an animal can use its teeth effectively for offense or +defense, it is the canine teeth that are thus modified. The cat has +developed them better than the dog, and one of the cats of a bygone +geological period had canine teeth so magnificently enlarged and so +sharp at the back as to give this frightful creature the name of the +saber-toothed tiger. The long teeth in the upper jaws of the elephant, +commonly known as tusks, are not canine teeth. The elephant has +completely lost his canines. His tusks are his incisors, and they have +developed as have almost no other teeth in the mammals.</p> + +<p>These are only a few of the numberless devices nature has evolved for +furthering the success of her children. There are so many others that +to many of us they form almost the chief point of interest in our +study of a new animal, or our closer observation of an old friend.</p> + + + +<div class="section_break"></div> +<p><span class="pagenum"><a name="Page_125" id="Page_125">[Pg 125]</a></span></p> +<h3>CHAPTER V</h3> + +<p class="chapter_subhead">Adaptation for the Species</p> + + +<p>The strife, as we have described it thus far, is a purely selfish +struggle. Every point gained is a point favorable to the welfare of +the individual animal. But nature is uncommonly careless of the +individual unless the advantage gained is also of use to the species +as a whole. Very often the life of an animal ceases when provision has +been made for its young. The male garden spider may have a long and +dangerous courtship, in which the uncertain temper of his ladylove may +lead her to bite off four or five of his eight legs. But her +ingratitude is not yet complete. He may have barely accomplished his +desperate purpose of fertilizing her eggs at all hazards, when she +ends the process by eating him. The male bumblebee fertilizes the +female in the late summer and then dies. She does not lay her eggs +before the next season. So it happens that no bumblebee ever sees its +own father, and no father bumblebee ever sees his own children. In the +honey bee the male, which has been fortunate enough to fertilize the +queen, pays for his honor by death<span class="pagenum"><a name="Page_126" id="Page_126">[Pg 126]</a></span> within the hour. Superfluous +bachelors, among the honey bees, when the bridal season has passed, +are driven from the hive to die of starvation.</p> + +<p>An animal need not always be successful himself, but it is more +essential that he hand down his successful traits to those who come +after him. It is more important for the future generation that an +animal should have had it in him to do great things, though he himself +really have never done them, than that he should have learned to do +great things on a meager original endowment. Not what an animal +accomplishes is important to his children, but what he has it in him +to accomplish. Accordingly Nature is full of devices by which those +who have proved their original endowment by winning out in the +struggle shall hand on this endowment to a subsequent generation. In +other words, Nature is anxious that they may successfully mate. Here +we are again on distinctly debatable ground. Darwin himself believed +thoroughly in what he called sexual selection. It is the essence of +this idea that the males and females have grown unlike, more +technically have developed secondary sexual characters, through the +choice of the mating pair. It would usually be the more serious loss +if accident should come to the female, for she may carry fertilized +eggs for some time. Hence, if both sexes may not become attractive, it +is usually the male that de<span class="pagenum"><a name="Page_127" id="Page_127">[Pg 127]</a></span>velops fine colors, ornamental appendages +or a captivating voice.</p> + +<p>An interesting reversal of this process has taken place in civilized +man. His more savage ancestor adorned himself more lavishly than he +permitted his mate to do. With the advance of civilization man has +undertaken to defend his own mate most valorously. The result is it is +safe for her to be beautiful. Under these circumstances, however, it +is more necessary to her welfare that her consort be vigorous rather +than that he be handsome. Hence in the human species beauty has become +the prerogative of the woman, and this is increasingly the case the +higher the civilization. Whether woman suffrage and self-support will +reverse this process remains to be seen. There are indications that +point that way.</p> + +<p>There are many biologists who are at present expressing serious doubt +as to the validity of sexual selection. As in the previous cases of +protective coloration, I believe it will be wise for us to retain, +even though with an interrogation point behind it, the idea of sexual +selection until such time as those who object to it have furnished us +with another theory which will more nearly account for the observed +facts. While entirely conscious of the possibility that there is a +weak spot in the theory, we will still tentatively hold to sexual +selection. The fact that beauty in<span class="pagenum"><a name="Page_128" id="Page_128">[Pg 128]</a></span> women is so intensely attractive +to man, and that vigor and manliness in man are so attractive to +women, leads us to infer that among the lower animals, although of +course in a vastly less degree, vigor and beauty are also attractive. +The weakest point of the position lies in the fact that it probably +presupposes a higher degree of capacity for appreciation on the part +of lower animals than they possess. Those who deny the truth of the +theory laugh at the idea that a butterfly can see clearly enough and +care enough for what it sees to notice whether its mate has wings of +one type or of another. The size, number and position of the spots on +the wings of many butterflies are so nearly constant that they cannot +of themselves have been entirely determined by the choice of the +insect. Yet this may not preclude the possibility of the fact that, +while the spots were produced through some other agency, certain types +of them were selected by sexual preference.</p> + +<p>If attractive coloration is effective anywhere in the animal world, it +will possibly be found among the insects, but it is especially likely +to be found among the birds. Very many field workers in these groups +feel quite sure of the value of attractiveness. When butterflies chase +each other up and down, circling and doubling, following each other +for long distances, it would certainly seem as if they were pleased +with<span class="pagenum"><a name="Page_129" id="Page_129">[Pg 129]</a></span> each other's appearance. Some naturalists, especially those who +have worked chiefly in the laboratory, insist that it is the odor, not +the color of these insects, which is attractive, and some experiments +which have been made would seem to point in this direction. But the +creatures experimented upon most carefully were night-flying moths, +and it is quite possible that the sense of sight in the night-flying +moths has lost its vigor.</p> + +<p>The great difficulty in understanding sexual attraction in insects, as +based upon beauty, lies in the undoubtedly lower development of their +nervous activity; in other words, in the apparent absence of anything +worth calling mind. I think no one imagines that a butterfly, looking +upon two other butterflies who are competing for her affections, +deliberates between them and determines to admit to the circle of her +friendship the more brilliantly colored male. Moths are so +irresistibly attracted to a light as to fly into it without apparent +power to withstand its influence. They repeat the flight again and +again until they are destroyed. If they react so vigorously to the +stimulus of the light, it seems not impossible that they may also act +vigorously to the stimulus of color pattern, and that the male most +beautifully colored, according to the nervous ideal of the female, +should win her unconscious regard. At least it is certain<span class="pagenum"><a name="Page_130" id="Page_130">[Pg 130]</a></span> that, in +very many of the butterflies and moths, the attractive coloration is +chiefly displayed when they are moving actively about; and when they +alight and their enemies can the more easily capture them, they +conceal their brilliant colorings. Most butterflies are very brilliant +on the upper surface of the wings and very much duller on the under +surface. Hence in flight they show their colorings exquisitely, but +when they alight, and are thus more likely to be captured, they fold +the brilliant surfaces together in an upright position. In this way +not only is the dull side of the wings placed outward, but the wings +themselves are placed edgewise to the sky, and it is from this +direction that their enemies, the birds, are most likely to see them. +Once upon the wing these creatures display their beauty with much +greater safety because they can escape the birds very readily by use +of their exceedingly jerky flight. The butterfly's motion is as +irregular as any we have except the bat's. This eccentricity is one +great element in their safety, and makes it less dangerous for them to +display their attractive colorations.</p> + +<p>One very large group of the night-flying moths have been named the +"underwings," because of the fact that their hind wings are very much +more brilliant than the front, and in lighting they fold the dull pair +back over the bright, completely concealing them.<span class="pagenum"><a name="Page_131" id="Page_131">[Pg 131]</a></span> These creatures are +in the habit of resting in the daytime against walls, or stones, or +the bark of trees. The similarity in color between their front wings, +which alone show while sitting, and the background on which they rest, +is most remarkable. One may pass them again and again, although they +are of considerable size, and not notice them at all. Once let them +display their hind wings and the brilliancy of their color always +attracts immediate attention.</p> + +<p>It is among birds, however, that brilliant coloration serves its most +effective purpose. The birds are alert, exceedingly quick of sight, +and are much more discriminating than insects in almost every respect. +It is not so impossible that these creatures might even voluntarily +prefer a distinctly more brilliant mate, though the voluntary +character of the process is not essential to its success. Men +certainly are constantly attracted to women for whose charm it would +puzzle them to account. If this is true with regard to men, it is +certainly probable that birds would be largely influenced by phases of +attractiveness, of which they were observant, but unconscious.</p> + +<p>Certain it is that in many birds the males are far more beautiful than +the females. Perhaps the commonest illustration, and, at the same +time, one of the best is found in the so-called red-wing or swamp +blackbird. The male of this creature is a brilliant<span class="pagenum"><a name="Page_132" id="Page_132">[Pg 132]</a></span> black, excepting +that upon the angle of the wing, spoken of roughly as his shoulder, +though in reality it is equivalent to our wrist, there appears a +splendid orange patch with a border of lemon yellow. When he folds his +wing he pushes this colored angle of the wing so deftly under the +feathers of his shoulder as almost to conceal it. When in flight the +bird is exceedingly conspicuous, showing, with every bend and twist of +his body, his gorgeous epaulets. Meanwhile, the female is likely to +pass unnoticed. She is dull in color and streaked like the grass among +which she lives. During the mating season the male hovers about her, +swaying from side to side in such a way as certainly to make it appear +as if he realized his good points and was bringing them to bear as +effectively as he knew how. After his mate has nested and is rearing +her young, it would appear that the male uses his brilliancy to lure +the observing enemy away from the nest containing his wife and +children.</p> + +<p>Another illustration of the remarkable superiority of the male over +the female, in many parts of the bird world, is seen in the case of +the common barnyard fowl. The rooster is so much more gorgeous than +the hen that anyone reasonably acquainted with these birds cannot have +failed to notice the fact. In some of our modern varieties we have by +breeding colored them nearly alike. The original chicken is<span class="pagenum"><a name="Page_133" id="Page_133">[Pg 133]</a></span> colored +much like the common Leghorns. Shades of red and yellow decorate his +neck and back, while the flight feathers of his wings and of his tail +and the sickle feathers which ornament the rear of his back and hang +over his tail are lustrous dark green. The hen meanwhile is very much +less brilliant in her contrasts. I shall speak more fully of this in +discussing polygamy.</p> + +<p>The attraction of beauty is not the only lure by which a creature may +win its mate. Sound may captivate as effectively as beauty. This is +true of insects as well as of birds. Certain insects at least advise +their mates of their presence by means of a sound which they emit. +This is particularly noticeable among the group of straight-winged +insects to which the grasshopper, katydid and cricket belong. The +grasshopper has a ridge on the angle of his wing and a roughness on +the side of his leg. When these two are rubbed together the result is +sometimes a fiddling, sometimes a snapping or cracking sound, +differing in different grasshoppers. I doubt not these sounds are +pleasing to the female of the species, for they are always made by the +male. The katydid, instead of fiddling in this way, has a sort of drum +on the angle of his one wing, which he can rub over a tooth in the +corresponding angle of his other wing, thus producing the familiar +"katydid" sound. I have never<span class="pagenum"><a name="Page_134" id="Page_134">[Pg 134]</a></span> succeeded in making a dead grasshopper +fiddle, but I have long known how to make a dead katydid say "ka." +Quite recently I have added to my accomplishment in this respect and +can make it say "katy." The "did" part of the song still lies beyond +my power. The crickets produce their sharp notes in much the same +fashion as the katydids.</p> + +<p>One observer of the chirping of the cricket says that the pitch of the +song varies with the temperature. He has even worked out a formula by +which one can tell the pitch of the chirp, if he knows the +temperature, or, knowing the temperature, can determine the pitch. Of +course this is too mechanical; yet it indicates that there must be +considerable relation between the two; the warmer the cricket the +happier he is.</p> + +<p>It is the males among insects that chirp their love songs. The females +never answer them. There is a peculiar notion that the female katydid, +when thus accused of some offense, replies "katy didn't." The truth of +the matter is that no female katydid ever replied to the accusations +of her lover, if accusation it be. She is absolutely dumb, not having +the drum upon her wings with which to reply. She is provided with ears +wherewith to hear, and, strange to say, she keeps them on her elbow, +as does also the cricket,<span class="pagenum"><a name="Page_135" id="Page_135">[Pg 135]</a></span> while the grasshopper has his ears upon the +side of his body.</p> + +<p>Everyone who lives in the country, or goes into the country in the +summertime, is sure to know the humming of the so-called locust. It is +an unfortunate fact that the word locust may have several meanings. It +is properly applied to one group of the grasshoppers. The creature +most commonly called a locust is a cicada, or harvest fly. When the +weather gets quite warm the cicada starts his love song. He has two +long flaps to his vest, and under each flap he has a vibrating drum +head. This is set shivering by a muscle on its under side. The female +cicada again is silent.</p> + +<p>It is among birds that the love song reaches its finest development. +It may consist simply of a little chirp as in the chippy. It may +consist of two notes of a different pitch repeated steadily, as in the +tufted titmouse. It may attain considerable variation, as in the +robin. But in the choir of our best singers, like the catbird, +thrasher, and mocking bird, there is unending variation of notes. It +seems almost impossible to doubt the charming quality of this voice +upon the mate. It certainly is chiefly confined to the mating season, +and is indulged in almost entirely by the males. This does not mean +that a male does not sing excepting when he wishes to charm his mate. +But<span class="pagenum"><a name="Page_136" id="Page_136">[Pg 136]</a></span> the time when he is in his most exquisite feather and most +charming mood is the time when he sings most sweetly, and this is the +time when he is taking to himself a mate. The love joy may so +overcrowd his life that he sings much and often, but the increase in +its amount and character during the mating season seems to proclaim +its purpose beyond a doubt.</p> + +<p>In addition to the allurements above described there are certain +peculiar behaviors of the animal during the mating season which are +intensely interesting. Sometimes they consist simply of a wild +delirium of joy, which overpowers the animal completely and makes him +do wonderful things. Birds will fly with impetuous leaps in the air, +mount higher and higher, singing wildly, only to turn suddenly at the +top of the flight and drop promptly to the ground. I have seen such +ecstatic flights in the oven bird and in our rollicking gold finch. I +have seen a catbird on his way to a tree turn three somersaults, much +like those performed by a tumbler pigeon, after which he alighted upon +the bough. None of these acts seemed deliberately performed in front +of the females, but I have seen three or four killdeer parading in +most stately and precise manner, spreading their wings and fluffing +their feathers, performing a sublimated cup-and-cake walk amid a +circle of attracted females.</p> + +<p>Even our little English sparrow, as I have previ<span class="pagenum"><a name="Page_137" id="Page_137">[Pg 137]</a></span>ously mentioned, +fluffs himself up and spreads his wings and prances around in front of +his presumably adoring ladylove. But the weirdest performance of this +sort I have ever seen is that shown by the male ostrich. When he +becomes excited, swaying his body from side to side, he sinks slowly +upon his knees, until his body touches the ground, his wings spread on +either side and the feathers fluffed up so as to show every exquisite +plume in all its splendid beauty. The long neck is laid back until the +head, which is doubled sharply forward, is pressed almost against the +back, and in this strange position he sways from side to side, +apparently utterly oblivious, for a time, of everything. After about a +minute of this performance, he seems slowly to come to himself and +rise again to his feet. Now he is particularly likely to make vicious +attack upon anything within reach.</p> + +<p>It is not only necessary that the animal should be able to attract a +mate. There may be more than one claimant for the damsel's affection. +In many animals we see provisions whereby the male may effectively +deal with his rivals. This is especially likely to be the case if the +animal be a polygamist. In every species there are produced about as +many males as females. If the polygamous habit leads one male to +gather about him a group of females, with whom he mates, it is evident +that he is displacing an equal num<span class="pagenum"><a name="Page_138" id="Page_138">[Pg 138]</a></span>ber of rivals, and they are not +willingly displaced. Accordingly we find that polygamy is usually +accompanied by a belligerent disposition on the part of the males. In +our ordinary barnyard fowl this trait is very evident. The rooster not +only domineers over the hens, not only struts about among them in +stately fashion and gives vent to his feelings by his sonorous voice, +he must also drive away from the neighborhood any rivals for the +affections of his wives. Hence the rooster attacks upon sight the +neighboring rooster, and battles with him to his entire discomfiture +and sometimes to the death.</p> + +<p>Among the members of the deer family this particular phase of the +relation between the sexes has produced in the males, and only very +rarely in the females, the magnificent branching horns. These are +intended not so much as a protection against the enemy as for an +offensive weapon in the battle for the mates.</p> + +<p>Beautiful and stately as are these magnificent horns, they last only +for a part of the year. We begin to understand their meaning. When the +wolf is hungriest, toward the close of the bitter winter, the deer is +without horns. When the time for mating comes, the deer within a few +weeks grows his horns, which at first are covered with a plushlike +coating, known as velvet. After a while this dries and he rubs his +horns<span class="pagenum"><a name="Page_139" id="Page_139">[Pg 139]</a></span> against the trees until they are clean and smooth. Now he is +ready for the battle royal.</p> + +<p>In the case of the fur seals polygamy has carried its specialization +of the males to a remarkable extent. The bull seals are several times +as large as the cows, and are provided with terrific canine teeth. +With these they battle with a violence that very often results in the +death of one of the combatants. A successful bull seal who has +gathered about him a cluster of seal cows is seamed and scarred with +the marks of his annual combats.</p> + +<p>One more type of adaptation can be profitably considered. Animals have +developed many devices which serve for the protection of their young. +The wonderful silk spun by the spider was evidently primarily intended +to serve as a covering for the eggs. Probably all of our spiders agree +in using the silk for this purpose. Many of them employ it for +practically no other, though there are half a dozen different uses to +which different spiders may put their silk. Under these conditions we +have a right to infer that silk was primarily developed as a coating +for the eggs. In the case of some of our spiders a little fluffy mass +of silk covers the egg, while a firmly woven sheet of silk covers both +egg mass and fluff, holding it flat against a wall or the trunk of a +tree. In some of the higher spiders, notably our bank spiders, the +silken covering<span class="pagenum"><a name="Page_140" id="Page_140">[Pg 140]</a></span> becomes an effective cocoon, spherical in shape, with +a little opening at the top like the neck of a small bottle. The egg +cocoon is woven in a mass of tangled silk between the branches of some +tough weed which will be sure to outlast the winter. Into the egg +cocoon the spider may place one thousand or more eggs. Having thus +provided her children with a snug winter home, the spider dies. When +spring comes with the warm rays of the sun, the eggs hatch and the +cocoon becomes a creeping mass of minute spiders. At the time these +spiders appear there is nothing for them to eat. The obvious way out +of this difficulty is taken. At once there begins a progressive party. +Spider fights with spider, and the prize in each conflict is the body +of the victim, which is promptly eaten. The winners in the first round +pair off again, and a little later, as hunger drives them, another set +of combats comes on, resulting in another halving of the number of +spiders in the cocoon. This process continues until not more than +one-tenth of the original number of spiders remains. By this time they +have gained sufficient strength of leg and jaw, and sufficient +dexterity in the use of both, to make it safe for them to venture out +and try their fortunes among the accidents of a strenuous world. There +can be little doubt after this long process has worked its final +results which tenth remains. Chance plays but small part in this<span class="pagenum"><a name="Page_141" id="Page_141">[Pg 141]</a></span> +game. It is the fittest that survive. When this procedure goes on +generation after generation, the result must necessarily be that the +spiders grow fitter and fitter for their work. This method is hard on +the little spider, but it makes good spiders.</p> + +<p>Most insects die before their eggs hatch; accordingly they can pay no +attention to their own children. Whatever arrangements are provided +for the safety and strength of these offspring must be provided before +they appear. About the only care the majority of insects take in this +direction is to see that the eggs are placed where the young shall +find food as soon as they emerge. Insects' eggs are very small, and as +a consequence the creatures which emerge from them are likewise +exceedingly minute. As a result they cannot be expected to hunt far +for their food. Different insects use different devices by which to +overcome this difficulty. The katydid, for instance, must die with the +approach of fall. Her children will not appear until the following +year. Her food consists of leaves, but to lay the eggs in such a +situation would be a fatal process, because the leaf will drop off +before the eggs hatch. Accordingly, the katydid lays its shield-shaped +eggs in a double row near the end of a young twig. Next year when the +weather is sufficiently warm to hatch katydids, it is also warm enough +to force the buds on the end of the twigs.<span class="pagenum"><a name="Page_142" id="Page_142">[Pg 142]</a></span> When the katydids arrive +their jaws are young and tender, but so are the leaves upon which they +are born. Hence there is little difficulty on the part of the young +katydids in finding an abundance of food. By the time the leaves have +grown tougher, the katydid's jaws are stronger, and the leaves will +still serve as food.</p> + +<p>Everyone who is at all familiar with country life and gardening is +familiar with what is called the potato or tomato worm. It is a long, +green, smooth, caterpillar, as long and as fat as your finger and +provided with a horn upon his tail. The gardener may not know that +after a while this creature will burrow into the ground, and there +change into an oblong brown mass with a sort of a pitcher handle at +one side. Next year this pupa will split down the back, and from out +of the brown case will come a hawk-moth, which soon will fly with +rapidly quivering wings and feast upon the nectar of our moon flowers +or on that of the "Jimson" weed. Those who have cleaned these pests +from the potato or tomato vines will often have noticed one of them +covered with what look almost like grains of rice. This appearance +reveals an interesting story. Some time earlier an insect that looked +very much like a dainty wasp with a rather long sting in its tail +hovered over the caterpillar. This is the ichneumon fly. Eventually +lighting upon the<span class="pagenum"><a name="Page_143" id="Page_143">[Pg 143]</a></span> caterpillar's back, it punctured the skin with its +sting, and deposited eggs within the caterpillar's body. These eggs +soon hatched and the little grubs worked their way through the body of +its host. The infested victim feeds upon leaves and fills itself with +rich food. These parasites eat the food, and, try as it may, the +caterpillar does not succeed in getting fat. After the grubs have +gotten their full growth, each of them eats its way through a little +hole to the outside of the caterpillar's body. Here it spins around +itself a little white case, and looks like a rice grain. As the +caterpillar moves about, these seeming rice grains are rubbed off and +fall to the ground. Next year there will come up new ichneumon flies +to sting fresh caterpillars and repeat the entire process.</p> + +<p>Another remarkable provision for the young on the part of insects is +seen in the behavior of the big sphex wasp, known as the cicada +killer. The cicada, it will be remembered, is what is commonly called +a locust. The cicada killer is a magnificent big wasp, whose body is +nearly an inch long, banded with black and yellow, while the wings are +colored a smoky brown. This muscular wasp digs a long tunnel eight or +ten inches deep, which ends in a slightly larger room. Having provided +the location, he now sallies forth in search of the cicada. The heavy +song of the male probably serves as a guide to the wasp in case<span class="pagenum"><a name="Page_144" id="Page_144">[Pg 144]</a></span> of +scarcity of cicadas, but the killer has apparently little difficulty +in finding his prey. The wasp pounces upon the insect, and in spite of +its strength and the thrashing of its vigorous wings punctures it with +his sting again and again. The poison of the sting entering into the +nerve centers gradually paralyzes, but usually does not kill, the +cicada. Now the killer carries its prey home, pushes it to the bottom +of the tunnel and deposits upon it a single egg. The wasp closes up +the hole and leaves the place. When the egg hatches and the grub of +the wasp emerges, it finds a big cicada just at hand, upon which it +feeds. By the time the cicada is completely devoured, the wasp grub +has obtained its full growth. After a short period of development a +new sphex wasp is ready to work its way out of the tunnel, find a +mate, dig a hole, and safely provide for its own children.</p> + +<p>Still more remarkable adaptations for the care of the young appear +among the birds. Here the eggs are not to be deserted, but are to be +cared for until the young appear. These again must have attention +until such time as they are quite able to take care of themselves. The +birds are warm-blooded animals, and even their young, while they are +developing in the egg, are warm-blooded. Consequently the temperature +of the egg must be maintained evenly and uniformly, or there will be +no development.</p> + +<p><span class="pagenum"><a name="Page_145" id="Page_145">[Pg 145]</a></span>The fish may drop its eggs carelessly upon the bottom of the stream. A +frog may deposit them in a mass of jelly and leave them forever. A +turtle may bury its eggs in a sand bank and abandon them to their +fate. The warm blood of the young bird demands more attention than +this. Accordingly, the parent bird has learned to make for itself some +sort of nest, in which the young may be kept properly warm until they +are developed. The ancestral bird, who was to be the progenitor of the +entire bird class, must have had some very simple method of providing +a place in which its eggs might be hatched. As the descendants of this +original bird have passed into new situations, the various lines have +taken upon themselves different shapes until we have the multiform +birds of to-day. The habits of the birds have also varied. Each has +adapted itself to the situation in which it found itself, and no +adaptation has been more varied and effective than the adjustment of +the nesting site. Nests are found upon the ground, in the bushes, on +the lower limbs, in the crotches of the trees, in the trunks of the +trees, upon their very summits, and on the tops of inaccessible crags. +To every sort of situation some bird has been enabled to adapt itself. +This has made it possible for very many more birds to thrive than +could have found a place in the world, had they all lived upon the +same plan.</p> + +<p><span class="pagenum"><a name="Page_146" id="Page_146">[Pg 146]</a></span>In the case of the bank swallow his nest may be a very simple +contrivance, consisting only of a tunnel running back into a bank, and +widening at the back. Some material that will soften the bed upon +which eggs are to be laid must be placed in this cavity. The whole +home is a very simple and crude affair. But little better is the +arrangement which the woodpecker calls a home. This has been cut into +the dry wood of a defective tree. No woodpecker can make his home in +absolutely solid sapwood. Hence the first labor of the woodpecker must +consist in finding a place in which it can dig. If there is an old +stump of a limb sticking up, the problem is readily solved. Such wood +has no sap in it, and is brittle enough to be easily dug out. But, if +there be no such stub, the woodpecker will find a suitable place in +most trees. At some time or other almost every tree loses a big limb. +When such accident occurs there will always be in the old trunk a +region through which sap once went to this limb. This region, deprived +of its function, goes completely dry, like the heartwood of the tree, +and it is into such material as this that the woodpecker succeeds in +drilling his well-protected home.</p> + +<p>As birds rise higher in the scale the nest-building becomes a more +complicated affair, and after a while we find a well-woven substantial +nest, through which even the air will not chill the eggs enough to +prevent<span class="pagenum"><a name="Page_147" id="Page_147">[Pg 147]</a></span> their hatching, while the warmth is supplied by the mother's +body. It is often a matter of surprise to many people that a bird +should contrive to build a nest so exquisitely circular. The trick, +after all, is not quite so difficult as it looks. The robin gathers up +a few sticks and places them as the beginning of the platform. More +and more are brought and woven into each other, making a framework +altogether too big for the nest. Then mud is brought and plastered +inside of this. With the plastering of this mud the careful +circularity of the work begins. Every time a little material has been +added the robin sits down in the nest and revolves her body, in this +way shaping the interior much as the potter shapes a pot. In the case +of the artisan, it is the pot that revolves. In the case of the robin, +the bird itself revolves. The effect is the same in both cases—a +circular vessel is produced. A little lining added to the interior of +the nest softens it for the reception of the eggs. In this exquisite +home the robin lays her eggs, and sits upon them until they are +developed enough to hatch, and then feeds the young until they are old +enough to feed themselves.</p> + +<p>Far more remarkable than any of the devices thus far described are the +wonderful developments which have come in the class of animals known +as the mammals. Here the most wonderful protection is made<span class="pagenum"><a name="Page_148" id="Page_148">[Pg 148]</a></span> for the +care and feeding of the young. But this is to be the subject of a +separate chapter.</p> + +<p>As long as we thought of each sort of animal as being a separate +species shaped in the beginning by the hands of the Creator, each of +these devices seemed to us a new manifestation of the Divine +Providence, whose fertile planning had conceived so many methods of +providing for his children. Unconsciously we thought of God acting as +man acted. Each animal seemed a purely separate invention purposely +designed for an especial place. Now we understand the plan in creation +better, and see that each animal has come from another not quite like +itself, some distance back, and this from still another. Our +admiration for these devices as they arise through evolution is no +less, but takes on another form.</p> + + + +<div class="section_break"></div> +<p><span class="pagenum"><a name="Page_149" id="Page_149">[Pg 149]</a></span></p> +<h3>CHAPTER VI</h3> + +<p class="chapter_subhead">Life in the Past</p> + + +<p>Anyone who earnestly studies plants and animals as they exist in the +world to-day cannot help wondering how the earth began and where it +got its life. This is the true end and aim of geological study. The +history of man seems to run back into a far distant and gloomy past. +Except for the poetical account in Genesis and the traditions of +various peoples throughout the world, real history fades away into an +earlier time of which there are no written records. When the delvers +in the Mesopotamian plain talk to us of kingdoms running back through +seven or eight or nine thousand years, we seem to be getting back to +the beginnings of things. But seven or eight or nine thousand years +are as nothing in comparison with the age of the earth, which runs +back into a past so limitless that no man can safely assign any set +figure to it. In a recent paper, Dr. Walcott, of the Smithsonian +Institution, says that the antiquity of the earth must be measured not +in millions, for they are too short, nor hundreds of millions, for +this carries us too<span class="pagenum"><a name="Page_150" id="Page_150">[Pg 150]</a></span> far, but must surely be measured in tens of +millions of years.</p> + +<p>When we attempt to study the past we find its various epochs unequally +clear to us. In human history only quite modern times are absolutely +clear. The history of the Middle Ages is distinct enough for us to +build for ourselves a picture of the time with reasonable hope of +gaining a correct view of the state of affairs. Back of this comes the +long stretch of the Dark Ages, in which here and there we have bright +spots, but it will perhaps long be impossible to portray clearly the +life of the people. Getting back to the Romans, things once more +become reasonably plain, as is true also in the case of Greek history. +Back of this stretches the Egyptian with fair precision, and, older +than it, the Babylonian and Chaldean. But these past three have not +left nearly so definite an account for us as did the later +civilizations of Greece and Rome.</p> + +<p>When we try to go back of these we must change our method of study +entirely. Writing is absent, and all we know of earlier men must be +inferred from a few pictures that were daubed on the rocks or carved +in ivory or bone, from tools made of stone or bone, from a few metal +or stone ornaments, or from the bones of the men themselves. Even so, +the history fades out without telling us its own beginnings. It<span class="pagenum"><a name="Page_151" id="Page_151">[Pg 151]</a></span> is +quite as impossible for history to write its origins as it is for man, +from his own knowledge, to describe his birth.</p> + +<p>What is true of the human story is quite as true of that of the earth. +Recent steps are very plain. We may read them with considerable +confidence. As we go deeper into the rocks and find older fossils, the +evidence becomes less certain. The animals differed enough from those +of to-day for us to be less sure what they were like. As we keep on +moving backward through time, and downward through the rocks, we find, +after a while, strata in which there are evidences of life that +existed long ago, but in which these traces are so altered that it is +impossible to tell what sort of living things existed; we learn only +that they were alive. Going back still further, these fade out. There +is no knowing when the earth began; there is no knowing when life +began upon the earth. It is not meant that men have not wondered, even +reckoned carefully, as to how long ago each of these events occurred. +Many speculations have proved entirely useless, a few remain as yet +neither confirmed nor disproved, and of such we shall speak.</p> + +<p>For the last hundred years the theory of the earth's origin suggested +by the Marquis Pierre Simon De La Place, of France, near the end of +the eighteenth century, has held almost undisputed sway among men<span class="pagenum"><a name="Page_152" id="Page_152">[Pg 152]</a></span> who +were willing to consider the question as open to human solution. This +theory is known as La Place's Nebular Hypothesis. When men began to +study the heavenly bodies with the newly invented telescope, new ideas +naturally sprang up. Among the objects which the glass disclosed were +the nebulæ, which are great clouds of fire mist, glowing masses of +gas. They are scarcely visible to the naked eye, but are among the +most interesting objects in the heavens when seen through a telescope. +The other suggestive heavenly body was our sister planet, Saturn. +Besides having a full complement of moons, Saturn has around it, as +distant as we would expect moons to be, three great rings. These look +very much as if one's hat, with an enormously wide brim, should have +the connection between the rim and the hat broken out completely, but +the rim should still float around the hat without touching it and +should steadily revolve as it stood there. The rings of Saturn are not +solid like the suggested hat rim. They are evidently made up of a +great number of very small particles, each moving around the center of +Saturn. But the great cloud of them is spread out flat. At the +distance which Saturn is from the earth they look as if they made a +solid sheet. Furthermore, they do not form, as it were, one continuous +hat rim, but it is as if the rim were broken into three circular +sections, each bigger than<span class="pagenum"><a name="Page_153" id="Page_153">[Pg 153]</a></span> the one inside it and separated from the +next by an area nearly as wide as the ring itself.</p> + +<p>With such material in the heavens to guide him, La Place suggested +that the sun had once been an enormous fire mist scattered over an +area billions of miles in diameter. This gaseous material, by the +attraction of its particles for each other, began to condense and +contract. When the plug is pulled from a washbasin the particles of +water, in moving toward the center, in order to get out of the basin, +invariably set up a rotary motion. As the particles of this diffused +nebula began to gather together they, too, gave to the mass a rotary +movement. This grew more and more rapid, with greater contraction, +until the particles on the outer edge of the rotating mass had just so +much speed that the least bit more would make them tend to fly off as +mud would fly from a revolving wheel. When this point was reached +there was a balance of forces which made the outermost portion remain +as a ring while the rest contracted away from it, leaving it behind.</p> + +<p>It was La Place's idea that this process had repeated itself, and ring +after ring had been left behind. Finally the sun condensed and grew +into a ball, occupying the center of the system. At varying distances +from it were to be found either rings or planets which had been formed +out of such rings. For La<span class="pagenum"><a name="Page_154" id="Page_154">[Pg 154]</a></span> Place suggested that in a ring like this +the material could not be quite evenly distributed. While every +particle in the ring kept revolving around the sun, those in front of +the densest part were slowly held back by the attraction of the +thicker portion, while those behind it in rotation had their speed +hastened until finally all the material in the ring had collected at +one spot and a new planet was born. La Place believed that these +planets formed their moons in exactly the same way, and that Saturn +was simply a planet not all of whose moons had yet been formed. He +believed that this happy accident served to tell us how the universe +had been created.</p> + +<p>Of course, so detailed a theory concerning anything of which we know +so little has always had much ridicule thrown upon it, and yet no +truly competing theory has been proposed until very recent times.</p> + +<p>Within a few years a Planetesimal Theory has been announced, and is +gaining considerable prominence, although it is too early yet to say +whether it will supersede La Place's idea. In this theory, also, the +suggestion comes from the heavenly bodies. With the increasing study +of the nebulæ, many forms of these interesting bodies have been +discovered. A very common type consists of a great coherent central +mass, with two or more arms extending from opposite sides in the form +of a spiral. This is as if gaseous re<span class="pagenum"><a name="Page_155" id="Page_155">[Pg 155]</a></span>volving nebulæ had come into +comparatively close proximity to a passing body. The visitor, by its +attraction, drew from the nebula a wisp of gas. The revolving motion +of the nebula gave to the attracted arm the spiral form.</p> + +<p>These twisted arms are not equally dense throughout, but have +thickened knots here and there in their course. The Planetesimal +Theory suggests that these thickened knots are embryo planets and the +central portion of the nebulæ an embryo sun. After all the material in +such a body has condensed either around the knots or about the central +mass a new solar system will be complete. As before stated, neither of +these theories can be said to be demonstrated. Each of them has points +in its favor and each has its difficulties. It is pleasant to know +what men have clearly thought concerning such questions, but for a man +not a trained geologist neither will carry much conviction. He will +still rest with his own early conclusion that whichever shall prove to +be true, for him his old formula is still valid, "in the beginning God +made the heavens and the earth." He will no longer think of God as +having shaped the balls with his own hand and thrown them into space; +he will no longer dream that it all occurred within a week not more +than six thousand years ago; but still to him will come the reverent +conviction that, whatever the plan by which<span class="pagenum"><a name="Page_156" id="Page_156">[Pg 156]</a></span> it was accomplished, it +was still God's plan and God carried it out.</p> + +<p>Now that we have tried to stretch our imagination back to the origin +of our globe, the question not unnaturally comes to our mind, how long +ago did all this happen? Is there any possible means of telling when +the history of the earth began? All such attempts lead either to +indefinite or to uncertain conclusions. Each man who essays the +problem approaches it from a different side and ends with a different +result. But no matter what the method of approach, all are agreed on +at least one point, the enormous length of time, as counted in years, +through which the earth has lasted.</p> + +<p>One great mathematician worked on the basis of the rate of the present +cooling of the earth. Counting backward to the time when the earth's +surface must have been hotter, according to La Place's idea, he +decided that our globe has been cool enough for the existence of life +upon it for a period of somewhere in the neighborhood of one hundred +million years. Those who try to study the rate at which mud is being +deposited in our bays and at the mouth of our rivers, and who hence +try to deduce how long it has taken to produce the thickness of all +the stratified rock we know, arrive at a figure larger, rather than +smaller, than that mentioned above. The same is true of those who try +to count the age of the earth by the rate at<span class="pagenum"><a name="Page_157" id="Page_157">[Pg 157]</a></span> which the present rivers +are carrying away their river basins, and hence who calculate how long +it has taken the rivers of the globe to wash away all the rocks which +it is quite clear have been carried out. Still others have attempted +to solve the problem by seeing how much salt the rivers are carrying +into the sea, and consequently how long it must have taken the sea to +become as salt as it is. A very late attempt has been based on the +alteration in the minerals that show radio-activity. Conservative +estimates, based on all of these, would give us a figure on which we +must not count with any exactness, but which will serve at least to +mark the present trend of opinion. We may put this figure at one +hundred millions of years.</p> + +<p>The following <a href="#geological_times">table</a> gives us the names of the periods into which the +geologist has divided the past history of the earth. The first column +gives a simple name, which, in each case, is a translation of the +technical name the geologist gives to the era. This technical name is +also given in parenthesis. The second column shows the number of years +ago at which this period may be placed, while the third column gives a +series of names most of which are in use in geology and which are +intended to indicate the stage of advancement of the higher animals in +that particular period. Some of these names are perhaps giving way to +later terms, but all of them will be understood by<span class="pagenum"><a name="Page_158" id="Page_158">[Pg 158]</a></span> any geologist. +Most of them will serve to keep very clearly before the mind of the +ungeological the period which he is studying. Like all such tables, +this must be read from the bottom up. This arrangement is used because +the oldest rocks in the series are naturally at the bottom and the +newest rocks are on the top, though occasionally a region is +sufficiently upset partly to reverse the order.</p> + +<div id="geological"> +<p class="caption"><a name="geological_times" id="geological_times"></a>TABLE OF GEOLOGICAL TIMES</p> + +<table summary="Table of geological times"> +<thead> +<tr> + <th class="table_cell_3110">ERAS</th> + <th class="table_cell_3111">MILLIONS OF YEARS AGO<br />(VERY UNCERTAIN)</th> + <th class="table_cell_3011">STAGES OF ANIMAL DEVELOPMENT</th> +</tr> +</thead> +<tbody> +<tr> + <td class="table_cell_1110">Recent Life (Cenozoic)</td> + <td class="table_center table_cell_1111">0 to 5</td> + <td class="table_cell_1011">Age of Man (Quaternary)<br />Age of Mammals (Tertiary)</td> +</tr> +<tr> + <td class="table_cell_1110">Middle Life (Mesozoic)</td> + <td class="table_center table_cell_1111">5 to 10</td> + <td class="table_cell_1011">Age of Reptiles</td> +</tr> +<tr> + <td class="table_cell_1110">Ancient Life (Palæozoic)</td> + <td class="table_center table_cell_1111">10 to 25</td> + <td class="table_cell_1011">Age of Amphibians (Carboniferous)<br />Age of Fishes (Devonian)<br />Age of Invertebrates (Silurian and Cambrian)</td> +</tr> +<tr> + <td class="table_cell_1110">Dawn Life (Eozoic)</td> + <td class="table_center table_cell_1111">25 to 50</td> + <td class="table_cell_1011">Earliest Animals and Plants</td> +</tr> +</tbody> +</table> +</div> + +<p>Having seen what the scientist supposes to be the method of formation +of the earth itself, it will be<span class="pagenum"><a name="Page_159" id="Page_159">[Pg 159]</a></span> interesting next to consider what the +biologist surmises as to the origin of the life upon the earth. Here +again two explanations hold. The one, and distinctly the older of the +two, says that at some time in the far distant past, under conditions +which are rarely if ever duplicated, out of the lifeless material of +the globe were produced simple and low forms of life. These could not +properly be called either animal or plant, but partook somewhat of the +nature of both. Of this there is at present no evidence whatever. The +only reason we have for suggesting it is that, if we understand the +past conditions on the earth, there was a time when life was +impossible. Now we find life. Hence it must have arisen. This of +itself, of course, furnishes no proof, but leads us to try to imagine +how the transition might have come about. Every scientist who believes +in this form of origin holds that if the exact conditions are repeated +the result will occur once more. He may believe that no such +repetition is possible, but he is confident that, if it could be, life +would arise again from lifeless matter.</p> + +<p>This process of life arising from matter that is not alive is known as +Spontaneous Generation. Two hundred years ago it was supposed to occur +frequently. It was common belief that the beautiful pickerel weed +which borders our Northern lakes, after freezing, went into a sort of +protoplasmic slime out of which pick<span class="pagenum"><a name="Page_160" id="Page_160">[Pg 160]</a></span>erel were produced. The eelgrass +of the river was supposed to yield eels in a similar fashion. The dead +bodies of animals were supposed to turn into maggots. Such crude ideas +of spontaneous generation are no longer possible. The whole science of +bacteriology absolutely presupposes the impossibility of spontaneous +generation in the flasks and test tubes of the laboratory. One or two +men of otherwise good standing in science still maintain that they are +getting new life in their own test tubes, but they fail utterly to +persuade the scientific world. I think it is a fair statement of the +position of science to-day to say that there is no evidence whatever +of spontaneous generation, excepting the presence of life upon the +globe.</p> + +<p>Not all has been said, however, on this question. The chemist is +learning in the laboratory to produce many substances which, until +very recent times, were produced only in the bodies of animals or +plants. Dye-stuffs were originally gotten almost entirely from animal +or plant material. At present the great majority of them are made in +the laboratory, and in not a few cases they not only imitate the color +of the older material, but actually have identically the same +composition and constitution. The laboratory-made material is exactly +like that made by the animals or the plants.</p> + +<p>The same is true with regard to a large number of<span class="pagenum"><a name="Page_161" id="Page_161">[Pg 161]</a></span> the fruit flavors. +These are due to the presence of ethereal oils in the plant, and their +exact counterparts can now be produced in the laboratory, and can +serve every purpose of the fruit flavor itself. Alcohol has been +produced artificially, and alcohols, which nature never dreamed of +making, so far as we can tell, but which are made on her plan, are +manufactured by the chemist. Last of all, sugar has recently been +built up by the chemist, though the method at present is so expensive +that it cannot possibly compete with the production of the commodity +from the cane and the beet. As in the case of alcohol, all the sugars +that nature makes can now be made artificially, and others of the same +general plan which she seems not to have as yet devised can be +produced within the laboratory.</p> + +<p>Attempts have been made to manufacture proteids, but these have as yet +eluded the efforts of the chemist. He is beginning, however, to come +nearer understanding their composition, and when he once clearly +comprehends that he may be able to reproduce them.</p> + +<p>One of the German chemists is convinced that the nuclein in the +nucleus of the cell is not a very complicated compound. Under such +conditions it is not a matter of surprise that the physiological +chemist should be constantly dreaming that he may at some time produce +living matter in the laboratory. To the ordinary mind it scarcely +seems possible. We are so<span class="pagenum"><a name="Page_162" id="Page_162">[Pg 162]</a></span> entirely sure that life is not amenable to +physics or chemistry that we can hardly conceive of the possibility of +its originating out of matter in the test tube. If it does so come, +and when it does so come, this will not prove that life is a less +noble and less wonderful thing than we thought. It will only prove +that chemistry and physics are more noble and more wonderful than we +dreamed.</p> + +<p>There is another way of approaching this life problem, though it seems +to be rather a begging of the question than a solution of it. Of +recent years it has been discovered that even the very low +temperatures obtained by evaporating liquid air, say three hundred +degrees below zero, Fahrenheit, do not kill seeds or spores of mold. +The space between the planets is undoubtedly extremely cold. We have +always supposed it to be entirely too cold for life to exist in it. +But we laid little stress on the fact because we had no thought of any +possible life existing there. But the discovery that seeds and spores +can live uninjured through extreme cold has led to an interesting +suggestion. This is that when the earth became adapted to the presence +of life it was infected by germs transported on meteors from some +other system. According to this theory, organic dust through space is +ready to infect any planet which offers the conditions under which +life may arise. Of course this theory does not<span class="pagenum"><a name="Page_163" id="Page_163">[Pg 163]</a></span> explain the origin of +life. It pushes back that origin a little farther or supposes that +life is as old as matter itself. Again we may leave to the scientist +the discussion and the elaboration of this or any other theory he may +promulgate concerning the origin of life. When he has established +clearly the process and can produce life we will accept his +explanation; meanwhile, we will always be interested in his attempts +to solve the problem, but still our simple formula, "in the beginning +God," serves our present needs and will satisfy us better than any as +yet unverified hypothesis.</p> + +<p>When we find through scientific investigation how life arises we will +simply know how God created it in the beginning.</p> + +<p>The next step in the understanding of early life is to study under the +microscope the simplest forms which we can find in existence to-day. +This, while far easier of execution than the problems which we have +thus far considered, is still not without serious difficulties. But +every day brings us nearer to the understanding of the structure of +living things. Life the scientist cannot see. All he can study is +living matter. Whether life can exist separate from living things is a +problem outside the range of his, at least present, possibilities. +Therefore, concerning it he has no answer whatever to give. But when +we come to study living things we find that all life is associated<span class="pagenum"><a name="Page_164" id="Page_164">[Pg 164]</a></span> +with protoplasm. This apparently foamy, jellylike, transparent +material is the only living substance in all the world. Animals and +plants are larger or smaller collections of the little masses of +protoplasm which we know as cells. The lowest animals are each made up +of but a single cell. This consists of a small mass of protoplasm +surrounded almost always by a thicker skin or covering, known as the +cell wall and enclosing a complicated kernel known as the nucleus. The +protoplasm seems to be the living substance itself. The cell wall is +not a simple dead scum on the outside of the protoplasm, but is itself +able to do certain things which can only, so far as we know, be done +by living substances. For instance, of two materials dissolved in the +water in which the cell floats, the wall may permit one to soak into +the animal and keep the other out. The one allowed to enter will +usually be found good to be used for food by the cell. The nucleus +seems to store within itself the record of its past history and thus +enable the cell to do in the future what its ancestors did in the +past.</p> + +<p>Such simple cells can exhibit in very low form all the activities the +higher animals show in much more elaborate development. A one-celled +animal can move about, can recognize the proximity of food, can engulf +its food and digest it, can build up its own substance out of the +digested food, can absorb oxygen,<span class="pagenum"><a name="Page_165" id="Page_165">[Pg 165]</a></span> can use this oxygen in the burning +of its own substance to produce its own activities, can act in +response to sensation gained from outside, can throw off its waste +matter produced by its own activities, and can grow. When the proper +time comes its nucleus can split in two, the cell itself enclosing the +nucleus can separate into two cells, each of which can grow to the +size of the parent cell and repeat its life. This is as simple an +animal as we have yet discovered. Every kitchen drain swarms with such +creatures. On a summer day the stagnant pools are full of them. The +simplest microscope will show them clearly. This is life in its lowest +terms with which we are acquainted. With such life, it seems to us, +the animal and plant world must have started their existence, when +first the earth began to teem with living matter.</p> + +<p>If, then, we may form any judgment concerning the first living things +upon the globe by considering the simplest creatures that live here +to-day, certain facts seem clear. In the first place, life began in +the water, and for a long time was only to be found in the water. +Single cells are so small and dry out so easily that it is necessary +to their existence that they should be kept entirely moist by the +presence of water all about them. It is true many of them will stand +drying, but while they are thus dried they can scarcely be said to be +much more than just alive. They are utterly in<span class="pagenum"><a name="Page_166" id="Page_166">[Pg 166]</a></span>active, or, as we say, +they are dormant. In such conditions they become covered with a tough +skin, almost a shell, and their protoplasm is itself nearly dry. Under +these circumstances the life processes hardly continue at all. The +protozoa, as these small animals are called, tolerate drought for a +time; but they only live, in any sense worth calling living, when +water is abundant and is neither very warm nor very cold. It is safe +to say that the early life of the world formed in the oceans of the +time. So absolutely is the habit fixed upon cells of protoplasm that +even to-day the activities of the cells of higher animals depend upon +the presence of moisture. The cells of our own bodies are to-day +living, as it were, in an ocean. Everyone can remember far enough back +to recall some time at which a tear slipped from his own eye onto his +own tongue; we know our tears are salt. The tongue has tasted, +undoubtedly, the perspiration from the lip on more than one summer +day; this perspiration tasted as salt as the tear itself. The lymph +that constitutes the "water" of a so-called "water blister" is also +salty, and even the little blood one gets into his mouth in trying +nature's method of stanching the flow from a cut finger gives the +impression that it contains a little salt. Every fluid of the body is +salty, and every cell of the body is bathed in salt water. It is too +long since the ancestors of our cells swam in the seas of the<span class="pagenum"><a name="Page_167" id="Page_167">[Pg 167]</a></span> Eozoic +time for us to assert with any positiveness that the ancestral habit +is responsible for this trait in the descendants. Sure it is that +to-day our cells, like their ancestors of old, live in water, and this +water is slightly salty—as were probably the Archæan seas.</p> + +<p>The geologist tries as best he may to build up the geography of the +earth in the past. He endeavors to judge from the rocks as he now +finds them, where the seas, the bays, the dry land, and the mountains +of earlier geological times lay. The present aspect of the earth is +very recent, and earlier ages must have shown an entirely different +distribution of land and water. The North American continent was +certainly very much smaller than it is now. The first known lands lay +close to the Atlantic seaboard and probably extended out into the +water some distance beyond the present shoreline. The stretch of +continent was narrow, and grew narrower as it went southward. In what +is now the Canadian district, a considerable expanse probably existed +in very early times. Then a great internal sea, shallower than the +Atlantic, stretched its unbroken sheet over almost the entire area now +occupied by the United States, while only a comparatively small hump +of earth, ending in a narrower strip, lay where the great Western +plateau now rears its enormous bulk.</p> + +<p>A large portion of the history of the North Amer<span class="pagenum"><a name="Page_168" id="Page_168">[Pg 168]</a></span>ican continent, with +its developing animals and plants, is tied up with the gradual +shrinkage of this interior sea. Slowly across the Canadian district, +the Eastern and Western lands became connected with each other, while +the waters progressively were pushed down the continent, which was +steadily growing from the east and from the north, though less slowly +from the west, into this internal sea. To-day only the Gulf of Mexico +remains as evidence of the broad stretch that once extended through to +the Arctic Ocean and west beyond the present position of the Rocky +Mountains.</p> + +<p>How this great Eastern backbone of the continent was produced, what +sort of animals lived while these rocks were being formed, or whether +this preceded entirely the existence of life upon the earth, no man +to-day may surely say. In the oldest of the rocks there are beds of +graphite, from which lead pencils are made. This substance is believed +by the geologists to be, like coal, the remains of vegetable life. But +these early rocks have been so heated and baked, so twisted and bent, +that whatever forms of life they once held are now obliterated, or so +altered as to give us no idea of what may have been their character.</p> + +<p>So far as anyone can now see, this past history is wiped out forever +and it will be impossible for men ever to demonstrate the character of +this early life. Speculations, more or less certain, will arise. They<span class="pagenum"><a name="Page_169" id="Page_169">[Pg 169]</a></span> +may, after a while, seem so clear as to receive the acceptance of the +scientific mind. Yet the truth remains that the early history of the +earth, so far as animals and plants are concerned, is probably lost +forever.</p> + +<p>The most striking feature concerning the earliest layers of rocks in +which good fossils are found abundantly is the complexity of the life. +With the exception of the backboned animals, every important branch of +the animal kingdom is represented, and it is just possible that we +have even earlier forms of the vertebrates themselves. This, to the +evolutionist, is very disconcerting. To find the great groups all well +developed at least twenty-five million years ago and to find only +fossils built on the same lines since almost nonplusses him. When the +geologist tells him what an enormous length of time preceded the rocks +in which he finds these fossils and how absolutely these earlier +strata have been altered by the later geological activities he easily +understands why it is impossible to find fossils in them. As a +consequence, the evolutionist is forced to believe that all the +earliest animals have left no clear traces behind them. Life as he +first surely knows it is already extremely varied and quite well +developed in some of its groups. The early animals were as well +adapted to the times in which they lived as are the great majority of +the ani<span class="pagenum"><a name="Page_170" id="Page_170">[Pg 170]</a></span>mals of to-day. The reader must not infer this to mean that +the animals of those days were like our present animals. They were +not. No one traveling in a far country could find there animals as +strange to him as would be those of the earlier stratified rocks. In +these there were no fishes as we know them to-day, not a single member +of the frog and salamander class, not a reptile, not a bird, not a +mammal, and probably no air-living insects. It is highly doubtful +whether there was any animal living upon the land and breathing the +air twenty-five million years ago.</p> + +<p>We start our study, then, at the period known as the Palæozoic era, +the era of the ancient life of the globe, beginning twenty-five +million and ending ten million years ago. The first of the three +sections into which this period of life is divided is known as the +Silurian age, the age of invertebrates. The word invertebrate is an +unscientific but convenient term under which we embrace all the +animals below those having backbones. This period is called the age of +invertebrates because, although there is an enormous wealth of animal +and plant life in the Silurian, there are no backboned animals except +the lowest kinds of fishes. It was supposed for a long time that even +fishes were absent. Now we know they existed, but they were small and +inconspicuous. In this period corals were wonderfully abundant, +particularly in the great inter<span class="pagenum"><a name="Page_171" id="Page_171">[Pg 171]</a></span>nal sea which spread over what is now +known as the Mississippi Valley. Everywhere over this region must have +grown in the shallow water great numbers of creatures called crinoids +or stone lilies. They were attached to the bottom by slender stems, +sometimes many feet long. These stems are jointed, and when they +became fossilized the sections were apt to separate, with the result +that over a wide area in the Mississippi Valley it is very common to +find these little segments which look not unlike checkers. At the end +of the stem was a rounded head, with a mouth at the top, and around +the mouth were branched, feathery arms. The creatures must have been +exquisitely beautiful, but they have completely disappeared from the +face of the earth, with the exception of a very few, found in the +obscurity of the almost fathomless depths of the great ocean. Here +they remain as peculiar relics, only preserved by the unvarying +conditions in the deep sea from the extinction that has met their +sisters.</p> + +<p>Those who are familiar with our seacoast will know an interesting +creature known as the horseshoe crab, or king crab, though in reality +it is not a crab at all. It is rather more nearly related to the +spiders than the crabs, though no one but a technical zoölogist could +possibly associate them together. The ancestors of these king crabs +were the finest and best developed<span class="pagenum"><a name="Page_172" id="Page_172">[Pg 172]</a></span> animals in this early Palæozoic +time. These creatures had bodies jointed like the tail of a lobster. +They were wide and flat, instead of narrow and rounded like a lobster, +and each joint of the body was highest in the middle and distinctly +lower at the two sides, thus forming three regions along their backs. +This structure gives to these creatures the name of trilobites. These +animals were the kings of the early ocean. They had an interesting +habit of curling up nose to tail before they died, and, as a result, a +large proportion of all the trilobite fossils we find are curled in +this peculiar manner.</p> + +<p>After these forms the most abundant fossils we find in Silurian times +were creatures that at first sight looked as if they might be related +to the clams. These are known as lampshells, because one shell +projects beyond the other and curls up at the tip so as to resemble +the clay lamps which are dug out of old Roman towns. The lampshells +also have nearly disappeared in modern times. Simple creatures +belonging with our present crab and snail had begun to make their +appearance, but they were not as abundant as we find them later on.</p> + +<p>The third group of the mollusks to which the nautilus and squid of +to-day belong is very abundantly represented in the Silurian by +fossils with coiled-up shells. As for the plant life of the time, it +is exceed<span class="pagenum"><a name="Page_173" id="Page_173">[Pg 173]</a></span>ingly difficult to say much about it. There must have been +nothing but marine plants, and these must have been on the general +line of the seaweeds. Little can be definitely said concerning them.</p> + +<p>The next period of the Palæozoic is known as the Devonian age, or the +age of fishes. Now the backboned animals first make their clear and +unmistakable appearance. There are remains in the Silurian which show +that there must have been a few fishes at that time. The Devonian is +so full of them and they are so well developed and so diversified that +this period is definitely known as the "age of fishes." They do not +closely resemble the fishes of to-day, but anyone would recognize most +of them for what they are. Their bodies were covered, not so much with +scales as with heavy plates, often arranged like tiles, those on the +forward half of the animal being often larger than those surrounding +the rest of the body. The creature was encased, as it were, in armor. +These were the rulers of the Devonian seas. The land, as yet, was +probably nearly without animal life, the creatures thus far being +almost confined to the water. A few insects make their appearance and +a few thousand-leggers are running around among the lowly plants; a +few spider-like animals have arisen; there are a few snails that have +left the water and taken to the land. Altogether only the dawn of a +land<span class="pagenum"><a name="Page_174" id="Page_174">[Pg 174]</a></span> fauna is to be noticed. In the Devonian the plants are creeping +up upon the ground. Ferns are growing about everywhere, though they +are not exactly our ferns, but are rather a sort of intermediate form +between these and the present seed plants.</p> + +<p>Now comes an entire change in the history of the world. By some means +a rise in the bottom seems to have cut off a great part of the +internal sea from the outer ocean and to have converted it into a +widespread shallow bay, much like the sounds which lie back of the +islands that line the Atlantic Coast from New Jersey to Florida. Just +as this coastal region to-day is covered with salt marshes, so the +whole internal sea of the Carboniferous period was converted into a +great swamp. Sometimes an oscillation of the crust of the earth +brought this marsh above the surface of the sea and a luxuriant growth +of plants spread over it. Then a sinking of the bottom allowed the mud +and sand to wash down the shores, and spread out over the marsh, and +enclose the muck of the marsh under a layer of sand or clay. Another +lift of the bottom would start the swamp growing once more, and a +series of alternations between marsh land and sound seems to have +followed. The plants of this period are not the plants of to-day, +though we still have some very degenerate representatives of them. The +common horse-tail, with its angular,<span class="pagenum"><a name="Page_175" id="Page_175">[Pg 175]</a></span> slender, leaflike branches and +its club-shaped spore-bearing body, is a modern degenerate descendant +of the treelike calamites of the Carboniferous forest. A creeping +evergreen, known by the name of clubmoss, is in like manner the modern +degenerate remnant of the scalestem and sealstem, which were the great +trees of the forests of the coal period.</p> + +<p>All over the surface of the marsh, between these big trees, grew the +ferns. While the coal itself was formed generally from the scalestems +and sealstems, the most common fossils found in the shales that lie +upon the coal beds are the ferns which covered the surface of the +marsh.</p> + +<p>It is believed by many geologists that this great luxuriant forest +points to a time when the climate was far warmer than it is to-day, +when the air was moist and heavily laden with carbon dioxide, and when +a great mass of clouds practically enveloped the earth. In this way +only do most geologists account for the enormous wealth of vegetation +in the Carboniferous period and for the abundance of plants up to the +Arctic Ocean, of the kinds that now grow chiefly in the tropics. But +of recent years a few geologists point to the fact that the peat bogs +of to-day, which seem to be the beginnings of future coal deposits, +are found almost entirely in cold countries. Hence it is a serious +matter to attempt to describe<span class="pagenum"><a name="Page_176" id="Page_176">[Pg 176]</a></span> the climate of any part of the +Palæozoic era. Certainly of the climate earlier than the Carboniferous +it is very risky to say anything definite.</p> + +<p>The forests of the coal period seem actually to have cleared the air; +at least now we begin to find creatures related to our salamanders and +frogs moving about among the stumps of the marshes. These amphibians +are evidently the descendants of some of the fishes of the Devonian +times. Among these fishes were some which bear a great resemblance to +a few found in South America, in Africa and Australia to-day, and +which we know as lungfish. Anyone who has cleaned our fresh water +fishes in preparation for the table will remember that inside of them +there is a long slender bladder filled with air. This bladder assists +in making the fish light, hence making it easier for it to support +itself in the water. In certain swampy regions these lungfish swim +freely in the water of the marshes. When the dry season comes, +however, the water evaporates, draining the marshes completely. This +would prove the death of most fishes. The lungfish have a curious +habit which keeps them over the dry season. They cover themselves with +a coat of mud, inside of which there is a lining of slime produced +from their bodies. In such cocoon-like cases they survive the drought. +The means by which they breathe during this dry season is +inter<span class="pagenum"><a name="Page_177" id="Page_177">[Pg 177]</a></span>esting. The swim-bladder which we have just described in other +fishes is, with this lungfish, peculiarly spongy in its walls, +presenting a large surface full of blood vessels which absorb the air +on the inside of the bladder. This air the fish changes with moderate +frequency, the result being that the swim-bladder serves him exactly +as the lung serves a higher animal. To this fact he owes his name of +lungfish.</p> + +<p>We sometimes gain much light concerning the past history of any +particular form of animal by studying the development of that animal +in the egg, or, in the case of the mammals, before birth. It is an +interesting fact that when the lung begins to form in the embryo it +starts as a simple sac which is an offspring from the gullet, and +occupies the position of the swim-bladder of the fish. This sac later +divides into two, and develops into the lungs of the animal. This +assures the zoölogist that the origin of the lungs in the higher +animals is found in the swim-bladder of the so-called lungfish. In +this Silurian time certain of these lungfish were perhaps trapped in +the basin in the marsh by the uplifting of the border. The waters +becoming progressively shallower and more crowded, these fishes took +to the land, their fins developing into awkward limbs which slowly +became more perfect.</p> + +<p>To state the fact in this simple fashion is to make it seem far less +probable than is really the case. The<span class="pagenum"><a name="Page_178" id="Page_178">[Pg 178]</a></span> simple forms of the life of +lowly creatures, as well as the simple character of the legs and feet +in the salamander class, make the explanation not so unlikely as would +at first sight appear. Suffice it to say that the scientist now +believes that out of the lungfish of the Devonian came the amphibians +of the Carboniferous period.</p> + +<p>At the end of the coal period came the greatest change the face of the +globe had seen for many millions of years. Slowly the continent rose +on both sides of the old interior sea. A great plateau formed in the +region of the Alleghenies and another in the western district, though +this latter uplift was to be completely washed away, and later to rise +again into the Rocky Mountains and the Sierras. With the uplift at the +edges of the continent came a steady rise of the internal marshes, +until what had previously been swamp land became progressively first +dry land and, in the western part, even desert, in that respect being +somewhat like what it is now.</p> + +<p>The amphibians of to-day (animals like the salamander and frog) all +lay their eggs in the water and their young have a tadpole stage. This +doubtless was true of the amphibians of the coal period. With the +beginning of the Mesozoic, or "middle life" period, a change and a +progression comes over the animal world. The tadpole life of the frog +is a rather<span class="pagenum"><a name="Page_179" id="Page_179">[Pg 179]</a></span> lengthened one, while the toad has learned to crowd its +tadpole life within a few weeks. It would seem as if, in the earlier +times of the Mesozoic, this same change of habit had been going on. +With the drying up of the swamp, some of the amphibians crowded their +tadpole stage further and further back, until it was completely +accomplished before their young left the egg. An examination of the +development of the reptile in the egg will show a stage very similar +to the fish and to the amphibians, but this is all experienced before +the reptile emerges from the egg. The reptilian egg, unlike that of +the frog, is covered with a shell, packed away under the surface of +the ground, and left to its own fate. If, as most geologists believe, +the climate of the Mesozoic was distinctly warm, this habit of the +parent of forsaking the egg was not a serious matter. However the +creatures arose, it is certain that in this Mesozoic age reptiles +roamed the forests, swam the seas, and even flew in the air. Probably +at no other time in the earth's history has any one class of animals +so completely dominated the situation as did the reptiles of this age. +They were not only abundant; they were frequently enormously large. +Their skeletons are among the most interesting that we find to-day. +Gigantic lizards, seventy feet long and eighteen feet high at the +shoulders, dragged their heavy bodies through the marshy edges of the<span class="pagenum"><a name="Page_180" id="Page_180">[Pg 180]</a></span> +lakes. Out upon the land others, not quite so heavy nor so large, +roamed about, some of them feeding upon the soft vegetation, others +having teeth fitted to tear down their herbivorous cousins. In some of +them the hind legs and tail were very heavy and the front legs so +light that it is quite clear they must have hopped around as do the +kangaroos to-day. Others of these reptiles went back to the sea, lost +the leglike development of their limbs and regained the flipper form, +though the bones of the fingers and toes are singularly +distinguishable in the paddle.</p> + +<p>Strangest of all, a considerable group of these wonderful reptiles +lengthened their little fingers, sometimes to three or four feet in +length, and had a skin stretched from these fingers over to the body +in such a fashion as to give them wings not unlike those of the bat. +In the wing of the bat, however, four of the fingers of the hand run +through the membrane and support it. In the pterodactyl, as these +flying reptiles are called, the middle finger supports the web, while +the remaining fingers can still be used to clasp objects or serve the +animal to lift himself, as the bat can do with his thumbs.</p> + +<p>Meanwhile an entire change is coming over the plant world. The last +third of this age of reptiles is known as the Cretaceous or chalk +period. Now, for the first time, the forests begin to take on more of<span class="pagenum"><a name="Page_181" id="Page_181">[Pg 181]</a></span> +the character of our forests of to-day. Plants like our willow and +beech, poplar and sassafras appear in great abundance. Their broad +leaves serve better than those of any earlier plants to catch the +sunlight. But in addition they offered such effective evaporating +surface that they cast off rapidly the moisture obtained from the +ground by the plant. Accordingly in the winter season, when the water +in the ground is frozen and not available for plant purposes, they +were forced to throw away their leaves. It is quite possible that up +to and including the time of the Carboniferous, plants were all +evergreen. There had been before this little variation in climate over +the globe. Life in the Cretaceous begins to take on distinctly its +modern form.</p> + +<p>Among the reptiles of the forest there appear to have been a few small +creatures which to an observer of those times, if there could have +been an observer, would have seemed of the utmost insignificance +compared with their giant cousins.</p> + +<p>These little creatures climbed up into the trees to escape their +enemies. There were some in whom the skin, in front of the elbow and +behind the wrist, was loose, and stretched across the joint a little +like the wing of a bat. This reptile, climbing into the trees to +escape its enemies, found that this loose flap of skin served it +nicely, and sailed out of the trees<span class="pagenum"><a name="Page_182" id="Page_182">[Pg 182]</a></span> in a manner not unlike that of +the flying squirrel of to-day. Among these experimenters in aviation, +certain forms produced scales which became elongated and finally slit +up along the side. These slit scales slowly developed into the +feathers of the birds of to-day. Whether the steps by which the change +occurred have been correctly stated or not, the result is sure. In the +rocks of the chalk period we find the remains of an interesting +creature. If nothing but its bones had been found it would have been +called a reptile. It had a long tail, it had claws on its front limbs; +it had teeth in its mouth; it had a flexible backbone. All of these +are reptilian rather than bird characters. Yet on the rocks +surrounding these bones are the unmistakable impressions of the +feathers of the wings and of the tail. Nothing in the world to-day has +feathers excepting the birds, and in this "ancient winged thing," for +this is the significance of its name—archæopteryx—we have perhaps +the most remarkable link in the world between two distinct sections of +the animal kingdom. Here is a creature half reptile, half bird; +perhaps one-third reptile and two-thirds bird. It was about the size +of the crow. A little later unmistakable bird skeletons will appear, +but still their jaws are provided with long conical teeth.</p> + +<p>Still more interesting from our standpoint is another set of primitive +animals, utterly insignificant in<span class="pagenum"><a name="Page_183" id="Page_183">[Pg 183]</a></span> appearance, but of momentous +importance on account of their later history. Among these reptiles +were a few small creatures perhaps not much bigger than mice or moles. +Their teeth were a little more complicated and specialized than the +teeth of their reptilian cousins. Between their scales were small and +sparse hairs. Almost nothing but their jaws remain to-day to tell us +anything about them. But in this humble little creature of the +Mesozoic, utterly insignificant beside the tremendous reptiles of the +time, we discern the ancestor of the mammals. These were the +progenitors of the horses and cows, of the cats and dogs, of the +monkeys and apes, of the men of to-day.</p> + +<p>During this chalk period, which forms the last portion of the age of +reptiles, life for the first time grew to look much as it does to-day. +Now, apparently, the cold of winter and the heat of summer followed +each other in regular succession. There have been colder and warmer +periods at various times in the previous history of the earth, but +undoubtedly they were more uniformly cold or uniformly warm than now. +Ages were warm, or ages were cold, but now the earth clearly shows the +annual alternations of summer and winter, and for the first time +clearly shows the bands of climate on the earth which we know as +zones.</p> + +<p>In the chalk period this new factor of cold works<span class="pagenum"><a name="Page_184" id="Page_184">[Pg 184]</a></span> mightily in favor +of the mammals. Their reptilian ancestors were cold blooded. When the +climate was warm they were active; when the climate was cold they were +sluggish. With the continuation of the annual alternations of cold and +warm weather that had now set in upon the earth, the little birds and +mammals had in their warm blood an advantage which, in the long run, +enables them not simply to compete with their reptile forefathers, but +to outdistance them absolutely in the race. Here and there, on earth +to-day, exist a few big reptiles like the crocodiles and the boa +constrictors. But they are few and comparatively insignificant among +the multitudinous population of the globe and are confined to the +hotter portions of the earth. For the most part, the reptiles now play +an insignificant and unobtrusive part. The little molelike creatures, +practically unnoticed between their feet in the later Mesozoic, have +come to supplant them entirely, and almost to rival them in size. +While the reptiles have grown steadily smaller, the mammals have +steadily become larger.</p> + +<p>While there is no land mammal to-day as big as the heaviest of the +reptiles in the Mesozoic, the whale, which is one of the mammals that +has again taken to the ocean, surpasses in size even those gigantic +creatures. There never lived in the world before a creature quite so +big as the biggest of our whales.<span class="pagenum"><a name="Page_185" id="Page_185">[Pg 185]</a></span> Size, however, is not the most +important point in any animal. Speed, sagacity, variability, and power +of adaptation, these are the qualities which the world prizes, and +these the new mammals possessed.</p> + +<p>The next geological era is the Cenozoic, or period of modern life. +This is divided into two quite distinct sections, the Tertiary and the +Quaternary. This era began about five million years ago, roughly +speaking, and is still going on. The greater half of it is known as +the Tertiary. It was during this time that the mammals came to their +own. At first these creatures belonged to what the scientist knows as +generalized types. They are jacks-of-all-trades. The student of early +animal life finds in the little Phenacodus, which was scarcely bigger +than a good-sized setter dog, the beginnings from which many forms +have subsequently developed. This creature showed points of structure +which to-day may be seen in such diversified animals as the dog, the +horse, the rabbit, and the monkey. It is not, of course, suggested +that Phenacodus was the immediate ancestor of any of these. But there +were no animals in those times more like these I have mentioned than +was Phenacodus, and from forms like it in main features all of these +other animals have since been derived, each species of animal having +become adapted to one particular kind of life. The development of +diversified situations on the<span class="pagenum"><a name="Page_186" id="Page_186">[Pg 186]</a></span> earth, the varieties of climate, the +variation between marsh and upland, between valley and plateau, +furnish a complexity of environment into each niche of which a new +form of animal fitted itself.</p> + +<p>With the increased complexity of mammals comes the submergence of the +reptiles and amphibians to-day. In all sorts of situations we find +mammals. The old-fashioned continent of Australia is separated from +everything about it by deep water, impassable to any animal which +lives upon it. In this secluded country evolution is very slow and +animals are very antiquated. We still find there mammals with the +ancient habit of laying eggs in a hollow in the ground, though after +these eggs are hatched the young are nursed on the milk of the mother. +But on the great continental stretches, where competition is keen, +where the animal must battle for his life against a wide field of +other animals, where migration into new situations is possible, the +rapidity of the development has been very much greater.</p> + +<p>It is in such a situation that man has arisen. In the extreme +southeastern portion of Asia, and on the islands lying close to the +coast, his highest non-human relatives, members of the ape family, +have reached their best development. These, of course, are not man's +ancestors. They are the less progressive members who are left behind +entirely in the race.<span class="pagenum"><a name="Page_187" id="Page_187">[Pg 187]</a></span> Whether we have to-day any traces of the steps +by which man arose from the animal beneath him is vigorously disputed. +Eminent scientists will be found on both sides of this question.</p> + +<p>Many scientific writers to-day take it for granted that one form, +discovered in Java, while it may not be in the absolutely direct line, +must be very close indeed to the line of ascent toward man out of the +apelike forms. A scientist by the name of DuBois, working in the banks +of a stream in south-central Java, found a thigh bone which seemed to +him exceedingly human in its general character and yet not absolutely +like the human thigh bone. The oncoming of the rainy season raised the +water in the river so that DuBois could not continue his search. +Returning a year later, and digging back deeper into this bank, he +found a skull cap and two molar teeth which seemed to him to belong to +the thigh bone, although they lay several yards farther back, but at +the same level in the bank.</p> + +<p>When these bones were subsequently presented to a meeting of European +scientists by DuBois, he claimed to have found the "missing link" for +which there was so eager a demand. Some of the best anatomists of the +meeting, notably Virchow, laughed at his claim and said that the skull +cap was simply that of a human idiot, and could be duplicated in any +large asylum.<span class="pagenum"><a name="Page_188" id="Page_188">[Pg 188]</a></span> A committee of twelve naturalists was appointed to +report upon DuBois' find. Of this committee three asserted the bones +to be those of a low-grade man, three insisted that they belonged to a +high ape, of a type somewhat higher than any we know to-day, but still +distinctly an ape. Six members of the committee of twelve agreed that +the remains were those of a creature higher than an ape and lower than +any normal man, and represented, in their opinion, a stage distinctly +along the line of development out of the apes and into man.</p> + +<p>This so-called "Java find" is known in science by the name of +Pithecanthropus, which means the ape-man. Whether we look upon this +fossil as a serious find or not, it is very certain that in the caves +of Europe belonging to the Quaternary period we find abundant +evidences of primitive man. The older these evidences are, the more +likely they are to be distinctly below the grade of man of to-day, in +the size and shape of the brain case and in the length and massiveness +of the jaw.</p> + +<p>There are probably more races than one represented among these skulls. +Some of them are surely well-deserving of the title of low brow. Their +heavy ridges over the eyes, their small foreheads, their massive, +heavy-set jaws show a race of men far less endowed mentally and much +better endowed in the<span class="pagenum"><a name="Page_189" id="Page_189">[Pg 189]</a></span> matter of brute force than the men of to-day. +These skeletons, or parts of skeletons, are turning up every year, and +we are just beginning to know much about them. Capable men are +studying them with much care. The next fifty years may not improbably +make the history of the ascent of man as clear as is now that of the +horse, to which we shall refer later.</p> + +<p>The whole question of the descent of man from the lower animals, or +his ascent from them, as Drummond aptly termed it, is to most people +so entirely repugnant as to set them at once, and finally, against all +willingness to consider the question of Evolution. This, however, does +not solve the problem. Even though truth be horribly unpalatable, it +is still to be believed if it is only the truth. There is practically +no doubt left among scientific men of the origin of man in lower +forms. The evidences grow more and more complete year by year, and +from every line of investigation. Whether we study his anatomy, his +embryology, his history, his language, or his civilization, all +indications point in the same direction. Constant discoveries indicate +the fact of an enormously long development from a very humble form. If +this proves to be true and remains unpalatable, the fault lies in the +palate and not in the truth. Gradually we are coming to understand +that there is no reason why this truth should be unpalatable. We +consider a rise<span class="pagenum"><a name="Page_190" id="Page_190">[Pg 190]</a></span> from humble conditions to be the glory of our heroes; +we esteem it an added charm in their strength that they should have +developed from untoward surroundings. It is not a disgrace to man to +have descended from the apes. It is to the glory of man that he should +have ascended from forms not much more promising-looking than the apes +of to-day. We must repeat, however, that the apes were the +unprogressive members, and hence we must not judge man's ancestors too +harshly. It must have been in them to rise. But the great glory in the +thought of the humble ancestry lies in the possibilities of his +future. If out of a creature not materially unlike the gibbering ape +of to-day there should have come, under the guiding hand of an +Almighty God, creatures with the endowments and capabilities of man of +to-day, then this is only an earnest and foretaste of that which may +be expected in the future. A time will come when man shall have risen +to heights as far above anything he now is as to-day he stands above +the ape. Even then there seems no end. With Infinite Power as the +agent, and limitless time in which to work, man would be limiting God +to an extent unwarranted by the history of the past to imagine that +His process had stopped to-day, and that man, with his many +imperfections of body, of mind, and of morals, should be the best that +is yet to come. There cling to him still<span class="pagenum"><a name="Page_191" id="Page_191">[Pg 191]</a></span> the limitations and dregs of +his brute life. Often the brute in him comes to the surface. Little by +little he is coming to be dominated by the qualities God has last +given him. Slowly the brute shall sink away, slowly the divine in him +shall advance, until such heights are attained as we to-day can +scarcely imagine. As we can scarcely conceive the beginnings of this +process, so we can with difficulty imagine its end. This only can be +seen by the Eternal through whom it shall all come to pass, and by +whom all will in time be accomplished.</p> + + + +<div class="section_break"></div> +<p><span class="pagenum"><a name="Page_192" id="Page_192">[Pg 192]</a></span></p> +<h3>CHAPTER VII</h3> + +<p class="chapter_subhead">How the Mammals Developed</p> + + +<p>When the idea of evolution first began to be much discussed, +especially after the publication of the "Origin of Species," there +were several points which appeared to be more than commonly difficult +of explanation. It did not seem impossible that the various types of +domesticated cattle should have descended from a common ancestor. It +did not seem difficult of comprehension that the dog might once have +been a wolf. Though not quite so credible, it did not seem absurd that +the tigers, lions, and leopards should have once all been alike. The +resemblance between these are strong enough to make the idea seem +conceivable. Though men were willing to concede this much, they +insisted that the great branches of the animal kingdom varied so +widely from each other as to make it certain that each was a separate +creation. It was particularly objected that the mammals differed so +entirely from other animals in several important particulars that a +special divine act was necessary for their appearance. The mammals +have a furry cover<span class="pagenum"><a name="Page_193" id="Page_193">[Pg 193]</a></span>ing entirely different from the clothing of any +other animal in the kingdom, and have warm blood, which is found +nowhere else except among the birds. But particularly their method of +producing their young seemed so entirely different from that of any +other group that here a special creation was deemed absolutely +necessary.</p> + +<p>Other young creatures are produced from eggs laid by the parent and +subsequently hatched. The young of the mammals are born alive and +comparatively well developed. In addition, their first food, the milk +of the mother, is so entirely different from the food of any other +creature that this again seemed to involve a separate creation. +Gradually we have come to understand the whole matter of reproduction +very much better. Minute and careful dissections of rabbits, of dogs +and cats, of animals slaughtered for food, with occasional post-mortem +examinations of human beings in various stages of the development of +the young, leave us no longer in doubt concerning the main features of +the process. The better we come to understand it the more clearly it +becomes evident that in the development of the mammals we have no new +procedure, but, as in so many other activities, new developments of an +old process.</p> + +<p>There are two entirely different methods by which new animals and +plants may arise. One sees some<span class="pagenum"><a name="Page_194" id="Page_194">[Pg 194]</a></span>times in the home of a friend a +geranium of particular beauty, the like of which he would be glad to +possess. The accommodating friend cuts a small piece from the +geranium. This is stuck into poor but well-watered ground, develops +roots, and eventually grows into a geranium stalk exactly like the one +from which it came and of which it is in reality only a detached part.</p> + +<p>In similar fashion, if one wants a particular kind of apple, he never +trusts to planting an apple seed. Going to the tree of the variety he +desires, he takes from it a small twig provided with a bud and inserts +this bud into a cleft made in the young branch of another apple tree. +The young bud so inserted starts up into a new branch, resembling +almost absolutely, not the tree which feeds it with sap, but the tree +from which the bud was originally taken.</p> + +<p>When we wish a particular variety of potato we obtain pieces of the +potato of the kind we desire. Each of these must contain an eye, which +is a bud of the old potato. When the sprout appears the new plant will +be practically identical in character with the plant from which the +potato was taken. This sort of reproduction, in which a piece of the +old parent grows up into the new generation, is called the asexual +method. But one parent is concerned in the process,<span class="pagenum"><a name="Page_195" id="Page_195">[Pg 195]</a></span> and the offspring +are as nearly as may be like the parent from which they arose.</p> + +<p>The gardener who wishes to obtain new varieties is not content with +this method. If he plant the seed of the potato the outcome will be +most uncertain. His seed must be taken, of course, from the fruit of +the potato, and most of these plants never fruit. Every grower of +large quantities of potatoes will have noticed occasionally, on the +tops of the plant, after the flowers disappear, a globular growth +looking not unlike a small tomato, but with a tendency to become +purplish green in color. This is the fruit of the potato and in it are +the seeds. When these are planted all sorts of potatoes are liable to +start up. Most of them will prove worthless. An occasional seed may +produce an uncommonly fine plant. This new variety may thereafter be +propagated from the tuber, as the potato itself is called, and the new +strain will be kept constant in this way. This method of using the +seed for reproducing the plant is called the sexual method, because +two parents coöperate in the production of the seed. The pollen came +from one parent and the ovule, which after fertilization swelled up +into the seed, came from another. By this combination of two +individuals new varieties become quite possible. Nature seems to be +more concerned in improving her strain than in maintaining her older +strains. In all<span class="pagenum"><a name="Page_196" id="Page_196">[Pg 196]</a></span> of her lowest plants and animals she uses the asexual +method of reproduction. As we go higher in the organic world the +two-parent method becomes increasingly common. When we reach the +higher animals, and most of the higher plants, this plan of double +parenthood, the sexual method, alone is used.</p> + +<p>In order that we may the more clearly understand how the mammals +produce their young and nourish them, we shall begin at the lowest +class of the backboned animals and note how the process is there +accomplished. As we pass upward through the kingdom the method +acquires greater complexity. When we finally reach the mammals, what +at first seemed an absolutely new process will prove to be, as is all +of nature's work with which we are thoroughly acquainted, but a +modification and an elaboration of some previously existing process.</p> + +<p>Some time ago I was passing the early months of summer by the side of +a lake in northern Pennsylvania. Near my tent, on the edge of the +water, was a wharf from which it was possible to look down into the +shallows about the edge of the lake. In early July the bottom began to +take on a strange appearance. Spots as big as a dinner plate became +evident because they were cleaned of the finer sand or mud which is +common on the bottom. A close examination showed that each of these +circular spots was<span class="pagenum"><a name="Page_197" id="Page_197">[Pg 197]</a></span> being occupied and cleaned up by a sunfish. The +pebbles were lifted into the mouth of the fish and driven out again +with force. The water which emerged with the stones seemed to wash +away the dirt, while the pebbles themselves became gradually cleaned +of the green plant life which ordinarily covers them. After the +process was completed each spot was saucer-shaped and free from scum +and mud. Over each of these spots hovered the sunfish which made it, +and round and round the fish swam. The circles thus traversed were so +near each other that every now and then the occupants of two adjoining +nests would meet on the border. The fish which was most nearly on its +own ground would at once attack the other and drive him away. In a few +days the other partner in each family seemed to appear. Now two fishes +swam side by side over each nest, bringing the lower edge of their +bodies comparatively close together. In this position they moved +around over the pebbly bottom. The female was discharging her +multitudinous and very small eggs, so that they dropped to the bottom +of the nest. At the same time the male was expelling what in fish is +known as the milt. In this milt are the sperm cells of the male, each +consisting of a rounded head and a very slender body. These are +attracted by the eggs. Pushing up against them, the head of a sperm +cell, consisting almost entirely<span class="pagenum"><a name="Page_198" id="Page_198">[Pg 198]</a></span> of the nucleus of the cell and +carrying the determinants which were to decide one-half of its future +characters, penetrated this egg and fused with its nucleus. This was +filled with the determinants of the characters inherited from the +mother. Of course many of the eggs, of which probably there are a +thousand, must have escaped fertilization. There are doubtless a +thousand sperm cells that went to utter waste for one which found an +egg to fertilize. These eggs nestled in the crevices between the +stones in the warm water of the edge of the lake. Here the sun could +easily penetrate to the bottom and hatch them. The little fish, still +guarded by one hovering parent, swam around in the water long before +the yolk of the egg, containing its large amount of food, had been +absorbed into the tissues of the young fish. This fatty store made the +abdomen of the fish in which it lay protrude enormously. Gradually the +fish grew larger and the yolk grew smaller until all had been +consumed. Soon the fish began to forage for himself and no longer to +demand or care for the company and protection of its parent. The +little sunfish is highly favored among his comrades in having any care +whatever by the parent. In the case of most fishes the female, +swimming slowly over the bottom, deposits her eggs, which are +fertilized by the male, which follows behind her. After the eggs have +thus been<span class="pagenum"><a name="Page_199" id="Page_199">[Pg 199]</a></span> laid and quickened no other attention is paid to them by +either of the parents.</p> + +<p>Fish are stupid almost beyond the comprehension of those who are not +students of the minds of animals. Frogs and toads are a distinct step +in advance, and hence their mental activities play a larger part in +the process.</p> + +<p>In the love-making of the frogs and toads the song has an important +share. In each species the voice is a little different from that of +any other. In our familiar garden toad we have an excellent +illustration of the method common to the entire group. When spring +comes an impulse seems to stir in all the toads of a neighborhood. +Heretofore they have stuck faithfully to dry ground; now they start +off for the water. Whether their impulse is simply to move down hill +or whether they by some means detect the near presence of water, I +cannot say. Certainly a new fountain on a lawn will secure in spring +its prompt and full share of the neighborhood's toads. In any event +the toads of a district congregate in great numbers in any pond or +along the edge of any moderate stream. Within a short time their +flutelike, quivering voice is heard far and wide. That this note has +an attractive power over the female there is no doubt. She herself +makes no effort to imitate, but the song of her mate is persistent and +exceedingly<span class="pagenum"><a name="Page_200" id="Page_200">[Pg 200]</a></span> sweet. I have seen a male sit upon a clump of grass and +utter his love call. Before he had been singing for more than half a +minute three females hastened toward him from a distance of perhaps +twenty feet. Each seemed anxious to reach as promptly as possible the +creature whose voice had proved so attractive. When the mating comes, +the female discharges a series of small shotlike eggs which are +encased in a very tenacious mucous. While they are being deposited the +male fertilizes them. No sooner have the eggs, fertilized by the sperm +cells, reached the water than the mucous at once begins to swell. The +result is that eggs appear encased in two slender strings of jelly, +each having a diameter about that of a lead pencil. At intervals of +not more than half an inch the shotlike eggs may be seen. The mother +toad, in laying these eggs, moves about rather restlessly in the +water. By this means she succeeds in wrapping the strings about the +grass and sticks of the pool. This will hold them quite safely even +against a considerable current of water, should the stream rise and +flood the side pools in which the eggs are laid. With this amount of +care, however, the attention of both parents to the young entirely +ceases. They are now abandoned to the chances of a fortune to them +exceedingly unkind. A toad will lay about five hundred eggs. It is +evident that on the average only two of<span class="pagenum"><a name="Page_201" id="Page_201">[Pg 201]</a></span> these can attain maturity by +the time the parents have died, for the number of toads does not +materially alter season by season. The connecting string is made up +not of nourishment for the eggs, but of a bitter mucous so unpleasant +to the taste that fish are thus deterred from eating the otherwise +nourishing material. This secures for the young embryo a chance to +mature which in the absence of the jelly it would entirely lack. +Imbedded in this mucous is the embryo itself, surrounded by a small +amount of albumen and containing inside of itself a very considerable +amount of yolk. This gives to the egg a volume possibly a hundred +times that of the egg of the sunfish. Thus, even counting the care the +parent sunfish took of its offspring, which care is very uncommon +among fishes, the toad stands a distinctly better chance in life. The +protection of the bitter mucous and the large amount of yolk +permitting considerably larger development before leaving the egg, +give to the toad a material advantage. When the toad first emerges +from the egg it is amazingly like the fish. It has gills at the side +of its neck and swims by the movement of its tail. Later its limbs +develop, the hind ones coming first, its tail is absorbed, and it is +now a true toad, ready to leave the water.</p> + +<p>Altogether a higher state of reproduction is encountered when we reach +the reptiles, which are the<span class="pagenum"><a name="Page_202" id="Page_202">[Pg 202]</a></span> next higher class of backboned animals. +Here very distinct developments of the process are discovered. The +turtle, to use the best known illustration, may lay but twenty eggs. +But she will not lay them at random in the water, as do the toads and +the fish. Each egg is wonderfully fattened with yolk. This means that +it is possible for the creature to develop to a far greater extent +before leaving the egg than was possible in the case of the toad. +Accordingly the little turtle, while it begins life not unlike a fish +and goes through the gilled and tailed period, during which it is not +unlike a tadpole, passes beyond this period before leaving the shell +and has already acquired its full turtle characters when first it +steps upon the scene. So big an egg as this would be highly nutritious +and animals would desire it immensely for food. Hence it becomes +necessary for the turtle to securely hide her eggs. In order to do +this, she scoops out a pit in the sand in which she deposits them and +here they develop. If no further provisions were made the eggs of the +turtle would dry completely and never hatch. Accordingly it becomes +necessary for the turtle to enclose each egg in a tough, leathery +membrane, known as the shell. Because the egg is thus encased it is +necessary for it to be fertilized before being laid. Accordingly the +male must place the sperm cells within the body of the female.<span class="pagenum"><a name="Page_203" id="Page_203">[Pg 203]</a></span> These +cells swim nearly to the top of the tubes in which they are placed, +and there fertilize the descending eggs. Farther down the canal the +shell is secreted about the now swollen mass of yolk and white, +completing the egg just before it leaves the parent.</p> + +<p>If the evolutionist understands properly the line of descent, the +birds and mammals are both the descendants of the reptiles. While +there is less exterior resemblance between a chicken and a turtle than +between a cat and a turtle, the real relationship in the first case is +much closer than in the second. This is perhaps most easily seen in +the scaly legs of both bird and reptile. Another remarkable +resemblance lies in the fact that in both cases the eggs are large, +well stored with nourishment, and protected by a resistant shell.</p> + +<p>So few people know the turtle's egg that it will be better to describe +that of the hen, which it largely resembles. Underneath the hard shell +is a tough but flexible membrane which lies against the limey coating, +except at the blunt end, where a separation between the two gives room +for a bubble of air. Inside of this shell and its membrane lies the +white of the egg, which is nourishment for the chick, though not +nearly so rich as the yolk. This, besides the albumen which it +contains, is stored with large quan<span class="pagenum"><a name="Page_204" id="Page_204">[Pg 204]</a></span>tities of fat. It will be +remembered that upon breaking a hen's egg and dropping it into a bowl, +the yolk holds together because it is enclosed in a delicate sac. As +the yolk falls into the bowl there floats to the top of it a lighter +yellow spot as big as the end of a lead pencil. This is all of the egg +which thus far represents the chick itself. All the rest is +nourishment. This disk already consists of three reasonably +distinguishable layers of cells, which grow rapidly different from +each other. They spread and bend and twist, forming the young chick +and a set of organs which serve for its protection and maintenance +during its embryonic life. Within a few days these accessory organs +will have formed distinctly. Within the upper half of the yolk will be +found the small developing chick, which for the first thirty-six hours +of its development passes through a stage not unlike the fish, or the +earlier steps of the turtle. Within a few days it becomes clearly +evident that this creature is to be a bird, though it is much longer +before it is clearly a chick.</p> + +<p>This embryo is so soft that it is almost like curd in thickened milk, +and could be very easily destroyed were it not for a protective device +which Nature has employed. It seems necessary that it should be +protected with the utmost care. The matter will be better understood +if we recall a common experience.<span class="pagenum"><a name="Page_205" id="Page_205">[Pg 205]</a></span> Almost everyone has tried to +dissolve some substance in water in a vial. If the bottle be filled +with fluid to the top and corked it is very difficult to shake up the +contents. Even vigorous agitation produces little movement of the +material on the inside. If we wish to shake up the solid with water +the bottle must be left partly empty. The brain of a human being is +protected by just the same device. If it simply lay within the skull +the first fall would mash the gray substance against the side of the +cavity. To prevent this calamity the bony case is made somewhat larger +in capacity than the brain itself, and the space between the two is +filled with a watery fluid. This serves to prevent jars and shocks. In +the hen's egg the same plan is pursued. The embryo lies on the inside +of a bag considerably larger than itself. This sac, called the amnion, +is filled with a watery fluid. With such a protection only the most +severe shock to the egg would sufficiently jar the embryo to do it any +harm. The ordinary experiences of an egg leave it undisturbed.</p> + +<p>Every living creature requires a constant supply of food and of +oxygen. The embryo is a living creature, and is no exception to the +rule. It needs an abundant supply of easily assimilated food and of +oxygen. When the hen's egg is first laid the entire contents, with the +exception of the little light-<span class="pagenum"><a name="Page_206" id="Page_206">[Pg 206]</a></span>colored disk which floats on the top of +the yolk, form the nourishment. The disk alone is the living organism. +In the earliest stages the embryo receives its food by simple +absorption from the yolk. As the chick increases in complexity the +yolk at first grows swampy, with fluid trickling here and there +through the more solid portions. Thin walls form about these little +streams, thus producing blood vessels which cover the entire surface +of the yolk. These absorb the nourishment and turn it over to the +embryo. As the latter grows in size both the yolk and white diminish. +The embryo soon becomes larger than the remaining yolk and is attached +to it by a cord filled with blood vessels which enter the chick near +the center of its body. The abdominal wall has an opening at this +point. One of the later occurrences in the life of the chick, before +it breaks through the egg, is to have the last remnant of the yolk and +its sac slip to the inside of the abdomen, which then completely +closes over it.</p> + +<p>As yet, we have seen no arrangement for furnishing air to the chick. +At the same point at which the blood vessels from the yolk enter the +chick, another set of vessels pass in and out. These are attached to a +large flattened bag which floats above the embryo against the upper +side of the shell. This bag is called the allantois, and serves as a +sort of lung for<span class="pagenum"><a name="Page_207" id="Page_207">[Pg 207]</a></span> the developing chick. The shell is porous enough to +allow air to pass through it. The blood vessels of the allantois take +in oxygen and give out carbon dioxide through the porous shell. The +blood thus altered is returned to the chick and serves its life +purposes. One of the reasons why the chicken must turn its eggs in the +nest is that, if the allantois remain too long in contact with the +upper shell of the egg, it will become attached to it and will not +thereafter perform its functions.</p> + +<p>The embryo thus enclosed in the egg finds its protection in the fact +that it is encased in a fluid contained in the amnion. It draws its +nourishment from the yolk upon which it lives and the nourishment is +transmitted to it by blood vessels. It draws its oxygen and throws off +its wastes through the instrumentality of the allantois, which covers +it over. Day by day the chick becomes larger, day by day it grows to +look more like what it is to be. By the nineteenth day it appears to +be complete. Its nervous organization is, however, not thoroughly +developed. If removed from the shell the chick still is indisposed to +stand upon its feet or to run about. If allowed to remain in the egg +until the twenty-first day, the chick will be able to push its beak +through the skin enclosing the bubble of air at the blunt end of the +egg and get the first breath into its lungs. Now it gives a<span class="pagenum"><a name="Page_208" id="Page_208">[Pg 208]</a></span> faint +peep, breaks the shell of the egg, and steps out into the open air.</p> + +<p>I have given this somewhat lengthened description of the development +of the chick because of the light it throws upon the method pursued by +the mammals. The features which have been described in the case of the +chicken's egg could be as fully observed in the case of the turtle or +any of the other reptiles. Mammals are descended from the reptiles of +the Mesozoic, and whatever peculiarities there may be in their method +of producing their young must be derived from the reptiles. If we wish +to know how the earliest mammals produced their young, we can only +judge by the lowliest members of the group that live upon the earth +to-day. The most primitive of these is the so-called Duckmole, of +Australia. This little creature has habits not unlike those of the +muskrat. It burrows in the bank of a stream, and makes a nest at the +end of the burrow, where it lays its eggs. This is one of the very few +warm-blooded, hair-covered animals which still lays eggs. A little +higher in the scale stand the kangaroo and the opossum. These +creatures keep the egg inside of the body until it is hatched. But +this happens in so short a time that the young animal is exceedingly +immature and as yet unable to stand the outside air. Accordingly there +is a double fold of skin on the abdomen of the<span class="pagenum"><a name="Page_209" id="Page_209">[Pg 209]</a></span> mother, covering her +breasts. This forms a suitable resting place into which these young +are conveyed as soon as they are born and from which they do not +emerge for many days. The little creature instantly fastens upon the +nipple of the mother, keeping its mouth constantly in this position. +At intervals the muscles of the breast force the milk into the mouth +of the young, which is still too undeveloped to suck for itself. As it +gets older the little opossum or kangaroo emerges from the pouch in +the pleasanter part of the day and in the absence of danger. It +returns to the mother's pocket as soon as it becomes cold or a cry +from its parent warns it of its defenseless position.</p> + +<p>These creatures are the lowliest of the class upon the earth. The +great majority of all mammals have elaborated a far finer plan, in +which the young are retained within the body of the parent until they +are quite able to stand the air. The length of this time varies in +different mammals from a few weeks to more than a year. The egg must +be fertilized before it leaves the body of the parent. If it should +fail in this it simply passes out and is wasted. If the fertilizing +cell reaches the egg before it has progressed far down the tube it +begins its development. The embryo forms for itself the sort of head +and tail and gill slits which would have served its fish or its<span class="pagenum"><a name="Page_210" id="Page_210">[Pg 210]</a></span> +tadpole ancestor. Its limbs develop as little buds indistinguishable +from similar buds that would have formed fins for the fish or wings +for the bird.</p> + +<p>Around the embryo there forms a sac, the amnion filled with a fluid +which serves to protect the young mammals exactly as the growing chick +was protected. Under the forming creature there hangs a small but +empty yolksac. This is an actual remnant, a reminder of the past, when +the eggs of the mammals were also packed with yolk and the growing +embryo secured its nourishment exactly as does the maturing chick. But +a new method has been provided for the mammal, and consequently the +yolksac, though it has not entirely disappeared, has no nutritive +content for the growth of the embryo.</p> + +<p>The allantois of the chick now gains a new development and an altered +function. In the case of the chick it floats against the shell of the +egg and absorbs oxygen through the shell. Inside the body of the +mammal this is impossible, because the air is too far away. No shell +is formed about the egg because it is not to be laid. The tube of the +parent's body in which the egg lies becomes thickened at the point of +contact with the egg. It grows spongy and full of blood vessels. +Meanwhile the allantois is also growing spongy. These two tissues are +so closely pressed against each other that the blood vessels of the +trans<span class="pagenum"><a name="Page_211" id="Page_211">[Pg 211]</a></span>formed allantois mesh in with those of the thickened parent +wall. Thus the blood vessels of the mother are brought into close +contact with those of her offspring. Her blood seeps over into the +transformed allantois which is now called a placenta. From this it is +handed over to the offspring, which thus receives from the mother her +blood, and returns its own used blood for enrichment and purification. +So the allantois of the reptile has become the placenta of the mammal. +In the first instance it served only as an organ of respiration. Now +it has come to supply the embryo with rich blood containing both food +and oxygen derived from the mother. After the offspring is born this +thickened pad breaks loose, and subsequently is also extruded from the +body, forming what is known as the afterbirth.</p> + +<p>Thus far we have spoken of the change in the method by which the young +are brought to such a stage of development that they can stand the +outer air. One of the improved differences between the mammals and +other animals lies in the method by which they nourish their young for +some time after birth. The very word mammals signifies an animal who +is in the true sense of the word a mamma. This name for mother is +given to her because of the fact that she possesses what are +technically known as mammary glands, or, in simpler language, breasts. +It<span class="pagenum"><a name="Page_212" id="Page_212">[Pg 212]</a></span> would seem as if here we had an entirely new organ. No other +animal gives nourishment to its young in such fashion; all mammals do. +What is the origin of the habit? How did the organ arise?</p> + +<p>A part of an animal's body that has the power to gather material from +the blood and pour it out in the shape of fluid is known as a gland. +Sometimes a whole organ does nothing else. Sometimes small glands are +scattered through, or over, the surface of another organ. There are +two kinds of glands in the skin of the mammal. The best known and most +frequently thought of are those which pour out the perspiration. These +have a double function. In the first place they assist in keeping the +temperature of the body uniform. When we are too warm they pour out a +watery fluid over the surface of the body. If the air is dry enough +and our body not too closely protected by clothing, this perspiration +passes off in the form of vapor. All evaporation requires heat, which +in this case is extracted from the body. So soon as the temperature +returns to its normal level the flow of perspiration ceases. The other +function of the sweat glands is to take from the blood some of the +waste matters of the body and pour them out upon the surface. This is +done in order that the body may free itself from substances which, if +they were to accumulate, would have a poisonous effect upon<span class="pagenum"><a name="Page_213" id="Page_213">[Pg 213]</a></span> its +action. It is this function of the sweat glands which makes it +necessary for us to bathe the surface of our bodies with water. Dirt, +in the ordinary sense of the word, is not harmful to a sound skin. Our +reason for bathing is really to remove the wastes which we ourselves +have poured upon the surface of the skin. These, if allowed to remain, +soon decompose, like all nitrogenous substances, and become very +offensive. They may then be reabsorbed into the skin and nature's +effort to throw them off has been in vain. These glands, since they +contain waste matter, could not possibly yield food for the young. +They would poison and not nourish. Hence, whatever the breasts may be, +they are not altered sweat glands.</p> + +<p>There is another set of organs in the mammalian skin. At the base of +each hair lies an oil gland. The function of these is to pour out a +substance which spreads along each hair and over the surface of the +body. The outside of the skin is always dead, and would easily crack +were it not for the constant secretion of this oil. In winter, when +the blood circulates less freely and these glands consequently pour +out less oil, the supply frequently runs short. If what little is +poured out is too frequently removed by washing, the skin becomes +brittle, and, on bending a joint, the epidermis cracks. The gloss of +the hair is due to the oil thus poured out. This oil becomes one +ingre<span class="pagenum"><a name="Page_214" id="Page_214">[Pg 214]</a></span>dient in the milk produced by the transformed gland. But there +is another important constituent. When one does unaccustomed manual +work the ordinary result is the formation of a blister. The epidermis, +or scarfskin, becomes detached from the dermis, or true skin, and the +space between the two rapidly fills with the fluid portion of the +blood, known as lymph. The fact that no blood vessels have been broken +in this detachment results in there being no red corpuscles in this +fluid. Wherever a cavity forms in the body lymph is liable to enter +it.</p> + +<p>The milk glands of the mammals are modified oil glands. The fluid +which they now pour out is no longer exactly the old oil with the +addition of the lymph. Undoubtedly in the past the first milk was more +like this simple mixture. There seems no doubt that the breasts of +to-day are the enlarged and modified oil glands of earlier mammals. In +one of the most primitive of our mammals the young simply lick certain +bare spots on the surface of the mother's abdomen. As higher forms +arise there develops a smaller or larger mound with a distinct +projection, about which the lips of the offspring can easily fasten. +Lamarck would have said that the suction of the infant had produced +such a mound, and that this had been transmitted to later offspring +until it had grown to be the highly developed organ we now find, for +in<span class="pagenum"><a name="Page_215" id="Page_215">[Pg 215]</a></span>stance, in the cow. Since, however, we have come to disbelieve in +the transmission of acquired characters, this explanation will no +longer serve. We must content ourselves with saying that, by whatever +accident the nipple arose, the success of it when present determined +its selection by nature and its consequent persistence. With increase +in its function has come increase in the size of the glands. Lower +animals which, like the hog, produce a large number of offspring, +possess a large number also of these glands. With the diminishing +number of young and greater care of them as we rise in the scale has +come also a diminishing number of breasts in the female. Whether those +on the front of the body should persist, or those on the rear, depends +upon other factors in the life of the animal. Hoofed animals, perhaps +because their best weapon is the hoof and they can there best protect +their young, have retained them in the rear of the body. In the group +of animals known as the primates, including monkeys, apes, and man, +the habit of holding the young in the arms for protection has +determined the persistence of the breasts upon the chest rather than +the abdomen.</p> + +<p>It is interesting to notice that the habit of the elephant of +protecting its young by means of its tusks has also resulted in a +similar position of the milk glands.</p> + +<p><span class="pagenum"><a name="Page_216" id="Page_216">[Pg 216]</a></span>That the primates had once a larger number of offspring is confirmed +by double evidence. Even to-day the number of children at a birth is +often two, sometimes three, rarely four. The day before this was +written came the report of a case of five children at a birth, all of +whom seemed sound and all of whom lived. Still more direct evidence is +found in the fact that occasionally in the human female there are two +pairs of breasts, and very rarely three pairs. These are then disposed +in a double line down the front of the body.</p> + +<p>The new plan of caring for the young is one of the priceless heritages +of the higher animals. As we rise in the grade of life the number of +the young produced at one time steadily diminishes, while the care +spent upon them increases. The shad may lay four hundred thousand eggs +and trust them entirely to their fate. The sunfish will lay a +thousand, by no means all of which can be fertilized, but it guards +them somewhat after deposition. The toad lays several hundred, stores +them with a considerable amount of nourishment, and protects them by a +bitter deposit of mucous. The turtle has reduced the number of eggs to +perhaps a score. Each of these is supplied with abundant nourishment, +so that the young may develop to considerable size and activity before +emerging from the egg. This material is enclosed in<span class="pagenum"><a name="Page_217" id="Page_217">[Pg 217]</a></span> a firm protective +shell and hidden away from sight by being buried in the ground. In the +mammals comparatively few eggs are produced at one time. These are +fertilized within the body of the parent, are attached to the parent, +and absorb her blood. No shell is needed because nothing will kill the +developing offspring that is not likely to injure the parent. Not only +do the young feed upon the blood of the mother up to the time of +birth, but they are practically dependent upon this same blood after +birth. Though they do not take it directly from the veins, the milk +is, none the less, the transformed blood of the mother. This assures +the young of food as well as of protection. Best of all, the young are +provided with the companionship of the mother. Now for the first time +animals learn by example. Heretofore they have been born with a nearly +undeviating instinct; now intelligence begins to arise. They can +imitate their mother. Heretofore no acquired characters affected the +young. In the mammals, although the young cannot inherit the acquired +habits of the parents, they can get them by imitation, which serves +nearly as well.</p> + +<p>There is, however, a more wonderful advantage that comes from the +close attachment between mother and offspring. This intimate +relationship brings about an affection of the mother for her young +heretofore unknown in the animal world. It is somewhat<span class="pagenum"><a name="Page_218" id="Page_218">[Pg 218]</a></span> paralleled +among birds, but here the care of the nestling is less intimate, far +less maternal, than the care of the mammal for her young. As the +number of the young grows less and the care taken of them increases, +the intensity of the affection also increases. By the time we get as +high as the dog or the cat this fondness becomes a fierce, +self-sacrificing love. When we come to man, with his high intellectual +powers, with his deeper moral sense, we find a wonderful change. This +love of the mother for her child has grown into the finest emotion +possible to the human heart. It no longer is confined to the dependent +life of the child, but follows the offspring through its entire life, +guiding, guarding, shaping its destiny, handing on to the child the +treasured wisdom of the race. Influenced by the example of the mother, +the father comes to have a love for his children. It is not so strong +as that of the mother, nor so utterly unselfish, but it is still a +noble and exquisite love. Developing in a different direction, the +love of the mother for her children grows as civilization advances, +and spreads over the father of those children as well. Again +reflecting her love, the man finds himself filled with a new feeling +for the woman. It is never as unselfish, as free from desire, as is +her love, but it completely transforms his relation to her. What has +been with him simply desire is ennobled and enriched<span class="pagenum"><a name="Page_219" id="Page_219">[Pg 219]</a></span> until it becomes +the finest passion of his life, absolutely transforming him, in +relation to her, from a selfish brute into a tender and life-long +companion. So utterly does the love thus engendered transfigure human +life that when we seek to express the divine nature in human terms, +and these are the only terms we know how to use, the richest +revelation that has come to us is the conception taught by the Master +that "God is Love" and that "as a father pitieth his children, so the +Lord loveth them that fear him."</p> + + + +<div class="section_break"></div> +<p><span class="pagenum"><a name="Page_220" id="Page_220">[Pg 220]</a></span></p> +<h3>CHAPTER VIII</h3> + +<p class="chapter_subhead">The Story of the Horse</p> + + +<p>Ever since men have been familiar with the idea of evolution there has +been a temptation on the part of the zoölogist to draw up pedigrees +expressing the relationship between the various groups of the animal +kingdom. The impulse is natural, and, if the resulting tables are not +accepted with too much confidence, the result is not undesirable. The +truth of the matter is that all of these pedigrees are more or less +hypothetical. They simply show what connection seems most likely. In +all of them are spaces filled with doubtful names. Each addition to +our acquaintance with the past history of animals necessitates +revision of our tables. The student of fossils, trying to rebuild in +imagination the world of the past, finds himself often strangely +unable to link these animals together. The result is that the more we +know of fossils, the more distrustful we become of the easy +connections we have been making between groups. Accordingly we are +more than commonly pleased when we find the clear indication of a +genuine pedi<span class="pagenum"><a name="Page_221" id="Page_221">[Pg 221]</a></span>gree, actually illustrated by real examples, following +each other in time through the geological history. A few of these +lines are gradually becoming plain, and none of them is clearer than +the pedigree of our familiar and much loved horse. The example is a +particularly interesting one, not only because of our affection for +the animal, but because the horse originated in all likelihood in +North America on the land occupied to-day by our Western plains. As +though he loved the country of his ancestors, he returned after having +circled the globe, and once more went wild in the home of his +forefathers. The problem was first worked out in Europe and later +elaborated in this country. Now the history gets its finest expression +in the American Museum of Natural History in New York City. The +collection of fossil horses in that institution surpasses in +completeness and in excellence of mounting and of sympathetic +restoration any similar collection representing the ancestry of any +other animal in the world.</p> + +<p>In the <a href="#geological_times">table of Geological Times</a>, given in chapter six, the era of +recent life known as the Cenozoic is seen to occupy something like +five million years. This figure, as was previously suggested, is very +uncertain, and may be three or may be six, but is safely represented +in millions. Through most of this time stretches what is known as the +Age of Mammals, the<span class="pagenum"><a name="Page_222" id="Page_222">[Pg 222]</a></span> Tertiary Age. Its close, occupying only the last +few hundred thousand years, is known as the Age of Man, the +Quaternary. Through perhaps three or four millions of these years +stretches the known pedigree of the horse.</p> + +<p>When we go back to the early Tertiary we find a forest, with trees +that shed their leaves, interspersed with glades, in which already the +grasses were beginning to be developed. This state of affairs had +existed but for a comparatively short time, geologically speaking. It +had come only in the latter part of the preceding era. Lake and swamp, +meadow and forest intermingled to make a rich and varied scene. Slowly +the land toward the western side of North America lifted itself into +plateau and mountain range. Slowly the westerly winds began to be cut +off by the barriers thus raised across their path. As they swept over +the plateau and down into the eastern plain their moisture came to be +diminished. Gradually a very different state of affairs set in. The +ground became harder, the forest became sparser, the plants became +higher and firmer, the grasses tougher and more wiry, and, by the time +the Quaternary arrived, a condition probably even drier than that of +to-day existed over our western highlands. Throughout this long +change, spread over millions of years, a creature which has become our +horse steadily persisted<span class="pagenum"><a name="Page_223" id="Page_223">[Pg 223]</a></span> and steadily advanced. Side lines developed +which finally disappeared, but the main line kept on, and when the +Quaternary came the horse arrived with it. Many of the skeletons in +this series were known before it was realized what they were. As time +went on and intermediate forms were found, it became possible to +recognize these as ancestors of the horse and to assign them their +proper position in the family tree.</p> + +<div class="figcenter" style="width: 500px;"> +<img src="images/horsefoot.png" width="500" height="352" alt="THE EVOLUTION OF THE HORSE'S FOOT" title="THE EVOLUTION OF THE HORSE'S FOOT" /> +<span class="caption">THE EVOLUTION OF THE HORSE'S FOOT<br /><br /> +<em>After H. F. Osborne and Charles R. Knight. By permission of the +American Museum of Natural History.</em></span> +</div> + +<p>The earliest of the forerunners of the horse with which we are +acquainted would certainly not be recognized as such by any but the +most careful student of<span class="pagenum"><a name="Page_224" id="Page_224">[Pg 224]</a></span> animals, if we could see him to-day. He stood +not higher than a fox-terrier dog, though his shape was very +different. But he would probably be more likely to be classed with the +dog than with the horse by the hasty observer, for he walked with four +toes of each foot upon the ground as the dog does to-day. Like the +dog, he had hanging at the inner side of his front foot a little +useless toe. He was long in body, comparatively short of leg, a little +long of head and neck, and distinctly long of tail. His grinding teeth +had points on them not unlike a pig's, and possessed no apparent +resemblance to the wonderful curved and ridged surfaces seen on the +teeth of the modern horse. What his skin and hair were like can only +be conjectured. In the restoration which Mr. Knight has made, at the +suggestion of Professor Osborne, an interesting inference has been +drawn. That he was a creature of the forest is suggested by his +spreading toes, which would keep him from sinking in the soft soil. It +is consequently surmised that he was dappled with spots which allowed +him to rest unnoticed on the sun-flecked floor of the forest. Mane he +had none, and his tail was probably tufted slightly at the end with +hairs, which were increasingly short as they approached the top. He +had no forelock, and the hair along the ridge of his neck was a little +longer than the rest, and stood erect. Browsing about on<span class="pagenum"><a name="Page_225" id="Page_225">[Pg 225]</a></span> the soft and +tender herbage of his woodland home, his teeth had as yet no tendency +to become specialized. The molars had mounds upon them, developing, +perhaps, more into the shape of the points of the hog's, but even +still quite generalized teeth. His main enemies, from whom, perhaps, +he could with little difficulty escape, were creatures related to the +hyenas of to-day. Perhaps, like their modern representatives, they +preferred eating their flesh tainted to exerting themselves enough to +capture and kill their prey. By the time we advance a little further +into the Tertiary, though still in its early portion, a remarkable +change has already come about. The fifth toe, which in the earliest +horse hung upon the side of the front foot, has completely +disappeared. The change in the hind foot has gone still further. The +hind leg in many animals evolves more rapidly than the front. The +heavy work of running is always done by the hind feet, while the front +feet serve rather as a prop to keep the animal from falling than as +the actual means of locomotion. Hence the hind feet and the muscles of +the hind quarters are almost always heavier than the front. Possibly +on the front foot the little fifth toe was less of an obstruction, and +persisted after the early horse had lost the corresponding toe on his +hind foot. This process has gone on still further in this second +stage, and the hind foot<span class="pagenum"><a name="Page_226" id="Page_226">[Pg 226]</a></span> has but three toes, while the front still +has four. This is not the only advance. Already the middle toe of the +original set of five is becoming emphasized. The weight is thrown more +forcibly upon it, as with the human foot it is upon the inner or big +toe. The middle toe is growing larger and larger, and the nail upon it +is spreading around it and is growing firmer. The creature, too, is +standing more nearly upon his toes; his legs are getting longer; he +stands higher from the ground, and now has come to be the size of a +hound.</p> + +<p>We can only surmise why this creature should have undergone such a +change, but the presence of flesh-eating animals having the size of a +fox, and presumably of the fox's swiftness, probably tells the story. +The little bands of early horses, pursued by their carnivorous foes, +were slowly modified into swifter creatures. It is not so much that +running made them fast, as that the slow ones were continually being +caught. If this process of constant elimination of the slow members of +any herd is kept up long enough, the group will necessarily develop +speed. As time goes on, of these early horses those which happened to +have longer legs and stood higher upon their toes won in the race, and +handed on their qualities to their long-legged descendants. As the +animal rose upon his toes, the inner toe, corresponding to our<span class="pagenum"><a name="Page_227" id="Page_227">[Pg 227]</a></span> thumb, +was first raised off the ground and rendered useless, while a similar +change came over the corresponding toe on the hind foot. The hard work +of running being done on the latter, this superfluous toe was more +detrimental there than on the front foot, and disappeared, +consequently, more rapidly. In time, however, it also disappeared from +the front foot. Gradually the further elevation of the foot lifted the +toe, which corresponds to our little finger, off the ground, and this +now disappears also.</p> + +<p>With increasing toughness of the grasses, as the climate becomes drier +and the region more elevated, the teeth of the horse are given harder +work. The points begin to spread into ridges and to unite with each +other in such way as to form the crescents, which are later to be so +characteristic of the teeth of the modern horse.</p> + +<p>By the middle of the Tertiary this ancestral horse has risen in height +until he is taller and heavier than a setter dog. Three toes are found +on each front foot. The middle toe is getting constantly more +developed, though the smaller toes are evidently still of use. The +ridges of the teeth are quite crescentic now on the outer side, and +becoming better adapted to the evidently firmer food which the +creature is obliged to eat.</p> + +<p>As we come toward the end of the Tertiary, the de<span class="pagenum"><a name="Page_228" id="Page_228">[Pg 228]</a></span>velopment which had +been all pointing in one direction has advanced very much further. The +creature now would be undoubtedly recognized by anyone as a horse. The +legs are longer and straighter; the middle toe has become the only +useful toe, though on each foot a smaller toe, slender and probably +useless, still hangs on either side. Two similar useless toes to-day +hang at the back of the foot of the cow, which is now walking upon her +two toes, which give her the appearance of carrying a cloven hoof. +That is to say, the first toe on the foot of the cow has disappeared, +the second and fifth hang useless and much diminished at the back of +the foot, while the third and fourth are both well developed and +serviceable in walking.</p> + +<p>The late Tertiary horse has grown to be the size of a burro of to-day, +though probably it was a little more slender. The teeth are quite +horselike, both in shape of the crescentic ridges on their surface, in +the length of the teeth in the jaw bone, and in the fact that the +crinkled edges of enamel on the upper surface are protected on either +side by dentine or by cement. These surfaces, being softer than the +enamel, wore away somewhat more rapidly and allowed the sharp edges of +enamel to stand up in ridges. This plan increases the grinding power +of the teeth.</p> + +<p>With the oncoming of the Era of Man the horse<span class="pagenum"><a name="Page_229" id="Page_229">[Pg 229]</a></span> reaches his modern +splendid development. During the early Quaternary the horse was +perhaps in some of his representatives a larger creature than he is +to-day. Each foot now has but a single toe. The nail has spread around +firmly and heavily, until it has become a splendidly developed hoof, +permitting the animal to travel with speed over firm and often stony +ground. The side toes have disappeared completely from the outside of +the horse's leg, although upon removing the skin it is easy to find +the long splints, which are the remnants of toes, which have not yet +quite disappeared. His heel has been lifted in the air until it is +eighteen inches off the ground, and he is standing like an expert +dancer upon the tip of his toe. The body of the horse thus being +lifted far off the ground, a new development becomes necessary. All +through the growth of the creature the neck and head have been obliged +to lengthen correspondingly. Every animal must be able to bring its +head down to the level of its feet in order that it may drink. Various +animals use different methods to accomplish this result. The giraffe, +with his enormously long legs, has a correspondingly long neck, which +lowers his mouth to the ground. Even with this extended neck the +giraffe's legs are so exceedingly long that he is obliged to spread +his front feet when he wishes to reach the ground with his head. The +elephant has pursued ex<span class="pagenum"><a name="Page_230" id="Page_230">[Pg 230]</a></span>actly the reverse plan. Using his tremendous +head as a battering ram in fighting, and using his enormous tusks both +in battle and in uprooting young trees, a lengthened neck is +absolutely out of the question. Furthermore his front teeth have grown +so prodigiously that they would interfere with his getting his mouth +to water. Accordingly, his nose has lengthened its tip until it +reaches the level of his feet, and this nose becomes to him the main +organ of grasp and of touch. To drink, its end is inserted in the pool +and water is drawn up the nostril. If the animal were to attempt to +draw it all the way back into his throat, it would inevitably strangle +him by getting into his windpipe. Accordingly, when the nose is well +filled with water, the tip of it is inserted in his mouth, and the +water discharged by a quick puff. The horse has taken a method +intermediate between these. It had moderately lengthened both neck and +head in order to get to the ground with its nipping teeth, and thus to +gather the grasses which serve as its principal food.</p> + +<p>The mammalian teeth, while of four kinds, really in most animals serve +but two purposes. The front teeth consist of the incisors and canines, +and are used for biting. The hind teeth, consisting of premolars and +molars, are used for grinding. In the horse, the jaw has lengthened +between these two sets, carrying the biting teeth far forward of the +molars. It is this<span class="pagenum"><a name="Page_231" id="Page_231">[Pg 231]</a></span> gap in the row of the horse's teeth which makes it +possible for us to insert the bit into his mouth.</p> + +<p>Now comes a strange accident into the life of our American horse. +Creatures of the same kin had been evolving in Europe and Africa, but +the developments are more distinctly horselike, it would seem, in our +own country. Then for some reason the horse disappeared completely +from American soil. Doubtless two things happened. First of all, some +of them migrated across a stretch of open country which then connected +America with Asia in the neighborhood of Bering Strait. These +creatures spread first over Asia and then over Africa and Europe, +leaving their skeletons scattered over this enormous stretch of +country. Asses and zebras are still found abundantly and widely +scattered, but the wild horse of to-day is seen only in western Asia. +What happened to those who remained in America we shall possibly never +know. Some surmise that a fly not unlike the tsetse-fly of Africa +killed them out. Perhaps the members of the cat family, which are +steadily growing larger and fiercer, fed on their young if not upon +the older ones, and exterminated them. Perhaps the Glacial period +which followed was too cold for them. But, whatever may have been the +cause these horses died out not only in North but also in South +America, to which country they had spread.</p> + +<p><span class="pagenum"><a name="Page_232" id="Page_232">[Pg 232]</a></span>The old world horse was the companion of man. The skeletons of those +found with early man in the caves of Europe look as if the horse had +been a creature to draw man's burdens and to serve him for food, +rather than to bear him upon its back. Its roasted bones are often +found about the old tribal fires. Upon the discovery of the new world +the Spaniards brought with them to Mexico and to the Mississippi +Valley the horses which carried them in their battles against the +Indians. In the course of these frays many riders were killed and +their horses roamed wild. Slowly they made their way to the western +plains; gradually they became tougher and more wiry; their diminished +hoofs learned to catch more carefully in the rocks of their mountain +home; and the mustang and bronco of more recent years are the +descendants of the little dawn horse, whose dainty skeleton is found +in the rocks over which his later descendants, after a long stretch of +perhaps four million years, are now running.</p> + + + +<div class="section_break"></div> +<p><span class="pagenum"><a name="Page_233" id="Page_233">[Pg 233]</a></span></p> +<h3>CHAPTER IX</h3> + +<p class="chapter_subhead">Evolutionary Theories Since Darwin</p> + + +<p>In considering the value of Charles Darwin's work and its permanent +effect upon the thought of mankind, we must be careful to distinguish +between two phases of his effort. It was his aim to prove two +propositions: first, that there is such a process as evolution; +second, that he had discovered the method by which evolution is +accomplished. Before his time there was no general agreement as to the +fact of evolution. People generally thought the idea absurd, as well +as irreligious. All previous efforts on the part of advanced thinkers +to persuade mankind of the truth of evolution had been nearly without +effect. Among the early philosophers the whole idea was purely +speculative. They made no attempt to prove it, and the conception was +without influence upon the thinking of the ordinary man. This remains +true until the time of Lamarck. This French genius succeeded in +persuading not a few people of the validity of the idea of evolution. +He probably could have convinced many more had it not been for the +hostility of Cuvier.<span class="pagenum"><a name="Page_234" id="Page_234">[Pg 234]</a></span> Accordingly, Charles Darwin's "Origin of +Species" fell upon a world entirely hostile to the idea, when it +thought of it at all. Within fifty years of the publication of this +wonderful book, probably the entire scientific world is agreed that +evolution, in some form or other, is the undoubted solution of the +mystery of creation. The materialist may think of it as a mechanical +process relentlessly working itself out without design or purpose. The +theist will accept it as the plan by which Eternal Power steadily +works. The devout Christian or Jew will see in it God's method of +creation. The idea of development has penetrated every science that +has to do with animals or man. It is even beginning to influence such +inorganic sciences as Physics and Chemistry. We now hear of the +evolution of the elements, and the evolution of forces. The world has +been persuaded that evolution is true, and this is primarily the +result of the work of Charles Darwin. It is astonishing that so great +a revolution should have come in so short a time.</p> + +<p>The other phase of Darwin's work was his attempt to find the agent +which is bringing about the actual transformation of animals and +plants. As we have seen in the preceding chapters, it was his idea +that natural selection was the efficient agent which constantly +eliminated all unfit variations, leaving only the best to carry on the +work of the world and to repro<span class="pagenum"><a name="Page_235" id="Page_235">[Pg 235]</a></span>duce their own fit kind. Many +biologists since his time have doubted whether unaided Natural +Selection will account for the constant advance in organisms. This is +the part of the work which is often seriously questioned.</p> + +<p>Weissman and his co-workers have contended that this unaided principle +will serve. Most biologists have asked for some more efficient cause, +and assert that selection does not account for the appearance of +variations, but only for their preservation, and that any valid theory +of evolution must show how variations originate. It is chiefly in this +respect that Darwin's work has failed to satisfy many later +biologists. When we hear a scientist speak of Darwinism as being dead, +this is what he means. He does not think evolution false, but believes +that Natural Selection is not sufficient to account for evolution. +There are three main difficulties involved in Darwin's theory. The +chief defect lies in the fact that selection cannot originate +varieties. In all his earlier works Darwin simply accepted variations +as he found them. He was content to say that all species varied +constantly, and in every direction. He gave no theory to account for +variation. Whenever he took measurements of the dimensions of any +large series of objects of the same kind he found these measurements +to vary, apparently, in all directions. Upon the facts of these +variations,<span class="pagenum"><a name="Page_236" id="Page_236">[Pg 236]</a></span> and without accounting for them, he built his own theory +of evolution. He realized his weakness, and acknowledged it in his +book. He probably did not anticipate how insistently later biologists +would demand an explanation that would account for this variation. In +his later work, responding to this criticism, Darwin originated a +theory which he called Pangenesis. He believed that when an adult +animal had responded to his environment and acquired a new character +he could transmit this character to his offspring. At that time no one +doubted this fact. The whole theory of Lamarck was based on the +assumption that this could be done. Darwin suggested that every organ +of the body threw off minute particles, which he called pangenes. +These little bodies, carried by the blood, were taken up by the egg +cells or sperm cells, and the latter cells determined the future +development. Consequently, the character of the new individual was +determined by the parental pangenes. In this way the gain acquired by +one generation could be passed on to the next. This theory was purely +speculative. He never pretended that there was the faintest +corroborating evidence visible to the microscope in the organ, in the +blood, or in the germ cell. It was not an accounting for what is, but +for what it seemed possible to him might be.</p> + +<p>This theory of Pangenesis, in the shape in which<span class="pagenum"><a name="Page_237" id="Page_237">[Pg 237]</a></span> Darwin promulgated +it, has dropped out of consideration almost entirely. DeVries of +recent years has revised it, but with distinct modifications, and most +biologists pay no attention to it.</p> + +<p>There is a school of biologists, headed by Weissman, who have come to +be known as Neo-Darwinians. These men have insisted that Natural +Selection, if properly understood and developed, is quite sufficient +to account for the fact of evolution, including the appearance of +variations. Weissman himself is a microscopist of more than common +skill. He is thoroughly accomplished in the most modern methods of +killing, fixing, staining, and mounting. This worker's acquaintance +with the intimate structure of the cell is probably as great as that +of any other man in the world. Weissman asserts that he has seen +inside the nucleus all the machinery necessary to explain how the +father hands over his qualities to his children. He insists, equally +strongly, that this process is such that no father can hand to his +child any qualities which he himself did not have at least in +potentiality at his birth. Everything the individual acquires during +his lifetime is his own possession, which he may use and develop to +the utmost extent, but it dies with him. His children, born after he +possesses it, can no more inherit it than those born before. Weissman +expressed this in his famous statement that "There is<span class="pagenum"><a name="Page_238" id="Page_238">[Pg 238]</a></span> no inheritance +of acquired characters." The biological world has had no shock equal +to this since Darwin's time, and there are few other questions to +which scientists to-day return with such constant vigor.</p> + +<p>If what Weissman says is true, that no variation or development which +comes to an animal during his lifetime can be transferred into his own +germ cells and handed on to his children, then it becomes evident that +we must find some cause of variation that acts within the germ cells. +This is the difficulty which Weissman meets. He says that there are +small particles in the nucleus of each cell; that these particles +which he calls determinants decide the form and the course of +development of that cell; that when that cell divides to produce +another cell it gives to this other cell one-half of each determinant. +As a result the second cell grows to be like the first. This tells us +why offspring are like their parents. There is nothing in the theory +thus far to show us why offspring are not exactly like their parents. +In other words, there is no accounting, thus far in the theory, for +variation. When the biologist studies carefully the history of an egg +while it is being formed, he sees that at one stage in its development +it throws away not one-half of each determinant, but one-half of the +determinants. When an egg does this, it deliberately casts aside +one-half of the possibilities of its own de<span class="pagenum"><a name="Page_239" id="Page_239">[Pg 239]</a></span>velopment. This throwing +away is quite as effective for all its descendants. Any ancestral +quality now lost is lost from the line forever. In the formation of +the sperm cell set free by the male a similar throwing away of +one-half the characters has taken place. The egg cell and the sperm +cell fuse together. There are as many possibilities now as there were +in either parent, but not all the potentialities of both parents. Half +the possibilities of each have been thrown away, and hence cannot +appear in the offspring. By this constant process we get, in every +generation, new combinations of qualities. This is the main cause, +says Weissman, for variations.</p> + +<p>There is, however, another possible cause. Each cell has enough +determinants in it for many individuals, and it seems to be more or +less a matter of accident which qualities shall come out. It has been +suggested that as an egg lies within the gland, a blood vessel may +bring blood to it in such way that a determinant, lying in a certain +position in the egg, may get the richest supply of blood, and hence +develop at the expense of the less nourished determinant. By these two +methods variation comes into an animal's life, if Weissman and his +school are to be believed.</p> + +<p>This is a serious blow, if true, to many theories of evolution. The +great mass of evolutionists still feel<span class="pagenum"><a name="Page_240" id="Page_240">[Pg 240]</a></span> that somehow there is an +influence by which the environment produces variation. How the +influences of the surrounding world can get down into the body of the +parent and affect the egg is unknown. This is freely confessed by +every biologist. All are agreed that Weissman's work has made us +cautious, and prevented our lightly accepting a belief in the +influence of the environment. Yet it is felt by many that slowly and +gradually, in the long run, the germ is affected in the same manner as +is the body of the parent. In other words, even those who are not +followers of Weissman, have accepted the idea that there is little +inheritance of acquired characters. Yet they return to the belief that +somehow, in some way as yet unexplainable, the main cause for +variation in animals lies in the situation in which they live, and +tends toward better adaptation to that situation.</p> + +<p>Whether men with this conviction are merely reactionaries whose +confidence is returning, or bold thinkers whose views will ultimately +prevail, time alone can tell.</p> + +<p>A second strong objection was brought against the theory of Natural +Selection. Darwin declared that small variations in favorable +directions are selected and become the starting point of new and +better things. It is soon seen, however, that the effect of unaided +Natural Selection would be but to mix new<span class="pagenum"><a name="Page_241" id="Page_241">[Pg 241]</a></span> departures with the old +forms, and soon swamp out any progressive tendency. Whenever a genius +appeared, instead of finding a corresponding genius with which to +pair, it mated with the average of its own species. Hence its +offspring were nearer the average than it was, and their offspring +still nearer. Thus whatever advantage the genius originally possessed +gradually sank into the common level.</p> + +<p>It was Moritz Wagner, a German naturalist, who first insisted that if +favorable variations were to amount to anything these possessors must +not only mate with others of their same kind, but must also be +prevented from mating with the old average group. Accordingly, the +belief arose that, under ordinary circumstances, variations returned +to the common level. Wherever a varying group became separated by any +barrier from mating with the rest of its species, and had only its own +kind to pair with, a new species sprang up. This barrier might be a +desert, or an impassable mountain range, an arm of the sea, or +anything else that the animal could not, or would not, cross. Isolated +in this way, the little group that had an advantage in a different +direction could develop its tendencies, and a new species would be +made of what had been previously only a geographical race. In this +matter of geographical isolation Wagner is very strongly supported by +the<span class="pagenum"><a name="Page_242" id="Page_242">[Pg 242]</a></span> American zoölogist, David Starr Jordan, who believes that no two +closely related species of animals ever occupied the same geographical +area. Both Wagner and Jordan are ardent admirers of Darwin and his +theory of natural selection, but both believe that it is necessary to +add the idea of isolation in order to make natural selection +effective.</p> + +<p>George John Romanes, a British naturalist, has added to Wagner's idea +of isolation, the expanded conception that there may be isolations +that are not geographical. For this phase, Romanes has coined the term +physiological isolation. Something in the structure or habit of the +animals with the new variation prevents them from mating with the +older type. Occasionally it is a difference in the structure of the +reproductive organs themselves. This, however, is not the only +possible divergence. The mating season in one group may come earlier +than that of the other, or may come during the day, while the main +group is in the habit of mating at night. Anything which keeps some +members of a species separate in their mating from the rest, will +result in the course of a longer or shorter time, says Romanes, in the +formation of a new species.</p> + +<p>A third great objection was raised against Darwinism. The theory said +that only useful variations were selected by nature. It was asserted +by objectors<span class="pagenum"><a name="Page_243" id="Page_243">[Pg 243]</a></span> that the earliest beginnings of any variation must be +too slight to be useful, or as the term went, to have selective value.</p> + +<p>It has been noticed by a number of naturalists that certain animals +seem to carry the development of a peculiarity altogether too far. It +is seen for instance that in the Irish Elk, which has for some time +been extinct, the horns were so enormous as to be a source of danger +rather than of assistance to their owner. It was said that the +tendency to produce heavy horns had gained, as it were, a sort of +momentum, and that this impulse had carried the development beyond a +safe limit. The Irish Elk became extinct because his horns were too +heavy. During the Mesozoic period the reptiles grew too large. They +seemed to have carried size to a point at which it became a danger +instead of a help. They completely passed out of existence, leaving +behind them only very much smaller reptiles.</p> + +<p>Eimer, of Germany, has based on facts like these his theory of +Orthogenesis. He says that variations in animals are not indefinite +and in every direction, but that they follow along clear and definite +lines. These lines, in the case of the elk and of the Mesozoic +reptiles, developed too far, but ordinarily the effect of such a +tendency is distinctly beneficial to the animal. It particularly +assists in carrying on for<span class="pagenum"><a name="Page_244" id="Page_244">[Pg 244]</a></span> a time the variations which have not yet +become useful to the animal. It has always been difficult on Darwinian +principles to understand how the beginnings of the useful variations +could be selected before they were strong enough to be of actual value +to the animal. This tendency to variations in certain directions +instead of at random would account for such early development. This +theory of Orthogenesis has not figured very strongly in the history of +the movement, but it recurs at intervals.</p> + +<p>Both in America and France there is a constant tendency on the part of +zoölogists to return to the Lamarckian idea that it is the use of an +organ that develops it, its disuse that makes it fade away. This is +undoubtedly true of the individual, and although Weissman insists that +it is useless to the species as a whole, many zoölogists are slow to +relinquish entirely the idea that somehow these favorable developments +become reproduced in the offspring.</p> + +<p>Professor Cope, the American paleontologist, was a strong believer in +the effect of activity, both upon the individual and upon his +descendants. He believed that the insistent beating of the foot of an +animal upon the hard soil of the drying Tertiary plateau, had +influenced the production of a firmer nail, which spread around the +entire end of the toe and made the hoof of the ungulate. He believed +that the use<span class="pagenum"><a name="Page_245" id="Page_245">[Pg 245]</a></span> of the teeth in grinding produced a stronger and better +molar tooth, and that the offspring shared in this advantage. Since +Weissmann's time, however, every Lamarckian feels it necessary to +suggest some method by which the altered body of the parent can +produce modifications in the germ plasms from which the young are to +spring. One of our later biologists begins to talk of some effect +comparable with wireless telegraphy or induced electricity. He +believes that organs in the adult, not necessarily by direct action, +but by action from a distance, may alter the germ. Of this, there is +no proof at present. Others have suggested that just as the ductless +glands pour into the blood chemical substances which materially affect +the growth and development of other portions of the body, so similar +enzymes, or other chemical substances, may be sent into the blood, +which subsequently bathes the germ cells of the coming generation and +produces the change. But of this, again, there is no proof. We may +believe that acquired characters are transmitted, but we certainly do +not have a very clear idea as to how it can be done.</p> + +<p>One of the strongest objections to Darwin's idea of evolution by +natural selection of small and favorable variations, is that the +process is too inconceivably slow to account for the enormous progress +which has been made. The answer has always been that our<span class="pagenum"><a name="Page_246" id="Page_246">[Pg 246]</a></span> observation +ran back so short a time that we really have no clear idea of how +rapid evolution may have been. Again, it has been answered that +transitional geological periods, in which there is much change in the +physical geography of a country, will produce more rapid evolution +than we at present are experiencing.</p> + +<p>Hugo DeVries, of Amsterdam, believes he has found the answer to this +difficulty. Outside of his botanical garden an American species of +Evening Primrose had run wild. In looking over a number of these +plants he found, every here and there, certain peculiar members of the +species. They differed noticeably to the practiced eye from the rest +of the group. When they were planted and crossed with each other, and +the resulting seeds were again planted, the peculiarity remained +constant in all the members of the collection. Here then we have a +true variation, not large in amount, but at the same time quite +definite, and which from the first remains true. Here are the +beginnings, says DeVries, of new species. They are true from the +first; they can live among other members of the species and still come +true; they do not need isolation, at least in Wagner's geographical +sense. These forms DeVries calls mutations. It is his thought that a +species may run along uniformly for a long time when, from some cause<span class="pagenum"><a name="Page_247" id="Page_247">[Pg 247]</a></span> +which he has not determined as yet, instability comes into the species +and it varies in quite a number of directions. Each of these +variations may be the starting point of a new species. DeVries +believes that he has at least half a dozen mutants of his new Evening +Primrose.</p> + +<p>This theory of Mutation has been eagerly seized upon by many +botanists. The zoölogists have not accepted it quite so +enthusiastically. If this is the chief method by which species +transform, it seems strange that we do not find more mutations than we +do. Perhaps we do not look carefully enough; perhaps we shall find +them a little later. Just at present it seems premature to believe +that all evolution is by mutation, although quite possibly some of it +is. The main apparent advantage of mutation is that it hastens the +time in which a new species may arise.</p> + +<p>There are certain difficulties which run back into the problem, and +which must first be reasonably solved before a clear understanding of +the idea of evolution is possible. The first of these is as to the +nature of life. What is life? The reply of the biologist will probably +be that so far as its material side is concerned, it must be answered +in terms of physics and chemistry. As to any side not material, if it +have any such side, science says that the chemist can have nothing to +say. The chemist may have an<span class="pagenum"><a name="Page_248" id="Page_248">[Pg 248]</a></span> opinion of his own based on some other +ground than his chemistry, but so far as he is a chemist, he has no +opinion. The chemical side of life is being very carefully and very +fully investigated. We are certainly being brought nearer to the +borders of the living substance. We are rapidly gaining fuller +knowledge of the physical and chemical processes which constitute +life, or with which life is always associated. If we gain this +knowledge we shall be in better position to solve many of our other +problems. Even then there is a problem which preceded and which will +possibly always defy solution. How did life originate? Has it +developed out of chemical and physical activities which we know as +heat, light or electricity? If so, what were the conditions under +which it developed? If we understand the nature of life, and the +conditions under which it developed, we may be able to produce it at +will.</p> + +<p>A few scientists may hope dimly that this will be attained. I suspect +a great majority believe it to be impossible, and that the question as +to whether life evolved upon this planet, or this planet became +infected with life through meteoric dust from some other center, will +forever remain an unsolved problem.</p> + + + +<div class="section_break"></div> +<p><span class="pagenum"><a name="Page_249" id="Page_249">[Pg 249]</a></span></p> +<h3>CHAPTER X</h3> + +<p class="chapter_subhead">The Future Evolution of Man</p> + + +<p>The disturbance of mind created by the publication of Charles Darwin's +"Origin of Species" would have amounted to nothing if the theory had +been applied to the lower animals alone. Few people would have +disputed that a cow and a buffalo had descended from the same +ancestor, or that monkeys and apes were of a common blood. The whole +theory would have been looked upon by those outside the biological +world as entirely an academic question, in which they had little +concern, and less interest. But within this century the scientist has +so persuaded the world of the unity underlying the activities of the +universe, that so soon as a principle is established men begin to run +it out to the very end. Everyone knows perfectly well that if it could +be proved that the dog and the horse had a common ancestor, still more +if it could be made apparent that the dog and the frog and fish had +sprung from the same stock, then there could be no question of what +would be the final application of the theory. Man himself could be no<span class="pagenum"><a name="Page_250" id="Page_250">[Pg 250]</a></span> +exception to the law. So the battle dropped at once upon this most +interesting point, and around this center the contest has waged.</p> + +<p>What is the origin of man? Who are his ancestors? As soon as we ask +the question there is no doubt whatever as to the answer, if we accept +the principle of evolution. Our only means of judging relationship +between animals is by the similarity of their structure. As soon as we +come to examine the other creatures even in the most cursory fashion, +there is only one group which in any close degree resembles the human +species. Our nearest relatives among living animals must undoubtedly +be the apes. Some little distance farther away stand the monkeys, and, +structurally speaking, there is more difference between a monkey and +an ape than there is between an ape and man. The gap between man and +his relatives of this group, known as the primates, is a mental, not a +physical one. While his brain and his mind have developed far beyond +theirs, the rest of his body is comparatively close to that of an ape.</p> + +<p>Probably no one can face the possibility of his being descended from +creatures not unlike the ape, without feeling a stirring sense of +repugnance. The least aristocratic of us hesitates to name in the line +of his ancestry creatures so unlike himself as the members of this +group. It seems to us impossible<span class="pagenum"><a name="Page_251" id="Page_251">[Pg 251]</a></span> that we should have descended from +creatures as lowly as they. If evolution is true, these are among our +near ancestors. Back of the group of primates lies a far less +developed set of insectivorous animals, behind them the reptiles, +behind them the fishes. When we get back this far we are less certain +but most probably the worms take up the story. So our ancestry runs +back to the very beginning, when it originated in the one-celled +animals which are also the ancestors of all the rest of the animal +world. If we are inclined to deny our ancestors in the trees, what +shall we say of our forefathers in the seas?</p> + +<p>The question of course is not to be decided by our likes or our +dislikes. If the evolution of man is true it will not make it less +true because the process is not to our liking. It is our part, if this +be the truth, to accept it as we do any other truth. Surely those of +us who are moral of thought are not willing to disbelieve a truth +because it is unpleasant.</p> + +<p>The newness of the idea is the chief reason for our dislike of it. +This lowliness of origin should not be distasteful to us. Nothing +about Abraham Lincoln seems to us more wonderful than that a man who +towered head and shoulders above his generation, indeed above most +generations of men, in his fineness of life, in his nobility of +purpose, in the integrity of his aims, should have been of +ex<span class="pagenum"><a name="Page_252" id="Page_252">[Pg 252]</a></span>ceedingly humble extraction. It only adds to the glory of his later +achievements that he should have lived in a cabin, have spent his +young manhood splitting rails and running a flat-boat, and have gained +his education almost unaided from a few books and much meditation in +front of a log fire.</p> + +<p>That the greatest military General on the Union side of the Civil war +should have been the son of a country tanner, and as a boy, not +over-shrewd in the matter of bargains, adds to the glory of his later +life. The simplicity of his childhood gives new luster to the power +with which he led the forces of a nation to victory, and then went to +a battle no less noble in his long fight for honor while suffering +from disease and approaching death. Why then should we feel that such +beginnings in the lower world are too humble for man? Why do we think +his present superiority diminished by his lowly origin? Why can we not +see that precisely the reverse is true? The more humble the level from +which he sprang the more gloriously creditable is his present +position. Instead of being ashamed of having risen from the brute, it +should be the glory of man that he has so sprung. His chief +superiority lies in the fact that while they have remained where they +are, he has so completely outdistanced them as to have placed a gap +between himself and them that seems almost<span class="pagenum"><a name="Page_253" id="Page_253">[Pg 253]</a></span> impassable. Furthermore, +if man with his present glory of intellect and of moral impulse, has +sprung from a creature whose superiority to the ape lay chiefly in its +potentialities, then it does not yet appear what he shall be. We can +judge the future only by the past. Through the long ages the +development has been very slow. Through the last hundred thousand +years the development of man has been wonderfully rapid, compared with +what went before, though it seems slow enough when we look at it from +the standpoint of our historical and traditional reports. But with +this added impulse, this rapid improvement that has come with the +development of mind instead of muscle, of tooth and of claw, we have +every promise of an evolution that shall far surpass anything that has +yet come. To-day our leaders are way beyond the average of the mass. +Who shall doubt that in a not too distant to-morrow, the masses shall +be where the leaders of to-day now are. We shall not then have reached +a dead level of superiority. Our leaders will have moved on as rapidly +as have the masses, and will be as far ahead of them then as they are +now. It shall be their work to apprehend new virtues, and to work them +out in their lives. The masses, seeing the beauty of the lives of the +leaders, recognizing in those lives the revelation of the divine power +which they have apprehended, will hunger to<span class="pagenum"><a name="Page_254" id="Page_254">[Pg 254]</a></span> learn of them and to lead +lives like theirs. To this process who shall set an end? The advance +is slow, as in all evolution; but anyone who wishes to do so may +easily detect the direction of the current.</p> + +<p>The evolution of man's physical frame probably has nearly ceased. +Gradually organs that are useless to him are passing away. Slowly his +hands are becoming more delicate and refined and skilled. But his +evolution has begun to work itself out on entirely other lines. We +sometimes hear that the men of the past were the full equivalent of +the men of to-day. Scholars like to tell us that the population of +Athens was finer in quality than any population that has existed +since. We must remember that group after group of men may be expected +to specialize intellectually and fail to develop morally and +physically. Under these conditions this little branch of the human +race runs through its forced flowering and comes to an end. With the +study of history and the earnest investigation of these lives of the +past, new possibilities arise within the human family. The next race +that flowers may take longer to decay because it understands better +the weaknesses that carried away the preceding civilization. In time +there will arise a civilization that understands the past. A whole +people will some time realize that intellectual development alone will +not save it, or Athens<span class="pagenum"><a name="Page_255" id="Page_255">[Pg 255]</a></span> would have lasted; that moral development +alone will not suffice, or Judæa had been permanent; that physical +development will not serve, or Sparta would stand to-day. Some day +there will arise a nation that will see to it that every intellectual +advance is accompanied by an equivalent moral and physical advance. +When this time comes we shall have a race which can survive. Are we to +be that race? The sins of man are generally the dregs of his brute +ancestry. Bestiality of life was once common enough to attract no +attention. Kings and nobles were not supposed to be clean so long as +they confined their bestial relations to those below them in rank. +Gradually men are becoming ashamed of uncleanness in life. Some day +there will be no difference so far as purity of life is concerned, +between the two who present themselves at the altar asking the +blessing of God on their union.</p> + +<p>If anyone doubts that English speaking people are becoming cleaner of +life he needs only to consult the literature of the past. No one +dreams of finding fault with Chaucer because his stories related in +the company of men and women often would not bear such telling to-day. +Shakespeare, with all his wonderful genius, needs expurgating if one +would read him aloud comfortably to a mixed audience. And these are +the shining stars. When we drop<span class="pagenum"><a name="Page_256" id="Page_256">[Pg 256]</a></span> below them, the literature of their +time becomes nearly impossible to read. Fielding and Smollett and +Stern helped to build up the English novel, but the stories they tell +speak of the grossness of their time in language that is unmistakable. +We are by no means clean to-day. A fair proportion of our novels leave +much to be desired. The stage is the scene of much we could wish to +see cleaner. Above all this grossness there towers a sweetness and +beauty of thought, and an earnestness of purpose, a sincerity of +effort, which makes the present time fuller of moral purpose, fuller +of the desire to be clean and to help others to be clean, than graced +any previous period in the history of either England or America.</p> + +<p>Under the change from country to city life man has suffered. Here too +evolution is necessary. City life tells hard on the second generation +and nearly destroys the third; but we have come to understand the +difficulty and are fast remedying it. It is more than possible that +the next generation will see such changes in the life of the worker in +the great center, as shall effectively stop the physical deterioration +that has come to the city dweller. God grant that modern civilization +has had teaching enough and learned its lesson well enough. God grant +further that we may give over slaughtering our most ambitious and +vigorous young men in battle to settle<span class="pagenum"><a name="Page_257" id="Page_257">[Pg 257]</a></span> questions which battle can +never settle. God grant that we have come to a turning of the ways +where the life of men, women and children, no matter how humble their +station, shall stand higher in value than the profits of any +commercial venture. God grant that we will soon be firm enough to +declare that a business which can only live by sacrificing the health +and strength of the workers must be counted an unprofitable business, +and be allowed to cease. God grant finally that the American people +may learn from the past to guard against a like fate in the future; +that here may be the people whose strength, intelligence and +uprightness shall lead the world; not for the sake of exceeding the +world, but with the high mission of setting to the world an example of +what can come to a vigorous, free and God-fearing people.</p> + +<p>In the early history of the evolution of man the struggle almost +always concerns the individual. Gradually the family comes to be the +fuller unit. Only that is success which leads to the success of this +higher group. After a time the family broadens to the tribe, and then +the tribe to the nation. The evolution of social institutions is at +present going on at an enormously rapid rate. Throughout the civilized +world democracy is coming to its own. Even where the form of monarchy +still prevails, the sub<span class="pagenum"><a name="Page_258" id="Page_258">[Pg 258]</a></span>jects of the monarch are having more and more +rights. The people of England are surely as free as are the people of +the United States. Increasingly all forms of government will secure +for all their subjects, no matter what their station in life, a fair +share of the general prosperity. In this field, human evolution is +perhaps more rapid than in any other.</p> + +<p>Any individual human being is a network of traits and peculiarities. +He has all the ordinary attributes of humanity, but to the whole +complex he gives an individual peculiarity which is totally his own. +Where did he get his qualities? In the earlier times the fairies were +supposed to have blessed him or cursed him in his cradle. A later age +saw in the stars the rulers of man's destiny. He was jovial, or +saturnine, or martial, depending on the planet which was in the +ascendant at the time of his birth. Now we know "it is not in our +stars but in ourselves that we are underlings." Everything a man is +comes to him from within or from without; from nature or from nurture; +from his heredity or from his environment. From our ancestors we get +all the possibilities of our lives. To a certain extent we are slaves +to our heredity, but not by any means to any such extent as to make us +hopeless, unless our heredity is miserably bad. To the great mass of +us come larger potentialities than we ever develop, and such<span class="pagenum"><a name="Page_259" id="Page_259">[Pg 259]</a></span> +possibilities of degradation as, fortunately, few of us ever reach. +Within an enormously wide range, man is the architect of his own +fortune. Only such traits develop as find a stimulus in the +environment. Accordingly, a very large proportion of the development a +man may achieve depends upon the circumstances under which he is +placed, or, what is far more to the point, in which he may place +himself. Man is not the blind sport of a relentless destiny. It is his +to choose his environment; it is his to modify his environment when he +cannot leave it. To an extent which no other animal has ever +approached, man is the arbiter of his own destiny. A hypothetical ass +may stand helpless between two equidistant bales of hay, but no human +being is ever so helpless a sport of his environment. As it is, he may +drift or he may rove as he pleases. To one man the current may be +stronger than to another. There may be now and then a child so +feeble-minded as to be unable to decide the course of its own life. It +will not be long before society will see to it that such a life leaves +behind it no strain cursed with its fatal weakness. In this effort to +advance, man has all the advantage that comes from concentrated social +effort. No man may live to himself. To every man in our community who +desires it, a helping hand will be stretched. Often a hand will be +stretched to him<span class="pagenum"><a name="Page_260" id="Page_260">[Pg 260]</a></span> and he will be steadied whether he will or not, +until his own will reforms itself and gains the mastery.</p> + +<p>Inasmuch as all that is in man comes from his environment or from his +heredity, the only way in which the race of men can be advanced is by +improving their environment or by bettering their heredity. The first +of these is the province of the sociologist; the second that of the +eugenist. The sociologist has for some time been giving his careful +attention to the improvement of the environment. In every large city, +a man must build for himself a house fit to live in, if he build it at +all. Whether he erects it for himself or for another makes no +difference. Society will no longer allow him to build a home which is +a detriment to the one who lives in it. Not only must he make himself +a decent home but he must keep it in decent condition. The community +will not allow him to endanger his own health, or that of his +neighbor, by an insufficient method of attending to his garbage, or by +a lack of ordinary cleanliness. If he will not clean his premises +himself, the law sees to it that they are cleaned for him. Already we +are beginning to understand that no man has a right to employ another +man or woman or child at wages which are not sufficient to maintain +the one thus employed. The wages of many people are exceedingly +meager, notably those of women and children. He<span class="pagenum"><a name="Page_261" id="Page_261">[Pg 261]</a></span> can read but ill the +signs of the times who does not foresee an early end to the exploiting +of the labor of these helpless creatures. Humanity has determined +firmly that these things must pass, that the young child must not +labor long or hard, that a woman must not be taxed beyond her +strength. Already in England there is a partially successful movement +which will doubtless spread to this country to provide that a woman be +granted a little time before and after the birth of her child during +which she shall not be allowed to suffer because her power to earn a +wage is temporarily gone. These things cannot fail in the long run to +strengthen the people. They strengthen chiefly the present generation. +The blight of the fact that acquired characters cannot be transmitted, +meets us here. This improved environment can only slowly, if at all, +improve the race, and every effort made in this direction must be +repeated with each generation.</p> + +<p>Under such circumstances is it to be wondered at that the eugenist is +hoping to raise the strain? Any improvement he can bring about is not +only valuable for the generation in which it comes but is carried on +into the generations which follow. This is the hope that strengthens +and sustains him in his effort. The science of eugenics is so new, so +little is surely known concerning the transmission of human +characters, that<span class="pagenum"><a name="Page_262" id="Page_262">[Pg 262]</a></span> no one is able as yet wisely to say what course is +to be pursued in improving the race. But the problem is so interesting +and its outcome so overwhelmingly important that men will never cease +striving to know, and may, before many years, begin wisely to guide us +in our efforts to provide a finer stock.</p> + +<p>Heretofore our efforts at improving the strain have been confined to +cattle, chickens and plants. An almost unalterable repugnance rises as +soon as we speak of improving the human strain. Visions, if not +stories, start up at once, of experimental matings of human beings, +and of all other unspeakable abominations which no decent man expects +to happen or even wishes to attempt. If there is one thing in human +society the value of which has been demonstrated through the unending +ages, it is the monogamic marriage. All ideal workers must point to +the life-long union of a strong, vigorous, clean-minded and +clean-lived man with a similarly fine, strong, clean-minded and +clean-lived woman. Such an ideal may be slow in its attainment, but he +aims too low who aims to secure anything less than this. The long +struggle out of bestiality into pure monogamy has been so slow, so +gradual, so noble in its attainments, and is still so far from +perfection, that it would be an inconceivably stupid blunder to let go +a single point that has been gained. Whether<span class="pagenum"><a name="Page_263" id="Page_263">[Pg 263]</a></span> divorce shall be allowed +to remedy a mistake may be a matter of dispute, but at best it is a +bad remedy for a mistake that should never have been made. No ideal +society could ever consider divorce as any permanent portion of its +activities. Children are not like cattle. It is not simply a question +of their being brought into the world sound and strong. Their long +infancy which in the biological as well as in the legal sense, lasts +until they are grown up, should be spent in surroundings which can +minister, by example and precept, to moral and intellectual +development. Surely no such end can possibly be attained when man and +woman mate lightly, to part quickly.</p> + +<p>At first sight it would seem a wise thing to require health +certificates for those who would be married. I doubt not the Chicago +Bishop who declined to marry his parishioners except under such +conditions, will exert a beneficial effect upon the country by the +attention he thus attracts to the subject. It would be a bad day for +the city if all the clergy and all the other authorities who are +authorized to solemnize marriage should take this step. We have not +yet arrived at such a stage of development that a marriage certificate +is essential to mating, and a restriction of this sort would simply +mean that there could be no legitimate union except of those in strong +health. To the burden of ill health would be added<span class="pagenum"><a name="Page_264" id="Page_264">[Pg 264]</a></span> the still worse +handicap of an illegitimate parentage, with all its bitter train of +scorn and shame. Accordingly, it must be possible before the law for +those who are not thoroughly vigorous to marry. But, year by year, we +may come nearer accomplishing a finer mating by the aims and purposes +we foster in the growing generation. Marriages will never be worth +while when they are not freely entered into by the contracting +parties. Choice must be free and unrestricted if it is to last for +life; but this does not mean that it must be unguarded. It would be +bitter folly for parents to leave to their children, without attempt +to influence or restrain, the making of their marriages. The mating of +our children must be inspired, not directed.</p> + +<p>There is one taint from which society has the right and the duty of +freeing itself, so far as in its power lies. This is the taint of +feeble-mindedness. Of all the calamities that can befall a human +being, feeble-mindedness is, perhaps, the worst. From most misfortunes +it is possible to recover; with most of the rest one may exist without +detriment to the race. To be feeble-minded simply means to hark back +to the level of our animal ancestors, without regaining their power to +guide life. The animal is provided with a bundle of instincts which +tell him what to do in all the ordinary emergencies of life. The +hu<span class="pagenum"><a name="Page_265" id="Page_265">[Pg 265]</a></span>man species, in its development, has lost a large portion of its +instincts, and has gained, instead, the power of intelligent choice +and the ability to learn by imitation. When these drop away, man +without his instincts or his intelligence is more helpless than the +brute. Students of sociology are making clear to us that a large +portion of the criminality of the world, much of the looseness of +life, and a large part of the alcoholic excesses are due to this taint +of feeble-mindedness. Recent investigations have made it clear that +one feeble-minded family in a community may, in the course of years, +poison the life of an entire state. The Jukes family in New York, the +Kallikak family in New Jersey, have shown the awful possibilities of +descent from a single feeble-minded ancestor. Prisons, almshouses, and +houses of shame owe their population in no small degree to this bitter +curse. It will not be long before society will learn to protect itself +against such poisoning of the human stock. Nothing is more clear to +the investigator of this subject than that the one overwhelming cause +for feeble-mindedness is feeble-mindedness in the parentage.</p> + +<p>There is one type of mental weakling, known as the Mongolian idiot, +which may arise right out of the heart of an apparently sound family. +But the number of these is comparatively small. The num<span class="pagenum"><a name="Page_266" id="Page_266">[Pg 266]</a></span>ber of +feeble-minded, who are feeble-minded because of their heredity, is +dishearteningly and astonishingly large. Every attempt to examine +large numbers of school children shows a sickening proportion of those +who are distinctly feeble. Every little community seems to have its +boy or girl who is what is known as silly. Such people rarely live +long lives without leaving behind them feeble-minded children, no +small proportion of whom are likely to be illegitimate. Against this +fouling of the stream at its source, society must protect itself. +Legislators revolt at the somewhat inhuman but certainly safe method +of surgically preventing the possibility of the feeble-minded becoming +parents. It would be more creditable and just as effective if society +would take upon itself the tremendously expensive task of caring for +all its feeble-minded in institutions during their entire life. The +cost would be large for a generation, but would rapidly diminish and +eventually become small. It certainly would be the humane way. These +people in good institutions are by no means unhappy. Within the limit +of their capacities they can do many things. Wise management usually +will secure from them labor enough of wholesome and simple kind nearly +to pay for their own support. Nothing could be better for them than to +till the soil, care for the cattle, tend the chickens, and, in<span class="pagenum"><a name="Page_267" id="Page_267">[Pg 267]</a></span> this +way, provide very largely the materials on which they are fed. How +this problem shall work out, time only can decide. With it once worked +out, there is no doubt that the level of humanity will be distinctly +raised. No other one feature in the program of eugenics seems more +absolutely hopeful than this.</p> + +<p>In several of the states of the Union it has recently become the +practice to remove the possibilities of parenthood from certain +classes of criminals. The purpose of this is clear and benevolent. +Society has a right to prevent the oncoming of new generations of +foreordained criminals. Underlying the practice is the theory that the +children of criminals are born criminals. It is far from likely that +this is the case. Criminality may be due to a wide range of causes. If +the criminal is one of those actual born degenerates whose whole +mental and physical make-up is so defective that nothing but +criminality can be expected of him, then we have a case in which it is +clear that society may, and should, remove the possibility of having +more generations of the same kind. Probably only a moderate proportion +of the criminals in our jails and penitentiaries belong to this class. +Doubtless a distinct majority are criminals more through environment +than through heredity. Born of average ability, or more, these people<span class="pagenum"><a name="Page_268" id="Page_268">[Pg 268]</a></span> +have been criminals simply because they were reared among criminals, +because their surroundings were such as to lead them away from habits +of industry, while they must live. These people were not bolstered by +society, or the church, into a life of self-respect and self-help. +Under these circumstances they fell into evil ways. There is nothing +defective in their mental or physical make-up, that need appear in +their children. If these children are removed from contact with the +criminal class they stand every chance of being as vigorous, as +intelligent, as upright as the average of the community.</p> + +<p>At the recent Eugenics Congress in London one of the speakers +expressed a preference for the son of a husky burglar over the son of +a tuberculous bishop. This is doubtless quite correct, but why should +the bishop be tuberculous? The truth of the matter is, the reverse is +more likely to be the case. Personally, I should prefer to be the +offspring of a husky bishop. In dealing with criminals, then, with a +view to cutting off their posterity, we must be careful to understand +whether we are dealing with a hereditary or an acquired criminality. +If there is a genuine hereditary criminal taint, society is right in +freeing itself of it. If it is acquired criminality, then it is not +transmissible, and the offspring, if placed in a good environment, are +likely to be good citizens. All of<span class="pagenum"><a name="Page_269" id="Page_269">[Pg 269]</a></span> which means that, until we are +clearly sure of what constitutes a hereditary criminal trait, we +should move very slowly in the matter of mutilating criminals.</p> + +<p>What steps may the eugenist, with his present limited knowledge, +clearly, hopefully and confidently take to improve the future of the +human species? There is one avenue open to us in this matter in which +we can hardly go wrong. Even our mistakes can work little harm, and +every well-done piece of work in this field will be a blessing to the +race. This step lies in inculcating in our boys and girls high ideals +of parenthood. This is more effective than legal prohibition of +certain forms of marriage which cannot prevent matings, and adds the +curse of illegitimacy to the other handicaps of the children of such +unions. The first step in this process has already been reasonably +well accomplished. Both our boys and our girls are in love with +health. A good husband and a good wife should be healthy and vigorous. +This does not mean that we expect a boy or girl who is looking forward +to marriage to sit down and ask himself deliberately about the health +of the person with whom he would mate. We must fill our children with +the love of outdoor life, with the love of exercise. This will foster +in them an admiration for people who are vigorous of body and alert of +mind.<span class="pagenum"><a name="Page_270" id="Page_270">[Pg 270]</a></span> It ought to become practically impossible for a hearty and +vigorous boy to fall in love with a helpless and anæmic girl. It +should be equally impossible for a hale and active girl to admire a +man who was her inferior in either vigor or alertness. The modern +taste for outdoor life has largely brought this to pass among such of +our people as have leisure enough to indulge in vigorous sport. Among +the crowded dwellers in the closer sections of the city such life has +been so nearly impossible that no ideal of vigorous manhood or of +radiant womanhood has had a chance to grow up. With the oncoming of +the parks and play-grounds, all of this, we may hope, will change. +Health and vigor will be no less attainable and hence no less adorable +in the city than in the country. Rich and poor alike will be attracted +by rosy cheeks and an elastic gait.</p> + +<p>Our aim, however, should not cease with a vigorous body. We must teach +our young men and young women the glory of a well disciplined mind. +This should seem quite as admirable to them as a vigorous body. To +them, straight thought ought to be as lovable as a firm and supple +body. In this matter our young people are less exacting. The ordinary +conversation of people gathered together for social purposes is not +particularly intellectual, and any attempt to make it so at present +seems priggish. With a<span class="pagenum"><a name="Page_271" id="Page_271">[Pg 271]</a></span> broader education, will come keener demand for +intelligence. We may hope the time is not too far distant when a +question of governmental policy, a new book or play, or a new +discovery in science will stimulate as much conversational zest as now +seems to be gotten from a pack of cards.</p> + +<p>A third feature of the ideals which should be instilled into the minds +of our children is the moral phase. There seems little doubt that this +is on the way. We must not mistake an evident laxness of religious +observance as being synonomous with moral looseness. The revelations +which our recent periodicals have brought us concerning the habits of +business men, of politicians, and of society, have left on many minds +the impression that this is distinctly an age of decadence. Exactly +the reverse is the truth. This is the age of intense sensitiveness to +wrong. In almost no particular is it worse than any previous age in +the history of our country. We openly discuss things which we left +untouched a little while ago. We insistently demand that business +practices to which nobody particularly objected a dozen years ago must +now certainly cease. All of this has produced an erroneous impression +that the times are out of joint. But the dust and dirt in the air is +the unavoidable accompaniment of house cleaning. When doubtful +practices simply have publicity<span class="pagenum"><a name="Page_272" id="Page_272">[Pg 272]</a></span> many are awakened to the sense of +their duty to society. Persons who, of themselves, might be willing to +live low and godless lives, dare not do so in the face of society when +our social ideals are finer. I believe there is the utmost hope that +within two generations our young men and young women will scorn +meannesses which we are accepting with entire complacency.</p> + +<p>A close acquaintance with thousands of young men and young women +running through an experience of twenty-five years has taught me to +believe that our young people of to-day are altogether cleaner of +mind, of tongue, and of life than were their parents. There is freer, +franker discussion of many things that their parents would scarcely +have dared mention, yet I feel sure the moral tone is distinctly +higher. I look with entire hopefulness to an early season when the +young man who asks a woman to share her life with him will be met with +the entirely proper question, "Have you kept your life clean for this +event?" I believe that unless the answer can be in the affirmative the +young woman will not be able to have admiration enough for the young +man to cover uncleanness in his life.</p> + +<p>There is one temporary phase of present life which seems discouraging. +The increase in the cost of living, and still more rapid increase in +the standard of<span class="pagenum"><a name="Page_273" id="Page_273">[Pg 273]</a></span> living is shifting too late in life the age at which +our young people marry. The result is that one of two things is likely +to happen; either a large number of people are likely not to marry at +all, or the romantic time of life is passed before the event occurs +which it is intended to bless. A young man and young woman who are in +this time of life can deny themselves for each other, can struggle and +plan together, can hope and trust together to an extent that can never +be the case if marriage is delayed beyond the romantic years.</p> + +<p>The best foundation possible for a life of happiness is vigor, ability +and good character. For the lack of none of these can wealth properly +atone.</p> + +<p>There is an apparent tendency to waken to the situation. I hope it +will come soon enough for our young men and young women to get past a +desire for such establishments in life as their parents already have. +With this difficulty removed, with our widespread education, with the +constant diffusion of both information and ideals from our periodical +press I have every hope that the evolution of a new, a finer, and more +vigorous race, will come with a rapidity which nothing that the past +has done would lead us to expect.</p> + + + +<div class="section_break"></div> +<p><span class="pagenum"><a name="Page_274" id="Page_274">[Pg 274]</a></span></p> +<h3>CHAPTER XI</h3> + +<p class="chapter_subhead">Science and the Book</p> + + +<p>We of the twentieth century have an overwhelming desire to be up to +the times. Nothing but the latest news on any subject will completely +satisfy. We are more anxious for late information than for accurate +information. We have an almost unconquerable feeling that if it is +late it must be accurate. All of us are sensitive to being thought +behind the times. We feel that no stigma can be more invidious in the +intellectual world than the stigma of being out of date. This pervades +the masses quite as strongly as it does the more cultured classes. +Under these conditions everybody wants to know the latest theory that +science has to offer concerning anything that can be brought within +the range of their interests. As a result everybody would like to know +about evolution, were it not for the fact that a great mass of people +have been brought to believe that there is something inherently +irreligious in the idea. Our people have a saving sense of the value +of religion. Denominational control may set lightly upon them.<span class="pagenum"><a name="Page_275" id="Page_275">[Pg 275]</a></span> +Certain long revered doctrines may have little practical influence +upon them. Yet inherently they all believe in religion, and most of +them believe themselves to be religious, as indeed they really are.</p> + +<p>It is a most wholesome tendency which leads us to esteem religion as +the main interest in life. We must feel a sense of shame when we +consciously permit the influences, which most favorably mold our +character, to weaken their hold upon our lives. Certainly in our time +religion is the essential agent by which character is molded. Any of +us would be foolishly short-sighted were he willing to weaken the hold +of religion upon his life for the sake of a scientific theory, the +truth or falsity of which could have but little practical bearing upon +his conduct. We must hold to religion at all hazards. We may, when +circumstances so suggest, change our denominational allegiance. We may +and often do interpret our faith quite at variance with the +ecclesiastical body with which we are connected. We may constantly +modify and develop our beliefs. But it is a pitiful life which has +lost the staying and strengthening influence of religion. I believe +this conviction is deep-rooted in the minds of our people and that it +deserves the place it holds.</p> + +<p>To a mind thus essentially religious the announcements of science +often come as a shock. They seem<span class="pagenum"><a name="Page_276" id="Page_276">[Pg 276]</a></span> to run counter to our deepest +convictions. It seems impossible to us that both can be true. +Sometimes the more we debate the questions the more contradictory they +seem to become. Every good mind needs unity in itself. No clear +thinker can be quite content when two distinct departments of thought +are at sharp variance in his mind. He may pursue one of two courses. +He may hold to one view with conviction and earnestness and look upon +the other as essentially false. To many religious people all science +that runs counter to their convictions is necessarily false. They +label it pseudo-science and pass it by. If the word pseudo-science is +unknown to them, they stigmatize it as rationalistic, or still worse +as materialistic and let it go at that.</p> + +<p>The other course is to have faith both in religion and in science.</p> + +<p>Such a fair-minded man must ask himself, what is the truth in the +matter? If the scientific fact is true it is to be believed. It may +run counter to what we have believed before. It may seem at first +entirely incredible. But when once he becomes convinced of its truth +the clear thinker must not only accept it, but must accept all +legitimate deductions from it. If it seems true to us we must believe +it. Absolute demonstrable truth, except in the simplest of matters is +almost unattainable. The best we can ordinarily<span class="pagenum"><a name="Page_277" id="Page_277">[Pg 277]</a></span> get is a close +approach to certainty, and with this we must be content. In many +matters, indeed in most matters, we must trust the judgment of others +who are better trained in a particular line of thought.</p> + +<p>As to the truth of geology we are certainly wise to accept for the +present the facts and principles commonly accepted by competent +geologists. In biology, we should respect the concurrent opinion of +important biologists. We must not assume that a few biologists who +think as we do are right against the biological world, or that a few +geologists who think as we do are right against the geological world. +For theology, we had better go to the educated theologian. But when it +comes to reconciling two of these and to catching the inherent +correspondence between them, it is often likely that each of these +groups of men is unable to see clearly the view-point of the other. +Here lies our freedom. Here we must either think for ourselves or +think with those wiser than ourselves whose opinions seem to us to +ring true and to focus for us our wavering and uncertain thought.</p> + +<p>Among students of animals and plants there is no longer any question +as to the truth of evolution. That the animals of the present are the +altered animals of the past, that the plants of to-day are the<span class="pagenum"><a name="Page_278" id="Page_278">[Pg 278]</a></span> +modified plants of yesterday, that civilized man of to-day is the +savage of yesterday and the tree-dweller of the day before, is no +longer debatable to the great mass of biologists. To older men +hampered by the convictions of an earlier age this dictum of modern +science may still be a little uncertain.</p> + +<p>The working biologists of the world have no doubt. They differ +radically as to what brought about this change, they dispute +vigorously as to the rate of change, but as to the fact of the change +there is no difference of opinion. Under these conditions the thinking +man is out of joint with the times when he sets himself against the +idea of evolution. He may be so immersed in other lines as to be +indifferent to the problem; but when he is hostile to it, he marks +himself as clearly against his day. Many have been against their day +and have been right. Very great men have often been against the +opinions of their times and have come to be leaders of the world's +later thought. But ordinary men in ordinary times who think +differently on a special subject from the specialists of the times are +not very likely to be right. It is safe for most of us to accept as +true an opinion on which specialists on that subject agree. It seems +clear to me then that the thinking man to-day has in the matter of +evolution a double duty. He must become reasonably acquainted with the +theory that<span class="pagenum"><a name="Page_279" id="Page_279">[Pg 279]</a></span> so largely affects all present knowledge, and he must +wrestle with the theory until it no longer hinders the hold of +religion upon his life. He may be perfectly sure that he does not +clearly understand both, but he must get them into reasonable +concordance before he can be quite at peace.</p> + +<p>Truth is true no matter how it is acquired. There can be no doubt as +to the essential truth of religion: its fruits proclaim its worth. +There can be no doubt as to the essential truth of evolution; the +clarity it has brought into the sciences is the evidence of the value +of the conception. That it will persist in its present form, that it +will be unchanged by later additions to our knowledge is of course +unthinkable. It may be incomplete, it may be undeveloped, but so far +as it goes it contains the truth. Under these conditions, how can we +bring peace into our own mind? These two important provinces seem so +often to be at variance. The difficulty may lie in one of two places. +In the first place, each truth may be stated in terms so peculiar to +its own subject as to convey no meaning to the student of the other +branch. There is a second, and more harassing possibility. The same +words may be used by students in each branch but each side may put a +different significance into the terms. Then each believes he +understands the other, when he really does not.</p> + +<p><span class="pagenum"><a name="Page_280" id="Page_280">[Pg 280]</a></span>Our theology is man's interpretation of God's revelations of Himself +as recorded in the Bible. Our science is man's interpretation of God's +revelation of Himself in nature. Each is God's revelation, and so far +as we have understood it, that revelation is of the utmost importance +in our lives. Each has all the inherent short-comings of man's +interpretation. Each has all the difficulties necessarily found in any +stage of a developing understanding. We may be sure if we could +thoroughly understand God's revelation of Himself as recorded in the +Bible and his revelation of Himself as recorded in the rocks and the +tissues of animals as well as in the body and mind of man to-day, +there would be no difficulty. When we understand both completely, as +perhaps we never shall, there will be no contradictions of any kind +between them. Even now if we are firmly convinced that truth must be +in both, there will be little difficulty in reaching a workable unity +which will satisfy the present needs of the human mind and will not be +so crystallized as to prevent a future growth. If, however, we hope to +find a unity between a belief in evolution and a belief in the +inspiration and value of the Bible, we must accept both of these in +the terms of to-day. To reconcile a twentieth century statement of +science with an eighteenth century statement of theology would be as<span class="pagenum"><a name="Page_281" id="Page_281">[Pg 281]</a></span> +absurd as it would be to reconcile a statement of twentieth century +theology with eighteenth century science. Each century must restate +its truths in terms of its own time. The truths may be at bottom the +same through many centuries but to be clearly intelligible in any +century they must be couched in the terminology of the age.</p> + +<p>It seems to me if we are to understand, in conformity with the thought +of the age, any particular book in the Bible, there are three steps +through which we must pass. We must first ask ourselves the kind of +people to whom the book was originally written. We must know their +habits of life and of thought. Until this is clear in our minds the +book can have little significance. Having built up as nearly as may be +the life and thought of the time, we must next decide what is the +inherent truth taught to the people of that time by the book under +consideration. Much that is written must be simply the setting in +which alone that truth could reach them. This extraneous detail gives +vigor and color to the message but is not the message itself. The last +step and the hardest one to take, the one that to some minds seems +almost irreverent, is to decide the form that message must take to-day +to convey to our minds the same truth which the original message +conveyed to the people of its time. In so far as we succeed in taking +these<span class="pagenum"><a name="Page_282" id="Page_282">[Pg 282]</a></span> three steps, we shall get the true message which this book +holds for us to-day.</p> + +<p>When Paul in his first burning letter told the Corinthian congregation +that their women should be silent in their churches, he is not, it +seems to me, giving a message which in those terms applies to the +world to-day. If a woman has anything that is worth saying she has a +perfect right to say it in church. In any denomination in which +religious observance is not ecclesiastically formal she will be +allowed that privilege. By an interesting peculiarity of mind on our +part she may be permitted to do so upon Wednesday evenings, when our +early prejudice still prevents her speaking on Sunday. What is the +truth of the teaching of Paul in this matter? The Christians of +Corinthian times had already begun to suffer from persecution. They +were already despised and distrusted. Men had come to speak ill of +them. Paul's injunction concerning the silence of women in churches +was simply an injunction against their doing those things which in the +thought and habit of those times were associated generally with +looseness of character. Fine Corinthian women did not speak in public. +A woman who would consent to speak before a group of men of Corinth of +that day would by that fact have proclaimed herself a woman of loose +morals. Paul's injunction is that, in this desperate strug<span class="pagenum"><a name="Page_283" id="Page_283">[Pg 283]</a></span>gle +Christian women should do nothing which could possibly bring them into +disrepute. The lives of Christians must be above suspicion. This +message is certainly as true to-day as it was in the time of Paul and +Corinth. Whether or not a woman speaks in church to-day has no bearing +whatever upon the question. The question is how she speaks and what +she says. If her life gives force to her message and her message +contains God's truth she is entirely free to speak.</p> + +<p>In similar fashion we have changed most beautifully the message which +we have come to love, as the Mizpah message: "The Lord watch between +thee and me while we are absent one from the other." We have +absolutely transformed and glorified the message. It was once the +calling down of the wrath of Jehovah upon one or other of two herdsmen +if either of them should fail to comply with the agreement to remain +within his own boundary. These men whose herdsmen were constantly +stealing each other's cattle agreed to separate because they could not +live in unity. They set up a heap of unhewn stone, and called upon God +to guard and to see that neither of them passed beyond the boundary of +the other. What was once a threat between warring herdsmen has become +a binding link between Christian brothers. No longer do we call upon +the Lord<span class="pagenum"><a name="Page_284" id="Page_284">[Pg 284]</a></span> to guard in our absence lest our enemy encroach upon our +domain. Now we call upon him to bind our hearts together so that +neither time nor circumstance can bring division between us. The +menace of a herdsman's wrath has become one of the tenderest messages +of Christian love.</p> + +<p>In the light of the principles stated above, what is the essential +truth that lies back of the earliest chapters of Genesis? First, that +there is one God. Slowly it had been borne in upon the Hebrew mind as +upon no other tribe in the world that the Lord God is one God. Nearly +all the world besides believed in many gods. Each nation had a God +peculiarly its own, each city had a minor god caring for it +particularly. There were gods of the woods, gods of the oceans, gods +of the streams. Gods and goddesses were everywhere. To this people +wandering through the terrible monotony of the sandy desert, the +"Garden of Allah," there came the inspired comprehension of the +eternal oneness of Almighty God. First, he was to most of them the God +of the Hebrew, stronger than the gods of the nations. After a while +under the teaching of prophet after prophet there finally came to the +entire nation the exalted conception that God is one and there is no +other God. This is one of the imperishable revelations of all time. +Beside this, all suggestions of fifth or sixth day, of hours or of +ages<span class="pagenum"><a name="Page_285" id="Page_285">[Pg 285]</a></span> are absolutely insignificant. These are but the clothing of the +idea which makes it acceptable to its time. This clothing must change +with every age if it would reach thoroughly the minds of the age. +Underneath and forever lies the glorious truth that the Lord God is +one God.</p> + +<p>The second truth which seems to me to underlie this magnificent +parable of creation is the truth that this great God has created the +universe and that he cares for his people. Gods before had been +objects of terror. Gods before had lived lives such as the people +themselves would not have respected among their companions. Gods +before were to be shunned. If one could but escape the attention of +the gods it was his greatest good fortune. Now we have the conception +of an all-knowing, ever-present God to whom his people are dear. The +terms in which it was stated in those days matter but little. To +modern psychologists even the idea that people are dear to God seems +speaking too humanly. Yet the truth involved must come in terms that +the people of to-day understand. We can best comprehend God if we +think of Him as loving and chastening, even though down in our hearts +we know that these terms are not high enough, are too human to apply +to an Eternal God. But we know no better and they tell us the truth +even though the terms may in time pass completely away.</p> + +<p><span class="pagenum"><a name="Page_286" id="Page_286">[Pg 286]</a></span>Last of all and perhaps most characteristic of the Hebrew people is +the great lesson that this Eternal God, who created the universe and +cares for his people, demands righteousness of his people. To the +nations round about religion was not a matter of righteousness. For +them religion had nothing to do with morality. Thieves might have gods +favorable to them quite as well as righteous men. The worship of Diana +of the Ephesians or of Astarte in the groves of the Asia Minor coast +could be so unspeakably licentious and vile as not to admit of +description to-day. Yet this was all religion. To the Hebrew came the +inspired, exalted conception of a God who demanded righteousness of +his people. Beside this wonderful revelation to the human mind details +of serpents, and of apples, of names of men and of women, of gardens +and of swords are absolutely but the transitory clothing. This brought +them to the minds of the times. The value of the form is evidenced by +the fact that it brought the conception. But we must not lose the +glory of the conception in an over regard for the clothing in which +the idea came.</p> + +<p>Does this mean that Genesis has served its purpose and is to-day to be +conceived of as a beautiful relic of the past, to be reverently +enshrined but not seriously accepted? Far from it. The glory of the +Genesis story lies in its wonderful power to grow. It strength<span class="pagenum"><a name="Page_287" id="Page_287">[Pg 287]</a></span>ened +the minds of a persecuted tribe wandering in the desert who finally +settled in a small and barren country. It brought the truth to them so +clearly that they have persuaded much of the world of that truth and +bid fair to persuade the rest. The story has grown with the mind of +man. As it served the Hebrew in his time it has grown to serve others +to this day. Each generation has read the story in the light of its +own times and each generation will continue to read the story in the +light of its advancing knowledge. The only part of the story that can +be affected is the clothing, the inherent truth remains forever. +Furthermore, the story which persuaded the childhood of race is the +story which will persuade the childhood of to-day. In no other form +could the great truth of the Bible be brought to our children as well +as in the form of these early chapters. In early life our children +will accept these stories as literally as the ancient Hebrew accepted +them. As they grow in knowledge, unconsciously and without jar, if we +do not jar them, our children will read into the story what God has +taught them in the world outside. The shock which came to their elders +need never come to them. It is our fault if our children are disturbed +by the conflict between religion and science which disturbed us. There +is no difference between God's revelation of Himself, as we have it in +the Bible, and<span class="pagenum"><a name="Page_288" id="Page_288">[Pg 288]</a></span> God's revelation of Himself in nature. The better we +know the Bible and the better we know nature the clearer this will be +to us.</p> + +<p>Perhaps the most severe shock that has come to the mind of religious +man from the teachings of science has been the at first almost +unsupportable idea that man is the descendant of creatures of which +the ape is to-day the nearest representative. He had learned from +Genesis the altogether adorable conception that he was made in the +image of his Maker. It lifted him; it strengthened him; it gave him +more power to struggle. He might know that he had marred that likeness +by wrong-doing, he might understand that the fullness of the glory of +God's image could not shine through his own face. Yet he believed that +he was, in spite of all his imperfections, made in the image of his +Maker. Now comes this horrible linkage with a miserable brute to +either shock and confound him or to degrade him. We can easily +imagine, some of us have bitterly experienced, the shock of this +changed conception. But it was only because we mistook the clothing +for the truth in both cases. We read science in its own terms; we read +Genesis in its own terms. They did not use the same language and they +jarred us to the very soul. Slowly, however, we are coming out of the +darkness of that battle; slowly the glorious light of the beauti<span class="pagenum"><a name="Page_289" id="Page_289">[Pg 289]</a></span>ful +truth is breaking into our minds and our hearts.</p> + +<p>Michael Angelo painted a wonderful picture of "The Judgment." Here, +seated upon a throne, which after all is only a magnificent chair, +sits a venerable figure of what is really but a nobly-proportioned +man, to whom the nations come for their final reward. He separates the +righteous from those who must forever be sundered from their God. Seen +through the distant past it still remains a majestic picture; but no +painter would think of repeating its conception to-day.</p> + +<p>Quite in the modern spirit is the beautiful lunette which John Sargent +placed in the Boston Library, above his well known frieze of "The +Prophets." It represents "Jehovah confounding the gods of the +nations." The naked figure of suppliant Israel stands before an altar +of unhewn stones, on which burns the sacrifice. The smoke ascends to +Heaven. On one side stands the mighty figure of Assyria with uplifted +mace ready to strike its awful blow upon the shoulders of helpless +Israel. On the other side the lithe, subtle form of Egypt, clasping +the knout, watches its chance to bring its treacherous thong upon the +helpless shoulders of suffering Israel. But Jehovah may not appear, +man may not look on God and live. Jehovah is seen as a glory behind +the cloud of smoke shrouded by winged cherubim. From one<span class="pagenum"><a name="Page_290" id="Page_290">[Pg 290]</a></span> side of the +cloud comes a mighty hand meeting with power the force of Assyria. +From the other side, a lithe and sinewy hand thwarts the subtlety of +Egypt. But Jehovah is behind the cloud.</p> + +<p>Again we understand that we are made in the image of our Maker. Again +we understand the power of the uplift of this idea. From the conflict +it has emerged in new and glorified form. Hath a God eyes that he may +see? Hath a God ears that he may hear? Hath a God hands that he may +work? These we know to be but human forms of speaking. Eyes, ears, and +hands we may owe to the brute from whom we have sprung; in our eyes +and ears and hands we show the relationship we bear to them. These are +not the image of God. God is a deeper, a finer, a nobler something +than hands, than ears and eyes. The image of God lies within +ourselves: the image of God is that which makes us what we are. In +every noble purpose, in every earnest endeavor to uplift ourselves or +our fellowman, in every thought that turns us from the evil of a +repented past, in every desire with which our hearts yearn to +strengthen, support and sustain our friends and even our enemies, +shines forth the image of Almighty God. This it is that links us with +the Eternal: this it is that makes it worth while that we should be +Eternal. Besides this what are hands and ears and eyes? We<span class="pagenum"><a name="Page_291" id="Page_291">[Pg 291]</a></span> are made, +all in us that is noblest and highest, in the image of our Maker.</p> + +<p>A word in closing. The time is ripe for a broader conception of +theology and of science on the part of those who are not trained to be +specialists in either. We are becoming more and more inherently +religious. We are becoming more and more enamored of the truth in all +its forms. The times are ripe for us to cease the struggle and to +strive for peace. So long as men insist that the important things in +faith are the things on which men differ there will be eternal strife. +So soon as men endeavor to find the common ground between them and +each tries to state his belief in forms acceptable to himself but +involving no hostility to his neighbor, we shall be working for peace.</p> + +<p>Some of our finest men of to-day are being trained in modern science +and in modern theology. There is no scorn in their minds for early +science or for early theology. Each served its age, and each taught +its truth. But its truth must be restated in terms of to-day. The old +creeds will always be loved. The old creeds will always hold our +reverence and allegiance. But each age must be at liberty to interpret +these creeds in the terms in which that age best understands truth. +Each age must be at liberty "to restate the doctrines of the past in +accordance<span class="pagenum"><a name="Page_292" id="Page_292">[Pg 292]</a></span> with the newness of the age and with the ancient verity of +truth." How feeble my own attempt is in this matter, I quite +understand; I am still a child of the struggle. It has all come in my +lifetime and I have seen and felt not a little of the bitterness of +it. I believe the time is ripe for a definite peace. I believe our +children, if we do not hamper them, will never know the struggle we +have had. In every great institution throughout this broad land men of +earnest mind and noble soul are teaching the truth as God gives it to +them to know the truth. Let us not hesitate to entrust our children to +their hands. To us they may seem to be teachers of discord but they +are not speaking in terms that we understand. They are using the +language of a new age. Underneath their teaching lies the everlasting +truth. Out of their teaching will come everlasting life. Let us trust +God in the world. Let us believe that in this age he is teaching men's +lips and dwelling in men's hearts. Only so can we give to our children +the best their times can give them. If we insist in holding these men +back to our conception we but deny them the privilege of moving with +God's great procession. We make them laggards when they should be in +the front ranks, their faces lighted by a nearer and clearer vision of +Almighty truth.</p> + + + +<div class="section_break"></div> +<p><span class="pagenum"><a name="Page_293" id="Page_293">[Pg 293]</a></span></p> +<h2>INDEX</h2> + +<div id="index"> +<h3>A</h3> + +<p>Acquired characters not inherited, <a href="#Page_52">52</a>.</p> + +<p>Adaptation and purpose, <a href="#Page_89">89</a>.</p> + +<p>Adaptation for the individual, <a href="#Page_87">87</a>.</p> + +<p>Adaptation for the species, <a href="#Page_125">125</a>.</p> + +<p>Advanced teaching, <a href="#Page_291">291</a>.</p> + +<p>Agassiz and evolution, <a href="#Page_19">19</a>.</p> + +<p>Age of the earth, <a href="#Page_156">156</a>.</p> + +<p>Allantois of chick, <a href="#Page_206">206</a>.</p> + +<p>American Museum of Natural History, <a href="#Page_221">221</a>.</p> + +<p>Anaxagoras and evolution, <a href="#Page_9">9</a>.</p> + +<p>Anaximander and evolution, <a href="#Page_8">8</a>.</p> + +<p>Ancestry of man, <a href="#Page_186">186</a>.</p> + +<p>Andes rising out of Pacific, <a href="#Page_32">32</a>.</p> + +<p>Aquinas, Thomas, and evolution, <a href="#Page_12">12</a>.</p> + +<p>Archæopteryx, <a href="#Page_181">181</a>.</p> + +<p>Aristotle and evolution, <a href="#Page_9">9</a>.</p> + +<p>Armadillo and glyptodon, <a href="#Page_29">29</a>.</p> + +<p>Artificial flavors, <a href="#Page_161">161</a>.</p> + +<p>Artificial proteids, <a href="#Page_161">161</a>.</p> + +<p>Artificial sugars, <a href="#Page_161">161</a>.</p> + +<p>Ascent of man, <a href="#Page_189">189</a>.</p> + +<p>Asexual reproduction, <a href="#Page_194">194</a>.</p> + +<p>Augustine, Saint, and evolution, <a href="#Page_11">11</a>.</p> + +<p>Australian mammals, <a href="#Page_186">186</a>.</p> + + +<h3>B</h3> + +<p>Bank swallow's nest, <a href="#Page_146">146</a>.</p> + +<p>Barnacles studies by Darwin, <a href="#Page_34">34</a>.</p> + +<p>Beagle and Darwin's voyage, <a href="#Page_25">25</a>.</p> + +<p>Beauty of human female, <a href="#Page_127">127</a>.</p> + +<p>Biologists accept evolution, <a href="#Page_278">278</a>.</p> + +<p>Bird colors, <a href="#Page_131">131</a>.</p> + +<p>Bird from reptile, <a href="#Page_122">122</a>.</p> + +<p>Bird nests, <a href="#Page_145">145</a>.</p> + +<p>Birds of a region definite, <a href="#Page_61">61</a>.</p> + +<p>Bird song, <a href="#Page_135">135</a>.</p> + +<p>Blowing viper, <a href="#Page_107">107</a>.</p> + +<p>Blue birds and frost, <a href="#Page_61">61</a>.</p> + +<p>Bradbury, Dean, <a href="#Page_43">43</a>.</p> + +<p>Buffon and evolution, <a href="#Page_15">15</a>.</p> + +<p>Bumble bees, <a href="#Page_125">125</a>.</p> + +<p>Butterfly colors, <a href="#Page_129">129</a>.</p> + +<p>Butterfly's mouth, <a href="#Page_95">95</a>.</p> + + +<h3>C</h3> + +<p>Carboniferous age, <a href="#Page_174">174</a>.</p> + +<p>Carnivorous teeth, <a href="#Page_124">124</a>.</p> + +<p>Caterpillars on leaves, <a href="#Page_110">110</a>.</p> + +<p>Cave man, <a href="#Page_188">188</a>.</p> + +<p>Cells live in water, <a href="#Page_166">166</a>.</p> + +<p>Cenozoic age, <a href="#Page_185">185</a>.</p> + +<p>Cicada killer, <a href="#Page_143">143</a>.</p> + +<p>Circular nest of bird, <a href="#Page_147">147</a>.</p> + +<p>City life in man, <a href="#Page_256">256</a>.</p> + +<p>Clothing of birds, <a href="#Page_101">101</a>.</p> + +<p>Coal plants, <a href="#Page_174">174</a>.</p> + +<p>Cold-blooded animals, <a href="#Page_99">99</a>.</p> + +<p>Color, concealing, Thayer, <a href="#Page_115">115</a>.</p> + +<p>Concealing appearance, <a href="#Page_105">105</a>.</p> + +<p><span class="pagenum"><a name="Page_294" id="Page_294">[Pg 294]</a></span>Cope and Lamarckianism, <a href="#Page_244">244</a>.</p> + +<p>Cope on taste of toad, <a href="#Page_118">118</a>.</p> + +<p>Coral reef formation, <a href="#Page_32">32</a>.</p> + +<p>Country life in man, <a href="#Page_256">256</a>.</p> + +<p>Cretaceous period, <a href="#Page_180">180</a>.</p> + +<p>Cricket song, <a href="#Page_134">134</a>.</p> + +<p>Crinoids, <a href="#Page_171">171</a>.</p> + +<p>Crossing and variation, <a href="#Page_53">53</a>.</p> + +<p>Cuvier criticises Lamarck, <a href="#Page_19">19</a>.</p> + + +<h3>D</h3> + +<p>Darwin, Charles,<br /> + <span class="indent1">along La Plata, <a href="#Page_28">28</a>.</span><br /> + <span class="indent1">at Buenos Ayres, <a href="#Page_28">28</a>.</span><br /> + <span class="indent1">at Keeling Atoll, <a href="#Page_31">31</a>.</span><br /> + <span class="indent1">at Galapagos, <a href="#Page_30">30</a>.</span><br /> + <span class="indent1">father of evolution, <a href="#Page_21">21</a>.</span><br /> + <span class="indent1">in Brazil, <a href="#Page_27">27</a>.</span><br /> + <span class="indent1">in Patagonia, <a href="#Page_29">29</a>.</span><br /> + <span class="indent1">in Peru, <a href="#Page_30">30</a>.</span><br /> + <span class="indent1">on Beagle, <a href="#Page_26">26</a>.</span><br /> + <span class="indent1">persuaded world of evolution, <a href="#Page_21">21</a>.</span><br /> + <span class="indent1">studies Lyell's Geology, <a href="#Page_26">26</a>.</span><br /> + <span class="indent1">studies Malthus, <a href="#Page_35">35</a>.</span></p> + +<p>Darwin, Erasmus, and evolution, <a href="#Page_16">16</a>.</p> + +<p>Darwin's ancestry, <a href="#Page_22">22</a>.<br /> + <span class="indent1">birth, <a href="#Page_23">23</a>.</span><br /> + <span class="indent1">burial in Abbey, <a href="#Page_43">43</a>.</span><br /> + <span class="indent1">death, <a href="#Page_43">43</a>.</span><br /> + <span class="indent1">education, <a href="#Page_23">23</a>.</span><br /> + <span class="indent1">narrative of voyage, <a href="#Page_33">33</a>.</span><br /> + <span class="indent1">patient mind, <a href="#Page_45">45</a>.</span><br /> + <span class="indent1">purity of mind, <a href="#Page_29">29</a>.</span><br /> + <span class="indent1">return to England, <a href="#Page_33">33</a>.</span><br /> + <span class="indent1">short sketches, <a href="#Page_39">39</a>.</span><br /> + <span class="indent1">study of barnacles, <a href="#Page_34">34</a>.</span><br /> + <span class="indent1">work double, <a href="#Page_233">233</a>.</span></p> + +<p>Deer horns, <a href="#Page_138">138</a>.</p> + +<p>Descartes and evolution, <a href="#Page_12">12</a>.</p> + +<p>Descent of man, <a href="#Page_189">189</a>.</p> + +<p>Determinants in nucleus, <a href="#Page_238">238</a>.</p> + +<p>Development of chick, <a href="#Page_204">204</a>.</p> + +<p>Development of pond-snails, <a href="#Page_46">46</a>.</p> + +<p>Devonian age, <a href="#Page_173">173</a>.</p> + +<p>Devonian fish, <a href="#Page_173">173</a>.</p> + +<p>DeVries and mutation, <a href="#Page_246">246</a>.</p> + +<p>Duckmole, <a href="#Page_208">208</a>.</p> + + +<h3>E</h3> + +<p>Early marriage, <a href="#Page_272">272</a>.</p> + +<p>Earth's age, <a href="#Page_155">155</a>.</p> + +<p>Ecstatic flight, <a href="#Page_136">136</a>.</p> + +<p>Egg-laying mammals, <a href="#Page_208">208</a>.</p> + +<p>Eimer and orthogenesis, <a href="#Page_243">243</a>.</p> + +<p>Elements of Geology, Lyell, <a href="#Page_26">26</a>.</p> + +<p>Emanuel Kant and evolution, <a href="#Page_13">13</a>.</p> + +<p>Embryo of chick, <a href="#Page_203">203</a>.</p> + +<p>Emerson and nature, <a href="#Page_48">48</a>.</p> + +<p>Empedocles and evolution, <a href="#Page_8">8</a>.</p> + +<p>English sparrow (see <a href="#sparrow_english">Sparrow, English</a>).</p> + +<p>Environment in man, <a href="#Page_258">258</a>.</p> + +<p>Eugenic program, <a href="#Page_269">269</a>.</p> + +<p>Evening primrose and mutation, <a href="#Page_246">246</a>.</p> + +<p>Evolution since Darwin, <a href="#Page_233">233</a>.</p> + + +<h3>F</h3> + +<p>Feeble-mindedness, <a href="#Page_264">264</a>.</p> + +<p>Feet of mammals, <a href="#Page_122">122</a>.</p> + +<p>First living things, <a href="#Page_165">165</a>.</p> + +<p>Fish eggs, <a href="#Page_145">145</a>.</p> + +<p>Fish may freeze, <a href="#Page_104">104</a>.</p> + +<p>Fitz-Roy, Capt., and Beagle, <a href="#Page_25">25</a>.</p> + +<p>Freedom of teaching, <a href="#Page_291">291</a>.</p> + +<p><span class="pagenum"><a name="Page_295" id="Page_295">[Pg 295]</a></span>Fright paralysis, <a href="#Page_108">108</a>.</p> + +<p>Frog's long tadpole stage, <a href="#Page_112">112</a>.</p> + +<p>Frost and bluebirds, <a href="#Page_61">61</a>.</p> + +<p>Fur of seal, <a href="#Page_100">100</a>.</p> + +<p>Future evolution of man, <a href="#Page_249">249</a>.</p> + + +<h3>G</h3> + +<p>Galapagos Islands and evolution, <a href="#Page_30">30</a>.</p> + +<p>Geological periods, <a href="#Page_158">158</a>.</p> + +<p>Glyptodon and armadillo, <a href="#Page_29">29</a>.</p> + +<p>Goethe and evolution, <a href="#Page_20">20</a>.</p> + +<p>Graphite from plants, <a href="#Page_168">168</a>.</p> + +<p>Grasshopper's mouth, <a href="#Page_93">93</a>.</p> + +<p>Grasshopper song, <a href="#Page_133">133</a>.</p> + +<p>Groundhog and winter, <a href="#Page_103">103</a>.</p> + +<p>Growth of North America, <a href="#Page_167">167</a>.</p> + + +<h3>H</h3> + +<p>Haeckel advocates evolution, <a href="#Page_42">42</a>.</p> + +<p>Health certificates, <a href="#Page_263">263</a>.</p> + +<p>Henslow and Darwin's education, <a href="#Page_24">24</a>.</p> + +<p>Henslow suggests Darwin for Beagle, <a href="#Page_24">24</a>.</p> + +<p>Heredity and natural selection, <a href="#Page_45">45</a>.</p> + +<p>Heredity in man, <a href="#Page_258">258</a>.</p> + +<p>Homes, few animals have, <a href="#Page_98">98</a>.</p> + +<p>Homes, warm-blooded animals, <a href="#Page_101">101</a>.</p> + +<p>Horn of rhinoceros, <a href="#Page_123">123</a>.</p> + +<p>Horns of deer, <a href="#Page_138">138</a>.</p> + +<p>Horse and early man, <a href="#Page_232">232</a>.<br /> + <span class="indent1">earliest, <a href="#Page_223">223</a>.</span><br /> + <span class="indent1">neck, <a href="#Page_229">229</a>.</span><br /> + <span class="indent1">story of, <a href="#Page_220">220</a>.</span><br /> + <span class="indent1">three-toed, <a href="#Page_227">227</a>.</span></p> + +<p>Horseshoe crab, <a href="#Page_171">171</a>.</p> + +<p>How mammals developed, <a href="#Page_192">192</a>.</p> + +<p>Huxley at Oxford meeting, <a href="#Page_42">42</a>.</p> + + +<h3>I</h3> + +<p>Ichneumon fly, <a href="#Page_142">142</a>.</p> + +<p>Image of God, <a href="#Page_288">288</a>.</p> + +<p>Improving the environment, <a href="#Page_259">259</a>.</p> + +<p>Improving the stock, <a href="#Page_261">261</a>.</p> + +<p>Inheritance of acquired characters, <a href="#Page_238">238</a>.</p> + +<p>Insect's biting mouth, <a href="#Page_93">93</a>.</p> + +<p>Interpretation of Genesis, <a href="#Page_284">284</a>.</p> + +<p>Isolation, Jordan, <a href="#Page_242">242</a>.</p> + +<p>Isolation, Romanes, <a href="#Page_242">242</a>.</p> + +<p>Isolation, Wagner, <a href="#Page_241">241</a>.</p> + + +<h3>J</h3> + +<p>Java skull, <a href="#Page_187">187</a>.</p> + +<p>Jehovah confounding the nations, <a href="#Page_289">289</a>.</p> + +<p>Jordan and isolation, <a href="#Page_242">242</a>.</p> + +<p>Judgment, Michael Angelo, <a href="#Page_289">289</a>.</p> + +<p>Jukes family, <a href="#Page_265">265</a>.</p> + +<p>June-bug, <a href="#Page_107">107</a>.</p> + + +<h3>K</h3> + +<p>Kallikak family, <a href="#Page_265">265</a>.</p> + +<p>Kant and evolution, <a href="#Page_13">13</a>.</p> + +<p>Katydid's color, <a href="#Page_111">111</a>.</p> + +<p>Katydid's song, <a href="#Page_133">133</a>.</p> + +<p>Keeling Atoll and Darwin, <a href="#Page_31">31</a>.</p> + +<p>King Crab, <a href="#Page_171">171</a>.</p> + + +<h3>L</h3> + +<p>Lamarck and evolution, <a href="#Page_17">17</a>.</p> + +<p>Lampshells, <a href="#Page_172">172</a>.</p> + +<p><span class="pagenum"><a name="Page_296" id="Page_296">[Pg 296]</a></span>La Place's theory, <a href="#Page_151">151</a>.</p> + +<p>Leibnitz, and evolution, <a href="#Page_13">13</a>.</p> + +<p>Life from other planets, <a href="#Page_162">162</a>.</p> + +<p>Life in the past, <a href="#Page_149">149</a>.</p> + +<p>Life, its nature, <a href="#Page_247">247</a>.</p> + +<p>Linnæan Society and evolution, <a href="#Page_40">40</a>.</p> + +<p>Linnæus and fixed species, <a href="#Page_15">15</a>.</p> + +<p>Locust's song, <a href="#Page_135">135</a>.</p> + +<p>Lucretius and evolution, <a href="#Page_10">10</a>.</p> + +<p>Lung-fish, <a href="#Page_176">176</a>.</p> + +<p>Lyell's Geology, <a href="#Page_26">26</a>.</p> + + +<h3>M</h3> + +<p>Male birds brighter, <a href="#Page_131">131</a>.</p> + +<p>Male insects sing, <a href="#Page_134">134</a>.</p> + +<p>Malthus and population, <a href="#Page_35">35</a>.</p> + +<p>Mamma, significance of, <a href="#Page_211">211</a>.</p> + +<p>Mammals, egg-laying, <a href="#Page_208">208</a>.<br /> + <span class="indent1">how developed, <a href="#Page_192">192</a>.</span></p> + +<p>Man and God's image, <a href="#Page_288">288</a>.<br /> + <span class="indent1">early, and horse, <a href="#Page_232">232</a>.</span><br /> + <span class="indent1">growing better, <a href="#Page_255">255</a>.</span></p> + +<p>Man's ancestry, <a href="#Page_250">250</a>.<br /> + <span class="indent1">future evolution, <a href="#Page_249">249</a>.</span></p> + +<p>Mating and song, <a href="#Page_133">133</a>.</p> + +<p>Mating antics, <a href="#Page_136">136</a>.</p> + +<p>Meaning of Genesis, <a href="#Page_284">284</a>.</p> + +<p>Megatherium and sloth, <a href="#Page_29">29</a>.</p> + +<p>Mesozoic age, <a href="#Page_178">178</a>.</p> + +<p>Michael Angelo, Judgment, <a href="#Page_289">289</a>.</p> + +<p>Migration of birds, <a href="#Page_103">103</a>.</p> + +<p>Missing link, <a href="#Page_187">187</a>.</p> + +<p>Mizpah, <a href="#Page_283">283</a>.</p> + +<p>Modern teachers of biology, <a href="#Page_291">291</a>.</p> + +<p>Mongolian idiot, <a href="#Page_265">265</a>.</p> + +<p>Mosquito's bite, <a href="#Page_97">97</a>.</p> + +<p>Mosquito's mouth, <a href="#Page_96">96</a>.</p> + +<p>Mother-love, <a href="#Page_217">217</a>.</p> + +<p>Multiplication and evolution, <a href="#Page_54">54</a>.</p> + +<p>Mutation and DeVries, <a href="#Page_246">246</a>.</p> + + +<h3>N</h3> + +<p>Nature of life, <a href="#Page_247">247</a>.</p> + +<p>Nature of milk, <a href="#Page_214">214</a>.</p> + +<p>Natural selection explained, <a href="#Page_45">45</a>.<br /> + <span class="indent1">in brief, <a href="#Page_36">36</a>.</span></p> + +<p>Nebular hypothesis, <a href="#Page_152">152</a>.</p> + +<p>Neck of horse, <a href="#Page_229">229</a>.</p> + +<p>Neo-Darwinians, <a href="#Page_237">237</a>.</p> + +<p>Nests for warm eggs, <a href="#Page_101">101</a>.</p> + +<p>Number and position of breasts, <a href="#Page_215">215</a>.</p> + + +<h3>O</h3> + +<p>Odor as protection, <a href="#Page_117">117</a>.</p> + +<p>Opossum playing dead, <a href="#Page_107">107</a>.</p> + +<p>Origin of birds, <a href="#Page_181">181</a>.<br /> + <span class="indent1">feathers, <a href="#Page_102">102</a>.</span><br /> + <span class="indent1">flight, <a href="#Page_122">122</a>.</span><br /> + <span class="indent1">hair, <a href="#Page_102">102</a>.</span><br /> + <span class="indent1">life, <a href="#Page_159">159</a>.</span><br /> + <span class="indent1">lungs, <a href="#Page_177">177</a>.</span><br /> + <span class="indent1">milk glands, <a href="#Page_212">212</a>.</span><br /> + <span class="indent1">placenta, <a href="#Page_210">210</a>.</span><br /> + <span class="indent1">variations, <a href="#Page_50">50</a>.</span></p> + +<p>"Origin of Species" published, <a href="#Page_41">41</a>.</p> + +<p>Orthogenesis and Eimer, <a href="#Page_243">243</a>.</p> + +<p>Oxford meeting of British Association, <a href="#Page_41">41</a>.</p> + + +<p><span class="pagenum"><a name="Page_297" id="Page_297">[Pg 297]</a></span></p> +<h3>P</h3> + +<p>Palæozoic era, <a href="#Page_170">170</a>.</p> + +<p>Paley's Natural Theology, <a href="#Page_87">87</a>.</p> + +<p>Pangenesis, <a href="#Page_236">236</a>.</p> + +<p>Patagonia and its terraces, <a href="#Page_29">29</a>.</p> + +<p>Phenacodus, <a href="#Page_185">185</a>.</p> + +<p>Physical evolution of man, <a href="#Page_254">254</a>.</p> + +<p>Pithecanthropus, <a href="#Page_188">188</a>.</p> + +<p>Planetesimal theory, <a href="#Page_155">155</a>.</p> + +<p>Playing dead, <a href="#Page_107">107</a>.</p> + +<p>Playing 'possum, <a href="#Page_107">107</a>.</p> + +<p>Polygamy in animals, <a href="#Page_137">137</a>.</p> + +<p>Pond-snail, development of, <a href="#Page_46">46</a>.</p> + +<p>Potato worm, <a href="#Page_142">142</a>.</p> + +<p>Protective coloration, <a href="#Page_109">109</a>.</p> + +<p>Protoplasm, <a href="#Page_164">164</a>.</p> + +<p>Pterodactyl, <a href="#Page_180">180</a>.</p> + +<p>Puff adder, <a href="#Page_107">107</a>.</p> + +<p>Purpose and adaptation, <a href="#Page_89">89</a>.</p> + +<p>Purpose in nature, <a href="#Page_88">88</a>.</p> + + +<h3>Q</h3> + +<p>Quiet and escape, <a href="#Page_105">105</a>.</p> + + +<h3>R</h3> + +<p>Raining toads, <a href="#Page_113">113</a>.</p> + +<p>Religion and evolution, <a href="#Page_74">74</a>.</p> + +<p>Reptiles of Mesozoic, <a href="#Page_179">179</a>.</p> + +<p>Reproduction, asexual and sexual, <a href="#Page_194">194</a>.<br /> + <span class="indent1">in fishes, <a href="#Page_196">196</a>.</span><br /> + <span class="indent1">in frogs, <a href="#Page_199">199</a>.</span><br /> + <span class="indent1">in reptiles, <a href="#Page_202">202</a>.</span></p> + +<p>Rhinoceros horn, <a href="#Page_123">123</a>.</p> + +<p>Romanes and isolation, <a href="#Page_242">242</a>.</p> + +<p>Rooster finer than hen, <a href="#Page_132">132</a>.</p> + + +<h3>S</h3> + +<p>Saint Augustine and evolution, <a href="#Page_11">11</a>.</p> + +<p>Salamanders, <a href="#Page_176">176</a>.</p> + +<p>Sargent's picture, <a href="#Page_289">289</a>.</p> + +<p>Science and the book, <a href="#Page_274">274</a>.</p> + +<p>Science and theology, <a href="#Page_280">280</a>.</p> + +<p>Science, definition, <a href="#Page_280">280</a>.</p> + +<p>Seals and polygamy, <a href="#Page_139">139</a>.</p> + +<p>Sealskin and fur, <a href="#Page_100">100</a>.</p> + +<p>Sedgwick and Darwin, <a href="#Page_24">24</a>.</p> + +<p>Selection and evolution, <a href="#Page_56">56</a>.</p> + +<p>Sexual selection, <a href="#Page_126">126</a>, <a href="#Page_128">128</a>.</p> + +<p>Skunk's odor, <a href="#Page_117">117</a>.</p> + +<p>Sloth and megatherium, <a href="#Page_29">29</a>.</p> + +<p>Song and mating, <a href="#Page_133">133</a>.</p> + +<p><a name="sparrow_english" id="sparrow_english"></a>Sparrow, English, adapted to town, <a href="#Page_66">66</a>.<br /> + <span class="indent1">and hawks, <a href="#Page_69">69</a>.</span><br /> + <span class="indent1">and winter, <a href="#Page_73">73</a>.</span><br /> + <span class="indent1">eat varied food, <a href="#Page_71">71</a>.</span><br /> + <span class="indent1">eye-minded, <a href="#Page_78">78</a>.</span><br /> + <span class="indent1">feed young on insects, <a href="#Page_72">72</a>.</span><br /> + <span class="indent1">good qualities, <a href="#Page_85">85</a>.</span><br /> + <span class="indent1">has reached limit, <a href="#Page_85">85</a>.</span><br /> + <span class="indent1">in Philadelphia, <a href="#Page_63">63</a>.</span><br /> + <span class="indent1">introduction, <a href="#Page_62">62</a>.</span><br /> + <span class="indent1">lives near houses, <a href="#Page_70">70</a>.</span><br /> + <span class="indent1">nests early, <a href="#Page_81">81</a>.</span><br /> + <span class="indent1">nests often, <a href="#Page_82">82</a>.</span><br /> + <span class="indent1">once migratory, <a href="#Page_80">80</a>.</span><br /> + <span class="indent1">quarrels without animosity, <a href="#Page_75">75</a>.</span><br /> + <span class="indent1">sociable, <a href="#Page_74">74</a>.</span><br /> + <span class="indent1">spread of, <a href="#Page_65">65</a>.</span><br /> + <span class="indent1">stays over winter, <a href="#Page_79">79</a>.</span><br /> + <span class="indent1">successful, <a href="#Page_83">83</a>.</span><br /> + <span class="indent1">transported in cars, <a href="#Page_67">67</a>.</span><br /> + <span class="indent1">unafraid of man, <a href="#Page_69">69</a>.</span><br /> + <span class="indent1">wintering, <a href="#Page_73">73</a>.</span></p> + +<p><span class="pagenum"><a name="Page_298" id="Page_298">[Pg 298]</a></span>Sparrow, House, <a href="#Page_62">62</a>.</p> + +<p>Sphex wasp, <a href="#Page_143">143</a>.</p> + +<p>Spider cocoons, <a href="#Page_139">139</a>.</p> + +<p>Spider, young, <a href="#Page_140">140</a>.</p> + +<p>Spontaneous generation, <a href="#Page_159">159</a>.</p> + +<p>Stone lilies, <a href="#Page_171">171</a>.</p> + +<p>Story of the horse, <a href="#Page_220">220</a>.</p> + +<p>Struggle against enemies, <a href="#Page_104">104</a>.<br /> + <span class="indent1">for food, <a href="#Page_91">91</a>.</span><br /> + <span class="indent1">for shelter, <a href="#Page_92">92</a>.</span><br /> + <span class="indent1">for the individual, <a href="#Page_90">90</a>.</span><br /> + <span class="indent1">for the species, <a href="#Page_91">91</a>, <a href="#Page_125">125</a>.</span></p> + +<p>Sunfish and young, <a href="#Page_196">196</a>.</p> + + +<h3>T</h3> + +<p>Taste of toad, <a href="#Page_118">118</a>.</p> + +<p>Teeth of mammals, <a href="#Page_98">98</a>.</p> + +<p>Temperature of mammals, <a href="#Page_99">99</a>.</p> + +<p>Tertiary era, <a href="#Page_185">185</a>.</p> + +<p>Thayer, concealing color, <a href="#Page_115">115</a>.</p> + +<p>Theology and science, <a href="#Page_280">280</a>.</p> + +<p>Theology, definition, <a href="#Page_280">280</a>.</p> + +<p>Thomas Aquinas and evolution, <a href="#Page_12">12</a>.</p> + +<p>Three-toed horse, <a href="#Page_227">227</a>.</p> + +<p>Toad, bad taste, <a href="#Page_118">118</a>.<br /> + <span class="indent1">color, <a href="#Page_112">112</a>.</span><br /> + <span class="indent1">enemies, <a href="#Page_113">113</a>.</span><br /> + <span class="indent1">short tadpole stage, <a href="#Page_112">112</a>.</span></p> + +<p>Tomato worm, <a href="#Page_142">142</a>.</p> + +<p>Turtles and young, <a href="#Page_202">202</a>.</p> + +<p>Tusks of elephant, <a href="#Page_124">124</a>.</p> + +<p>Tussock worm, <a href="#Page_64">64</a>.</p> + +<p>Two methods of reproduction, <a href="#Page_194">194</a>.</p> + +<p>Types of insect mouth, <a href="#Page_93">93</a>.</p> + + +<h3>U</h3> + +<p>Understanding the Bible, <a href="#Page_281">281</a>.</p> + +<p>Underwing moth, <a href="#Page_130">130</a>.</p> + + +<h3>V</h3> + +<p>Variation and natural selection, <a href="#Page_49">49</a>.<br /> + <span class="indent1">by crossing, <a href="#Page_53">53</a>.</span></p> + +<p>Virchow and man's ancestry, <a href="#Page_187">187</a>.</p> + +<p>Vireo's color, <a href="#Page_115">115</a>.</p> + + +<h3>W</h3> + +<p>Wagner and isolation, <a href="#Page_241">241</a>.</p> + +<p>Wallace and evolution, <a href="#Page_39">39</a>.</p> + +<p>Warm-blooded animals, <a href="#Page_99">99</a>.</p> + +<p>Weissman and evolution, <a href="#Page_235">235</a>.</p> + +<p>Wilberforce, Bishop, and evolution, <a href="#Page_41">41</a>.</p> + +<p>Wintering of ground hog, <a href="#Page_103">103</a>.</p> + +<p>Wintering of mammals, <a href="#Page_103">103</a>.</p> + +<p>Wintering of squirrels, <a href="#Page_103">103</a>.</p> + +<p>Woodchuck, <a href="#Page_103">103</a>.</p> + +<p>Woodpecker's nest, <a href="#Page_146">146</a>.</p> + + +<h3>Y</h3> + +<p>Young growing finer, <a href="#Page_272">272</a>.</p> +</div> + + + +<div class="section_break"></div> +<p><span class="pagenum"><a name="Page_299" id="Page_299">[Pg 299]</a></span></p> +<h2>APPENDIX</h2> + +<p class="chapter_subhead"><span class="smcap">Bibliography</span></p> + + +<p>In connection with each chapter, wherever this is possible, there are +four classes of references. First is named a small and inexpensive but +satisfactory book on the subject. Second, a more comprehensive book, +readily accessible and not unduly expensive. Then a few of the most +satisfactory reference books on the subject independent of cost or +ready availability. Fourth, a list of references to articles in the +eleventh edition of the Encyclopedia Britannica.</p> + + +<p><span class="smcap"><a href="#Page_7">Chapter I</a>.</span> <em>Evolution before Darwin.</em></p> + +<ul> +<li>1. — — — —</li> + +<li>2. Biology and Its Makers, Locy.</li> + +<li>3. From the Greeks to Darwin, Osborn. Chapters 1, 2, 3, 19.</li> + +<li>4. Encyclopedia Britannica, 11th edition, article, <em>Evolution</em>, +section, <em>History</em>.</li> +</ul> + + +<p><span class="smcap"><a href="#Page_21">Chapter II</a>.</span> <em>Darwin and Wallace.</em></p> + +<ul> +<li>1. The Coming of Evolution, Judd.</li> + +<li>2. Charles Darwin, Poulton.</li> + +<li>3. Life and Letters of Charles Darwin, by his son, Francis Darwin. 2 +vols.</li> + +<li>My Life, A. R. Wallace. 2 vols.</li> + +<li>4. Encyclopedia Britannica, articles <em>Darwin</em>, <em>Wallace</em>.</li> +</ul> + + +<p><span class="pagenum"><a name="Page_300" id="Page_300">[Pg 300]</a></span><span class="smcap"><a href="#Page_44">Chapter III</a>.</span> <em>The Underlying Idea.</em></p> + +<ul> +<li>1. Evolution, Geddes and Thompson.</li> + +<li>2. The Origin of Species, Charles Darwin.</li> + +<li>3. The Evolution Theory, Weissmann. 2 vols.</li> + +<li>4. Encyclopedia Britannica, articles <em>Variation</em> and <em>Selection</em>.</li> +</ul> + + +<p><span class="smcap"><a href="#Page_87">Chapter IV</a>.</span> <em>Adaptation for the Individual.</em></p> + +<ul> +<li>1. Colin Clout's Calendar, Grant Allen.</li> + +<li>2. Evolution and Animal Life, Jordan and Kellogg. Chapters 16, 19.</li> + +<li>3. Darwinism, Wallace.</li> + +<li>4. Encyclopedia Britannica, articles <em>Adaptation</em>, <em>Colours of +Animals</em>, <em>Hibernation</em>.</li> +</ul> + + +<p><span class="smcap"><a href="#Page_125">Chapter V</a>.</span> <em>Adaptation for the Species.</em></p> + +<ul> +<li>1. Colin Clout's Calendar, Grant Allen.</li> + +<li>2. Evolution and Animal Life, Jordan and Kellogg.</li> + +<li>3. Darwinism, Wallace.</li> + +<li>4. Encyclopedia Britannica, articles, <em>Metamorphosis</em>, <em>Song of +Birds</em>.</li> +</ul> + + +<p><span class="smcap"><a href="#Page_149">Chapter VI</a>.</span> <em>Life in the Past.</em></p> + +<ul> +<li>1. The Story of Our Continent, Shaler.</li> + +<li>2. Elements of Geology, Blackwelder and Barrows.</li> + +<li>3. The Story of Evolution, McCabe.</li> + +<li>4. Encyclopedia Britannica, article, <em>Geology</em> (palæontological and +physiographical).</li> +</ul> + + +<p><span class="smcap"><a href="#Page_192">Chapter VII</a>.</span> <em>How the Mammals Developed.</em></p> + +<ul> +<li>1. — — — —</li> + +<li><span class="pagenum"><a name="Page_301" id="Page_301">[Pg 301]</a></span>2. Plant and Animal Children, Torelle.</li> + +<li>3. — — — —</li> + +<li>4. Encyclopedia Britannica, article, <em>Mammalia</em>.</li> +</ul> + + +<p><span class="smcap"><a href="#Page_220">Chapter VIII</a>.</span> <em>The Story of the Horse.</em></p> + +<ul> +<li>1. The Evolution of the Horse in America, Osborn, in <em>The Century</em>, +November, 1904.</li> + +<li>The Evolution of the Horse, Matthew.</li> + +<li>2. The Horse, Flower.</li> + +<li>3. Encyclopedia Britannica, article, <em>Horse</em>.</li> +</ul> + + +<p><span class="smcap"><a href="#Page_233">Chapter IX</a>.</span> <em>Evolution Since Darwin.</em></p> + +<ul> +<li>1. The Evolution of Living Organisms, Goodrich.</li> + +<li>2. Biology and Its Makers, Locy. Chapters 14, 18.</li> + +<li>3. Darwinism To-day, Kellogg.</li> + +<li>4. Encyclopedia Britannica, articles, <em>Romanes</em>, <em>Weissmann</em>, +<em>Mendel</em>.</li> +</ul> + + +<p><span class="smcap"><a href="#Page_249">Chapter X</a>.</span> <em>The Future Evolution of Man.</em></p> + +<ul> +<li>1. The Problem of Race Regeneration, Ellis.</li> + +<li>2. Inquiries into Human Faculty, Galton.</li> + +<li>3. Heredity, Thompson.</li> + +<li>4. Encyclopedia Britannica, articles, <em>Eugenics</em>, <em>Galton</em>.</li> +</ul> + + +<p><span class="smcap"><a href="#Page_274">Chapter XI</a>.</span> <em>Science and the Book.</em></p> + +<ul> +<li>1. — — — —</li> + +<li>2. The Origin and Permanent Value of the Old Testament, Skater.</li> + +<li>3. The Life and Literature of the Ancient Hebrews, Abbott.</li> + +<li><span class="pagenum"><a name="Page_302" id="Page_302">[Pg 302]</a></span>4. Encyclopedia Britannica, articles, <em>Genesis</em>, <em>Bible</em> (Old +Testament Canon).</li> +</ul> + + +<h3><span class="smcap">Review Questions</span></h3> + +<p><em><a href="#Page_1">Foreword</a>.</em> 1. What is the purpose of this book?</p> + +<p><a href="#Page_7">Chapter I</a>. 1. What were some of the theories of the Greek +philosophers, and what shadowing of truth was there in their beliefs? +2. What was Lucretius's idea? 3. What were the explanations of Genesis +given by St. Augustine and by Thomas Aquinas? 4. What were theories of +Descartes, Leibnitz, and Kant? 5. How is the delay of the thought of +evolution accounted for? 6. What were the contributions of Linnæus, +Buffon, Erasmus, Darwin, Lamarck? 7. What check to progress was made +by Cuvier and Agassiz? 8. What phases of evolution were studied by +Goethe?</p> + +<p><a href="#Page_21">Chapter II</a>. 1. Sketch the life of Charles Darwin. 2. What advantages +did he derive from the "Beagle" expedition? 3. What is the theory of +Natural Selection, and how did Darwin arrive at it? 4. Describe the +Wallace and Wilberforce incidents. 5. What has been the progressive +attitude toward the Darwinian idea?</p> + +<p><a href="#Page_44">Chapter III</a>. 1. Explain Heredity as the conservative force of nature. +2. Explain Variation as the progressive tendency in nature. 3. In what +ratio is the Multiplication of animals? 4. How does the process of +Selection make for the survival of the fittest? 5. What three +possibilities are open to animals<span class="pagenum"><a name="Page_303" id="Page_303">[Pg 303]</a></span> under a change of environment? 6. +What is the history of the English Sparrow in this country, and how is +his increase accounted for by his powers of adaptation?</p> + +<p><a href="#Page_87">Chapter IV</a>. 1. Show how the struggle for existence as affecting food, +results in adaptations in the individual. Give illustrations. 2. Do +the same for the results of struggle for shelter. 3. What are some of +the adjustments resulting from the need of protection from foes?</p> + +<p><a href="#Page_125">Chapter V</a>. 1. Discuss coloration. 2. How is sound used as an +attraction? 3. What are some of the other methods of attracting mates? +4. What are some of the specializations produced by polygamy? 5. +Describe some of the protections and provisions for the young.</p> + +<p><a href="#Page_149">Chapter VI</a>. 1. What is La Place's Nebular Hypothesis? 2. What is the +Planetesimal Theory? 3. What bases have been used for calculation of +the age of the earth? 4. Reproduce the <a href="#geological_times">Table of Geological Times</a>. 5. +What is the Theory of Spontaneous Generation? 6. What is the theory of +life development from organic dust in space? 7. Discuss protoplasm. 8. +What was the probable growth of the North American continent? 9. What +is the nature of the fossils in the earliest layers of stratified +rock? 10. Describe the life of each of the three periods of the +Palæozoic era. 11. Do the same for the Mesozoic era. 12. What was the +effect upon life of the development of seasons and of climates? 13. +What physical characteristics of the earth helped in the development +of new animal<span class="pagenum"><a name="Page_304" id="Page_304">[Pg 304]</a></span> forms in the Cenozoic era? 14. What has been the ascent +of man?</p> + +<p><a href="#Page_192">Chapter VII</a>. 1. Illustrate the asexual method of reproduction. 2. +Trace the two-parent method of reproduction upward from the simplest +forms. 3. What has been the development of the milk glands? 4. How +does the prolonged care of the young by the mother indicate the higher +development of the animal?</p> + +<p><a href="#Page_220">Chapter VIII</a>. 1. Describe the earliest known ancestor of the horse? 2. +What changes took place in the second stage of development? 3. What is +the form by the middle of the Tertiary period? 4. What was the size of +the late Tertiary horse, and how was the grinding power of the teeth +increased? 5. How was the early Quaternary horse adapted for speed and +for eating? 6. How is the extermination of the horse in North and +South America accounted for, and how was he introduced again?</p> + +<p><a href="#Page_233">Chapter IX</a>. 1. How extensive has the belief in evolution become since +Darwin's day? 2. How does the theory of Natural Selection fail in +accounting for Variation; how did Darwin try to amend his original +theory; and what is Weissmann's belief. 3. What second objection has +been brought against the theory of Natural Selection, and what have +been the contributions of Wagner, Jordan, and Romanes to the +discussion? 4. What is the third objection to Darwinism, and what is +the bearing upon it of the theory of Orthogenesis? 5. What is the +American and French tendency toward the belief that use is the cause +of the persisting of organs? 6. How did DeVries discover<span class="pagenum"><a name="Page_305" id="Page_305">[Pg 305]</a></span> the +principle of mutation, and how does it apply to the discussion of +evolution?</p> + +<p><a href="#Page_249">Chapter X</a>. 1. What was the cause of the passing of the civilization of +Athens, of Judea, of Sparta? 2. What promise of uniform development is +evident to-day, and what are some of the hindrances? 3. What has been +the changing emphasis in the evolution of man? 4. How is man the +arbiter of his own destiny? 5. What is the task of the eugenist; how +is he trying to accomplish it, and what are some of the possibilities +suggested. 6. What is the promise for the future?</p> + +<p><a href="#Page_274">Chapter XI</a>. 1. What is the duty of the fair-minded person toward the +essential truths of religion and of science? 2. What two difficulties +lie in the path of reconciliation, and why should each century restate +its truths? 3. What three steps are desirable in studying the Bible? +Illustrate. 4. What is the essential truth of the early chapters of +Genesis, and what its glory? 5. Interpret the meaning of "creation of +man in God's image." 6. What is our duty to ourselves and our +children?</p> + + + + + + + + +<pre> + + + + + +End of the Project Gutenberg EBook of The Meaning of Evolution, by +Samuel Christian Schmucker + +*** END OF THIS PROJECT GUTENBERG EBOOK THE MEANING OF EVOLUTION *** + +***** This file should be named 29422-h.htm or 29422-h.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/2/9/4/2/29422/ + +Produced by Juliet Sutherland, Chris Logan and the Online +Distributed Proofreading Team at http://www.pgdp.net + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. 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You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: The Meaning of Evolution + +Author: Samuel Christian Schmucker + +Release Date: July 16, 2009 [EBook #29422] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK THE MEANING OF EVOLUTION *** + + + + +Produced by Juliet Sutherland, Chris Logan and the Online +Distributed Proofreading Team at http://www.pgdp.net + + + + + + + + + +THE MEANING OF +EVOLUTION + +BY + +SAMUEL CHRISTIAN SCHMUCKER, PH.D. + +PROFESSOR OF BIOLOGICAL SCIENCES IN THE +WEST CHESTER STATE NORMAL SCHOOL +WEST CHESTER, PA. + +[Illustration] + +The Chautauqua Press +CHAUTAUQUA, NEW YORK +MCMXIII + + + + +COPYRIGHT, 1913 +BY THE MACMILLAN COMPANY + + +Set up and electrotyped. Published June, 1913 + + + + +CONTENTS + + + CHAPTER PAGE + + A FOREWORD 1 + + I. EVOLUTION BEFORE DARWIN 7 + + II. DARWIN AND WALLACE 21 + + III. THE UNDERLYING IDEA 44 + + IV. ADAPTATION FOR THE INDIVIDUAL 87 + + V. ADAPTATION FOR THE SPECIES 125 + + VI. LIFE IN THE PAST 149 + + VII. HOW THE MAMMALS DEVELOPED 192 + + VIII. THE STORY OF THE HORSE 220 + + IX. EVOLUTION SINCE DARWIN 233 + + X. THE FUTURE EVOLUTION OF MAN 249 + + XI. SCIENCE AND THE BOOK 274 + + INDEX 293 + + APPENDIX 299 + + + + +A FOREWORD + + +Before my window lies an enchanting landscape. It embraces a stretch +of open rolling country, beautiful as the eye could wish to rest upon. +The sun with its slanting rays is not giving it heat enough in these +winter months to make it blossom in its radiant beauty, but the mind +goes easily back through the few brown months to the time when the +field not far away was waving with its rich yellow grain so soon to be +food for those who planted it. Beyond this field lies an orchard +where, in regular and orderly rows, stand the apple trees whose bright +blossoms in the spring make the landscape so beautiful and whose fruit +in the fall serves so richly for our enjoyment. A little farther on, a +pasture is filled with sleek-coated cows, feeding quietly and +patiently until the evening when they will return to their stalls to +yield their rich milk. Still farther on lies a tract of forest. The +varied shades of the beeches, the tulip poplars and the chestnuts make +an exquisite contrast and give to the landscape its attractive +background framed in by a distant hill. Behind this hill flows a +mighty river carrying on its breast the ships by which we share the +over-abundance of our own blessings with our brothers on the other +side of the sea, from whom in turn we receive of their overplus. +Beyond this teeming river lies a level stretch of fertile land and +then the mighty ocean. On one side of the scene runs a busy highway. +Along this men pass and repass, some on foot, others drawn by their +patient and submissive horses. Still others are carried by the +new-found power of the sunshine imprisoned beneath the rocks in the +oil that has been forming ever since the sun shone down upon the great +forests of the far distant past. + +In a pathway to one side, some children are playing. One of them has +laid upon the ground a rectangle of stones divided into four and her +little mind sees before her the house which is teaching her to get +ready for the work that shall come to her in later life. Meanwhile her +short-haired companion is prancing around astride a stick; he too, +little as he suspects it, is getting ready for life. + +It needs little reflection to realize that the scene has not always +been what it is. The underlying ground has surely been there longest, +its age vying only with that of the bounding ocean that beats upon the +shore and works the sand into fantastic stretches. The forest has been +there long and so has the stream; the road perhaps ranks next in age; +then come the orchard trees, and most recent of all the waving grain. +People come and go but form no stable part of this landscape. We know +how the grain came to be there, and we understand the orderly +arrangement of the orchard trees; the road too we can explain. How +came the stream there, and how the forest trees? Have they always been +there, or did they too have a beginning? Was there a time when there +was no ocean? When was this time? How came they there? + +When the lisping lips of my young child asked me, "Papa, who made me?" +I told him "God," and he knew enough and was content with his +knowledge. After a while he grew older and his inquisitive spirit +began to puzzle with the question of how God had made him. When his +growing mind was ready for the new knowledge I took him to my side and +told him the great mystery of life. I told him how he owed to his +father and to his mother the beginnings of his life, how God gave him +to us. Now a new era opened in his childish mind. As he grows on to +greater maturity he cannot help wondering how the first man was made, +how the trees, and the world came to be. He is no longer satisfied +with the simple statement that God made them. His eager mind wants to +know, if may be, how God made them. + +So, in the distant past, in the childhood of our race, the question +was asked, "Who made us?" and the answer was "God." Men formed their +simple conception at that time of how He did it. As the centuries +rolled by and the children of men have learned from creation the story +of its origin a riper and richer knowledge has given them a broader +and finer conception. No less does the reverent student believe that +God created the earth, but he no longer thinks of God as working, as +man works. He no longer feels that it is impious to attempt to read +God's plan in His work; to see how this work has arisen, to see, if +may be, what there is ahead. + +This is one of the tasks to which science is now giving itself. The +answer is uncertain and halting. A few things seem clear; others seem +to be nearly certain; of still others we can only say that for the +present we must be content with the knowledge we have. But if we take +the best we have and work over it thoughtfully and carefully, the +better will slowly come, and in time we shall know far more than we +now suspect. Meanwhile, it is the attempt of this book to give to +people whose training is other than scientific some conception of this +great story of creation. Without dogmatic certainty but without +indecision it tries to tell what modern science thinks as to the great +problems of life. It tries to describe the possible origin of animals +and plants, their slow advance, the length of their steady uplift, the +forces that brought it about. It tries to tell a little of the men +who have helped to develop the great idea of evolution, of the great +men who persuaded the scientific world of its truth, and of the later +minds that are modifying and enlarging the idea of the master +evolutionist. It tries to tell what science perhaps vaguely hopes as +to the future. What are we to be? Can we help the great advance? + + + + +The Meaning of Evolution + + + + +CHAPTER I + +EVOLUTION BEFORE DARWIN + + +Ever since men have been able to think they must have puzzled out for +themselves some way of accounting for their own beginnings. Every +savage tribe with whom we have any intimate acquaintance has some +story that accounts for the origin of the tribe at least, and often +for the beginning of the world. These stories are handed down from +generation to generation and are scarcely questioned in the thought of +most men. In early Greece there was a succession of men whom the world +calls philosophers. These men thought earnestly and deeply on all +kinds of questions. Their method was not our method. The plan of +making a long series of observations, before coming to any conclusion, +was not the habit of their minds. They reasoned out on general +principles what seemed to them must have been the origin of the world. +It is not strange that among these should come, now and then, some one +who in some passage or other should show that there had come to his +mind at least a glimmer of the thought that was later to develop into +the great idea which the modern world calls evolution. + +Among the earliest of these was Anaximander, who lived 600 years +before Christ. He thought that the earth was at first a fluid. +Gradually this fluid began to dry and grow thicker, and here and +there, where it thickened most, dry land appeared. When this dry land +had become firm enough to serve as his home, man came up from the +water in the form of a fish. Slowly and gradually the fish, struggling +about on the land, gained for himself the limbs and members he needed +for his new situation and developed into a man. After him other +animals came up in much the same fashion, then the plants, until the +whole world was clothed with its present inhabitants. + +One hundred and fifty years later Empedocles announced a new thought. +He said that in the beginnings there were all sorts of strange, +incomplete, and misjointed monsters which swarmed upon the earth, +having sprung up out of the earth itself. Each was a chaos of the +limbs which afterward were to belong to other animals which needed +them more. Slowly and gradually an interchanging came about by which +appropriate limbs fastened themselves to the proper animals. The last +of these misjointed creatures is the one known as the centaur, +half-man--half-horse. After a while, when all the members had found +their proper places, the animals were complete. In one respect this +opinion foreshadowed our later idea. It suggested that the more +perfect animals had arisen out of the less perfect and that the change +came gradually. + +Then came Anaxagoras, who was the first to believe that there was +intelligent design back of the creation of animals and of plants. He +thought there had originally been a slime in which were the germs of +all the later plants, animals, and minerals, mixed in a chaos. Slowly +order arose. Out of the mixture settled first the minerals forming the +earth, with the air floating above it, and above the air was the +ether. Out of the air the germs of plants settled upon the earth, and +vegetation covered the mineral floor. Then from the ether came the +germs of animals and of men. These settled among the plants and sprang +up into the animals of the world, as well as the people. + +The greatest scientific thinker of early Greece was Aristotle. He had +lived by the seashore and knew better than any other man of his times +the exquisite seaweeds and the still more beautiful marine animals. He +was the first to think of them as a linked series, the higher +developing out of the lower under the pressure of what he called a +perfecting principle. Out of the inanimate rocks had sprung the marine +plants--the seaweeds. From these had developed first "plant animals" +like the sea anemones and the sponges. These grew attached to the +rocks, as plants do. With higher development came locomotion, with +ever-increasing energy. At last man arose, the crown of all creation. +Presiding over all this advance is the "efficient cause," God. +Aristotle rejected entirely the earlier ideas that any of this work +came about by chance. He was certain of the existence of plan and +purpose in the development. + +Just a little before the time of Christ the Latin poet, Lucretius, +wrote a poem on "The Nature of Things." Here he describes how in the +early years the beginnings of things in small, disjointed fashion +moved about among each other at first in utter confusion, each trying +itself with the other. After many trials the proper members came +together. When they had been thus placed the warmth of the sun shining +down upon the earth helped the earth to reproduce the same sort of +creatures. So living things came up and flourished. The poem expresses +many beautiful ideas, but the underlying conceptions lack the unity +and grandeur that marked Aristotle's work, which later was the potent +influence in shaping men's minds. It died out after a while, only to +awake in the Renaissance with marvelous vitality, starting the world +to think afresh great thoughts that would not die, but would grow from +that time on with ever-widening scope. + +Among the Jews and early Christians the stately and beautiful account +in Genesis sufficed for all the needs of minds fully occupied with +other questions. With the growth of philosophy among Christian minds +again came the need of a satisfactory solution. St. Augustine was +probably the greatest of the so-called "Fathers" of the church. His +mind was eminently philosophical, and he was learned in the writings +of the older Greeks. He believed the language of Genesis to mean that +in the beginning God planted in chaos the seed that afterward sprang +up into the heavens and the earth. He further says that the six days +of creation were not days of time, but a series of causes, and that, +in the order described as these six days, God planted in chaos the +various beginnings of things. These in the fullness of time sprang up +into the world as we know it now. The problem was not a question about +which the church cared to trouble itself, and with the oncoming of the +Dark Ages the whole matter dropped nearly out of the thoughts of men. + +When the times began to lighten we find the schoolmen, among the +greatest of whom was Thomas Aquinas. Referring especially to the +authority of his master, St. Augustine, he says that it would be easy +mistakenly to believe that the author of Genesis meant to convey the +idea that on each of the six days certain acts of creation were +performed. It is quite evident, thinks Aquinas, that in those early +times God only created the germs of things and put into the earth +powers which should later become active. After the Creator had thus +endowed the earth he rested from the work, which proceeded to develop +under the influence of these first germs. + +Nearly four hundred years later, when Europe had finally awakened out +of the deep and refreshing sleep in which it had fortunately forgotten +much of the past, a new era dawned and modern thought began. +Immediately men commenced to busy their minds with broader problems +than they had been discussing since the time of the Greek +philosophers. The hand of tradition, however, was heavy on them still. +They dreaded to run counter to authority, and did not dare think +unrestrainedly. Descartes shows us how we can understand things better +if we will imagine a few principles by which it will be easy to +account for things as they are. Then he carefully elaborates these +principles as they occur to him; but he has no sooner done so than he +takes care to add, "Of course, we know the earth was not made in this +way." + +A little later the philosopher, Leibnitz, believed in an orderly +creation that had advanced by regular degrees, and that the lower +animals had thus developed into the higher. He adds interestingly that +there are probably on some other planets animals midway between the +ape and man, but that nature has kindly removed such animals from the +earth in order that man's superiority to the apes should be entirely +beyond question. + +By the middle of the eighteenth century men had begun to think more +fearlessly. The great Emanuel Kant wrote in his younger and less timid +years, "The General History of Nature and Theory of the Heavens." The +great Newton had by his law of gravitation brought order into the +heavens. Kant looked longingly for a greater Newton, who should find a +similar unity in the animal world. He saw the wonderful likenesses +between animals that the anatomist, Buffon, had recently pointed out. +He believed there must somehow be blood relationship between all +animals. He tried hard to conceive of some underlying natural cause by +which all could have come about. As he grew older and his mind became +more cautious he came to think the matter deeper than the human mind +could ever fathom. He gave up the hope and believed the problem of +animal origin and derivation would forever remain insoluble. He +feared there was not in man the power to conceive his own origin. + +If we ever wonder why it took so long before the thought of evolution +should have fully dawned upon the world, the answer is not far to +seek. No student of Natural History in ancient or medieval times had +the faintest conception of the enormous number of animals and of +plants in the world. The old Greek or Roman student of Natural History +gives no evidence of knowing more than a few hundred animals. Men have +named to-day, with systematic Latin names, hundreds of animals for +every one that Pliny ever knew, and he knew more than any other man of +early times of whom record has come to us. + +In early days men who traveled into foreign countries brought back +accounts of what they saw. The whole Natural History of ancient times +was filled with the most absurd and ludicrous stories of all sorts of +things to be seen in distant lands. Sir John Mandeville tells tales +almost as imaginative and quite as amusing as those attributed to +Baron Munchausen. + +Upon the great awakening of the fifteenth century, with its new study +and its wide-ranging travel, an entire change came over the human +mind. Men who journeyed into far countries brought back with them not +only accounts of what they saw, but, so far as might be, the things +themselves. Collections of plants and of such parts of animals as +could be readily preserved soon began to accumulate in every great +center of Europe. It was only a question of time when such +acquisitions must be arranged and classified, but as yet there was no +system by which this could be done. The great Swedish botanist, +Linnaeus, who lived in the eighteenth century, first taught us to give +to each animal and plant two Latin names, the first of these to be the +name of the group, known as a genus, to which it belongs, the second +to be the name of that sort, or species, of animal. The cat, for +instance, is _Felis catus_, the lion _Felis leo_, the tiger _Felis +tigris_, and so on. Linnaeus then arranged the genera (plural of genus) +into families, and these families into orders and so classified the +animal and plant world as far as he knew it. In his earlier years +Linnaeus thought of each species as being utterly apart and distant +from any other. He believed it had been so from the first, each +species having sprung in its complete form from the creative hand of +God. In later life he came to show some evidence of the belief in +development, but his great work is all built on the idea of the entire +fixity of species. + +About this time we find in the writings of Buffon, the French +naturalist, many indications of an idea approaching our modern +conceptions of evolution. He felt sure the pig could not have been a +special creation, because he had four toes, two of which, with all +their bones and their hoofs, are quite useless to him. We now call +these toes "vestigial," and know the pig's ancestors used them, +walking on four toes and not on two, as at present. Buffon believed +there were degenerations as well as developments, and considered the +ape a degenerate man. He conceived these changes to be brought about +by what he called the favors and disfavors of nature. He varied much +in his opinions in various parts of his career and occasionally is +smitten either with conscience or with fear of authority. Then he goes +back and says it is all a mistake and each animal is the product of a +special act on the part of the Creator. + +A little later, in England, Erasmus Darwin, the grandfather of Charles +Darwin, who was subsequently to establish the evolution theory, wrote +a long and elaborate poem called the "Temple of Nature." In this we +find a remarkable prevision of many of the principles which were +afterward to be warmly advocated and disputed during the growth of the +idea of evolution. + + "Hence without parents by spontaneous growth, + Rise the first specks of animated life. + + * * * * * * * + + Thus as successive generations bloom + New powers acquire and larger limbs assume." + +Erasmus Darwin recognized the struggle for existence, but he saw in it +only a check against overcrowding, and not an active factor in the +development as his grandson Charles came to see it. It is possible the +elder Darwin's views might have been taken more seriously had he not +clothed them with the form of verse. In these days it seems quite +ludicrous to think of giving to the world a new scientific concept or +a new phase of philosophy in verse. + +The beginning of the nineteenth century gives us the first really +great contribution to the idea of evolution. Under more favorable +surroundings, this idea would have budded and become the parent stock +of our modern theories. The chill frosts of adverse criticism by those +in authority in science nipped the budding idea and so set it back +that only of late years have men come to realize its strength and +power. The Chevalier de Lamarck, serving in Monaco, was attracted by +its rich flora to the study of botany. Coming later to Paris, he +became acquainted with Buffon and was led by him to publish a Flora of +France, using the Linnaean system of classification. He was appointed +to the chair of zooelogy in the Jardin des Plantes, and was given +especial charge of the invertebrate animals, comprising all the +members of the animal kingdom except those with backbones. After +seventeen years of work over these forms, during which he wrote +several books describing them, he finally published the great work on +which his fame depends. This was the "Philosophie Zooelogique." In this +treatise he taught that the animal kingdom is a unit and that all its +members are blood relations; that the members vary with varying +conditions; that this variation results in continued advance. In all +of these points Lamarck is at one with modern thought. His idea of the +method by which the variation comes about has been accepted and +rejected; modified, reaccepted, and again rejected. + +Lamarck's conception of the cause of progress was somewhat as follows: +The desire for any action on the part of an animal leads to efforts to +accomplish that desire. From these efforts came gradually the organ +and its accompanying powers. With every exercise of these powers the +organ and its corresponding function became better developed. Every +gain either in function or in organ was transmitted to those of the +next generation, who were thus enabled to start where their parents +left off. The general environment constantly gave the stimuli that led +to the adaptive changes. + +American zooelogists have been especially inclined toward Lamarck's +ideas. Until Weissmann startled the scientific world with his sharp +denial of the possibility of transmitting to offspring any growth +acquired by the parents, all seemed well. There is a tendency now to +insist once more that slowly and gradually, in some perhaps as yet +unexplained way, external factors do influence even egg cells, and +gradually acquired characters do reappear in the offspring. + +The blighting setback these views suffered came from the criticisms of +Baron Cuvier. This genuinely remarkable man had built up the study of +comparative anatomy. To him students flocked from all sides. Among +these one of the most brilliant was Agassiz, the Swiss naturalist, who +later came to this country, filled with Cuvier's ideas. This great +teacher believed that species are fixed. He knew better than any man +of his times the wonderful similarity in structure between animals of +a given class. He attributed this not to any real blood relationship +between the animals. They were alike because they had been made by the +same Creator. This great Artificer worked along four main lines, and +hence animals could be divided into four groups. Many who have studied +text books on zooelogy written in this country by Agassiz and his +followers will remember the four classes--Radiates, Articulates, +Mollusks, and Vertebrates. Agassiz was such a wonderful teacher and so +genial and so lovable a man that his opposition to evolution held back +the advance of the Darwinian idea in America as Cuvier's influence +had held back the Lamarckian idea in Europe. For the brilliant Cuvier +simply laughed before his students at each "new folly" of Buffon and +of Lamarck. Under this ridicule the influence of both men withered and +died. + +A little later the great poet, Goethe, turned his attention to the +problem of evolution, giving an interesting account of the +metamorphoses of plants. He declared, also, that the human skull is a +continuation of the backbones of the neck, and that these bones have +been transformed into the present skull. But his great genius as a +poet drew his attention into other fields. Haeckel points out that if +Goethe had known Lamarck's work his genius would have gained for the +"Philosophie Zooelogique" the interest and respect of the reading +world. But Cuvier laughed it out of court, and only in comparatively +modern times, since Darwin's work has set the world thinking anew, is +Lamarck's career recognized at its true value. Lamarck should have +been the founder of the evolution theory. But the time was not quite +ripe, and it remained for Charles Darwin to announce his idea, +sustained and fortified by years of careful observation and thoughtful +reflection. + + + + +CHAPTER II + +DARWIN AND WALLACE + + +We have seen in the last chapter that whenever men have actively +thought they have attempted to explain the origin of plants and +animals as well as of themselves. No one who wrote previous to the +time of Charles Darwin had expressed any idea concerning this matter +with force enough to convince any large portion of the thinking world. +If Lamarck had fallen on better times, if the great Cuvier had not +laughed him to scorn, if Goethe had found him out and made him known +to the world, evolution might have come into its own sooner. None of +these conditions arose, and it remained for Charles Darwin to give to +the world in clear and cogent form the thought of evolution. He +gathered so much material before he expressed his opinions, and looked +at the matter from so many sides that, when he published his results, +he had foreseen most of the objections which were subsequently to +arise in opposition to his announcement. Charles Darwin is recognized +to-day as the father of the evolutionary movement. + +It has been sometimes said in recent years that Darwinism is dead, and +there is a sense in which this is true. Unmodified and unassisted +natural selection is not to-day considered by most scientists a +sufficient agent for producing evolution. But everyone connected with +the subject acknowledges Darwin as the master, and says that it was +his work which converted the world to a belief in evolution. We can +have no better preparation for an intelligent understanding of this +subject than to consider carefully the life of this remarkable man and +the circumstances under which he came to his epoch-making conclusions. + +Evolution has taught us to attempt as far as may be to account for man +on the basis of his heredity or of his environment. It is interesting +to note that both of these factors in Darwin's case were entirely +favorable. In the latter part of the eighteenth century Erasmus Darwin +had given to the world an astonishing poem in which he anticipated not +a little of the thought which his more famous grandson was to make so +widely known. Josiah Wedgwood had learned to make for England her most +famous pottery, no quality of which was more widely recognized than +the sterling patience with which it was made. Erasmus Darwin, with his +scientific proclivities, and Josiah Wedgwood, with his sturdy common +sense and patient workmanship, united to give Charles Darwin his +inherited tastes, for he was a grandson of both. Born in 1809, on the +banks of the Severn in England, Charles Darwin was the delicate son of +a practicing physician of modest but sufficient means. Owing to his +lack of early vigor, Darwin spent much time in the open air, and in +his excursions about his home was chiefly interested in collecting +beetles. This taste, which lasted through all his young manhood, is +the one early indication of the traits that were later to develop. At +first in the day-school and later in the preparatory school Charles +Darwin was anything but a satisfactory student. Even a kindly desire +later to make the most of him makes it impossible to find traces of +any especial fondness for earnest study. He himself believed his +education to have been nearly useless, although he doubtless +under-estimated its value. At the age of sixteen he went to Edinburgh +at his father's desire, to study medicine. The sight of the +dissecting-room nauseated him completely, and he refused to continue +working in it. Later an operation which he witnessed in a clinic at +the hospital sickened him so thoroughly that he declined to attend +further operations. It became evident that the young man was not +adapted to the life of a physician. The next move was to educate him +for the church, and for this purpose, at the age of nineteen, he went +to Cambridge. Here it soon appeared that he was no better adapted to +the ministry than he was to the practice of medicine, and his +university career went on in very desultory fashion. Most of his work +was distinctly neglected, but two of the men he met there were to +influence largely his future life. Henslow, the botanist, was +unusually fond, for a professor in those days, of work in the field. +Charles Darwin's tastes coincided with those of Henslow, with whom he +formed an intimate friendship. He was always welcomed as a companion +on the field trips. Though he studied little of botany in the +classroom or laboratory, he was constantly with Henslow or with +Sedgwick in the field. Sedgwick was the professor of geology, and of +him Darwin was particularly fond, and under him did much the largest +amount of his study. When he came up for graduation he ranked tenth of +those who "did not go in for honors," a not very remarkable class +standing. He was still required to put in two years of residence, and +during this interval he spent most of his time with Sedgwick in the +study of geology in the field. Returning to his home after a +geological trip into Wales, Darwin found awaiting him a letter from +Henslow, offering him an appointment that opened to his ardent mind +the door to a career after his own heart. + +The British nation, being the greatest commercial nation of the globe, +has the greatest need for accurate charts of all the seas. Frequently +she has sent out great charting expeditions to various parts of the +world. One of these was to go out in Her Majesty's ship, _Beagle_, for +a voyage around the world. Captain Fitzroy was in command, and he was +especially commissioned to map the coast of South America from La +Plata to Cape Horn and up the western side. In addition to this work, +by carrying a set of accurate chronometers, he was to check up the +longitude of the various ports to be visited in this circumnavigation +of the globe. It was customary on such expeditions to carry a young +man whose duty it was to study the natural history of the countries +visited on the trip. The salary of such a naturalist was so small that +an experienced man could scarcely afford to take the place. Therefore +the appointment usually went to a man rather of promise than of +achievement. Through Henslow's influence, Charles Darwin was offered +this position in 1831. Darwin hastened to obtain his father's +permission, but the elder Darwin at first declined to consider the +matter. He felt that his son had not made such use of his time at the +university as warranted the hope that much could be expected of such a +journey. He believed it necessary that Charles should have some means +of earning an adequate living before he could think of devoting his +time to science. Charles found an efficient advocate in the person of +his uncle, Josiah Wedgwood, Jr. Together they persuaded the father of +the propriety of giving to Charles this opportunity to follow out his +real tastes and ambitions. Accordingly, at the age of twenty-two, we +find him embarked on a journey around the world. In the cabin of the +_Beagle_ he had abundant time, in his long sail across the Atlantic, +to read the two volumes of Lyell's "Elements of Geology," which +Henslow had handed him, with the suggestion that he read it, but on no +account believe it. Filled with the love of geology as Darwin was, +this epoch-making book was exactly the stimulus needed. Lyell had just +begun to persuade the world that to understand the past we must study +the present. In the forces now at work he saw cause enough to account +for all the history of the past of the earth. + +There is little doubt that this book was one of the most potent +factors in determining the bent of Darwin's mind. His entire +educational experience had failed to appeal to him. It is fortunate, +we now know, that this was the case. If the university course of the +time had really seized him it would have made but one more student +like hundreds it was turning out each year. For most of us this is the +happy event. Now and then comes the rare spirit to whom all of this +fails to appeal because he is ready for something better. Such was the +spirit of Charles Darwin. He started on his journey with a mind +singularly free from prepossessions. In the long hours of this sailing +voyage across the Atlantic Ocean Darwin had time to read and ponder +Lyell's weighty words. By the time he reached the Brazilian shore he +was filled with Lyell's conception that the present is the child of +the past, developing out of it in orderly sequence. Lyell expressly +denied that this is true of the animal and plant world. He applied it +only to the face of the earth, with its mountains of uplift and its +valleys of erosion. But the underlying principle of an orderly +development under the action of natural causes was there. In Darwin's +mind this at once found acceptance, and was destined to a fruition its +author had expressly disclaimed. + +The narrative of this voyage, as subsequently written, describes the +islands visited by the _Beagle_ in crossing the Atlantic Ocean. The +contrast between the simple and general interest in these islands and +the care with which Darwin described the Galapagos and the Keeling +Atoll visited later in the voyage are speaking evidence of the rapid +development going on in the mind of the young naturalist. + +Reaching the shore of South America, Darwin first turns to its +geology. But before long the animal life attracts his attention. In +the Brazilian forest Darwin had his first experience of the wealth of +animal and plant life in the tropics, and, like all naturalists, he +was very enthusiastic over it. Among the animals that particularly +attracted his attention was the sloth, a peculiar creature climbing +slowly about the trees, small of size and sluggish of habit. Another +animal that interested him greatly was the little armadillo with its +interesting habit of curling up in its plated skin. + +Captain Fitzroy soon finished what work he was required to do in this +neighborhood, and Darwin was called back to the _Beagle_ to continue +his voyage. When they arrived at the mouth of La Plata their most +serious work began. Here there was much tedious charting for Fitzroy, +and Darwin could now leave the vessel for a lengthy trip on shore. +This was doubly welcome. Seasickness was nearly constant with Darwin +while on this entire voyage and every opportunity to work on land was +eagerly seized. This region, too, was rich in objects of interest and +in strange people. While exploring the pampas, beyond Buenos Ayres, +Darwin came across the skeletons of the great mammals some of which +Cuvier had previously described. He studied these bones with much +care, and recognized at once in the megatherium a great similarity in +structure to the sloth he had seen in Brazil. The enormous skeletons +of the glyptodons struck him also as strangely similar to that of the +armadillo. One evening, seated alone in the broad expanse of the +pampas, the idea suddenly swept over him, stimulated, of course, by +his study of Lyell: "Can it be that the little armadillo and the sloth +of to-day are the degenerate descendants of the enormous megatherium +and glyptodon of the past?" But his mind was not yet ready to accept +so bold an idea and he swept it aside. + +The people of this wild neighborhood interested Darwin very greatly, +and he describes them with care. In this connection a charming trait +of Darwin's character comes beautifully in evidence. The absolute +purity of his mind, his utter freedom from grossness, shows clearly in +his account of the first really semi-civilized people he had ever +seen. + +A little later, while exploring Patagonia, Darwin noticed the +terrace-like formation of that desolate country. A flat near the sea +was succeeded by a rapid rise, then came another flat. Three of these +terraces in succession stretch back toward the Andes. At the base of +the high terraces Darwin found marine shells, largely similar to those +of the ocean beach so many miles to the east. His study of Lyell led +him to suspect at once that this portion of South America had been +raised in successive stages out of the bed of the Pacific. When they +passed around Cape Horn and up the western coast he hunted for +similar beach marks on the sheer western face of the Andes, and found +them without difficulty, confirming his idea of the recent rise of +this end of the Andean chain. + +The _Beagle_ continued its voyage up the western coast of South +America until it reached Peru. Once more the abundance of tropical +life is under Darwin's eyes, but now it is the life of an entirely +different section. The dry climate of Peru furnished him with an +environment distinctly unlike that of the moist Brazilian forest. He +collects now with avidity, gathering especially insects and birds. +Then the ship turned its prow westward across the Pacific, only to +stop five hundred miles out at the Galapagos Islands. This little +group he studied intensely, collecting large numbers of insects and +birds. He had not worked over his collection long before he realized +that each island in the group had peculiarities which marked its +animals from those of any other island. Whenever two islands were +close together in the group the differences in their fauna were found +to be comparatively slight. If, however, he examined the animals from +two islands lying at opposite ends of the group, the differences were +always considerably greater. There was, however, a strong general +resemblance among them all and a distant though not so strong +resemblance to the corresponding animals of the Peruvian coast. On +leaving the Galapagos group, Charles Darwin writes in his diary the +suggestive observation that this little group of rocky islands seems +to be one of the greatest centers of creative activity. It was this +interesting resemblance of the animals of these islands to each other +and to those of the Peruvian coast that finally persuaded Darwin that +they were all related and were all descended from those of Peru. For +the rest of his life, with an intensity which increased with each +year, Darwin persisted in a patient search for the possible agencies +by which such change could have been brought about. The problem, +however, was temporarily eclipsed by a pressing geological question +aroused by his visit to the Keeling Atoll. Here his investigation of +coral reef formation absolutely captivated him. In the case of most +coral islands in the Pacific Ocean the reef exists as a circle of +coral enclosing a lagoon of water. In the center of this lagoon stands +commonly a rocky island. It is plain that this is the foundation on +which the coral built. But, in the case of the Atoll, the coral ring +was present and so was the internal lagoon, but there was no rocky +island. The key to the solution came with an interesting discovery. +Darwin began to put down a grappling iron on the outer side of the +reef and to drag up coral. The farther away from the reef he went the +deeper was the water from whose bottom he pulled the coral. What at +first puzzled him was the fact that so long as he dragged up his coral +from depths of a hundred feet or less the coral was alive. Whenever he +went to depths of much more than a hundred feet, his coral was always +dead, though he was evidently pulling it from situations in which it +had grown. Then Darwin remembered the rising Andes, lifting themselves +out of the bed of the Pacific. Here was the correlated movement. The +bottom of the ocean here was sinking. As it sank it dragged down the +corals with it. But the descent was so slow that new corals could +build on top of the others fast enough to keep the reef up to the +surface of the water. At the rate of growth of coral, this would seem +to mean that the bottom could be sinking at a rate of only a few feet +a century. But while the reef could keep up to the surface, the rocky +island must slowly sink. Darwin inferred that there must be a rocky +summit within the lagoon, below the surface of the water. A little +sounding soon discovered this island, and the verification of Darwin's +theory of coral reef formation was at hand. The description of this +Atoll and of his theory of its formation won for Darwin the esteem of +geologists when he later presented it in book form. + +The voyage was continued around the Cape of Good Hope. Pursuing the +usual course of sailing vessels, the _Beagle_ touched once more at +Brazil, returning home to England in 1836, after an absence of five +years. Charles Darwin himself believed this trip to have been both his +education and his opportunity. He had started on it a rather careless +and indifferent student. He returned from it the most painstaking and +patient naturalist the world has ever known. His father, who had +hardly consented to his going because he believed him not stable +enough to be intrusted to his own devices for so long a period, was +profoundly moved at the sight of him on his return. Believing in +phrenology, as did many of the physicians of his time, his father +turned to his mother and said, "Look at the shape of his head; it is +quite altered"; which, translated into the language of to-day, would +read, "How wonderfully the young man has developed." + +A part of Charles Darwin's duty to the British Government was to write +a narrative of the voyage, and this account of his trip upon the +_Beagle_ is one of the great classics of travel in the English +language. It won the confidence and respect of a wide circle of +readers. In his next book he published his observations made at the +Keeling Atoll and announced his theory of the formation of coral +islands. This was a distinctly scientific investigation, and it won +such immediate favor among geologists as to increase materially the +young man's reputation. No one man is ever widely enough acquainted +with the animal world to classify all the specimens gathered on such +an expedition. In accordance with custom, Darwin began distributing +his collections among specialists. Each of these was to identify and +describe, to name, if necessary, the kind of material he knew best. +Among others, Darwin had a considerable collection of barnacles +gathered from boats and wharves in all parts of the world. As he could +find no one sufficiently acquainted with these creatures to classify +them he decided reluctantly to work them up himself. For about eight +years much of his spare time was given to this painfully exacting +work. He expresses himself as fearing it was a waste of time. Few +systematic workers will agree with him. He did his work so well that +it has been unnecessary for anyone to do it again. In addition it +gained him the esteem of a new circle of scientists and that a +decidedly exclusive circle. + +The publication of these books did much for Darwin. His narrative of +the voyage gained the good will of cultured England in general. The +book on coral reefs won the geologists. His "Manual of the +Cirrhipedia" (as the barnacle book was called) secured the attention +of systematic zooelogists. The time was not far distant when he would +need every aid possible toward gaining and keeping the regard of men; +for he was to promulgate a theory that would arouse the bitterest +opposition and the keenest scorn. + +All the while Darwin was working on these books his mind was quietly +busying itself with what he called the species question. The more he +studied the material collected on his long tour, the more confident he +became that the animals of the present are the altered descendants of +the animals of the past. He tried patiently to work out every +conceivable hypothesis to see whether he could account for the +alteration. He felt quite sure animals changed, but how they changed, +and why, he could not for a long time conceive. He knew that gardeners +were constantly producing new varieties of plants, and that animals of +various breeds were clearly the descendants of other and familiar +varieties. Accordingly he began to study the methods of animal and +plant breeders, to visit their farms, to open correspondence with them +and read all their trade journals, to undertake experiments in the +breeding of plants. The longer he worked the more confident he became +of the reality of the change; but for a long time no glimmer of the +cause by which it could be brought about came to his mind. In 1838 he +came across a book by Malthus called "An Essay on Population," in +which the author shows that, whereas man increases by a geometric +ratio, he cannot hope to increase his food supply in more than an +arithmetic ratio. That is, while the food might increase like the +series 2-4-6-8-10, the population would increase like the series +2-4-8-16-32. On this basis it is only a question of time when the +earth will be too full of people for it to be possible for the food to +sustain them. Malthus added many observations and suggestions, but +this is as much of the book as interests us in this connection. Here +was the idea that suggested to Darwin his agency for producing the +change of the animals of the past into those of the present. + +The number of animals of any particular species remains practically +the same. There may be a few more one year, and a few less another, +but on the average, year by year, the number of toads, the number of +blacksnakes, the number of field mice, remains sensibly the same. +Sometimes the rise of man brings an end to the wild population, and so +in the past animals have dropped out of the race. Yet in the long run +and for a considerable time the number of any species is constant. But +each animal produces offspring in quantities sufficient to far more +than replace himself as he dies out. In other words, animals increase +not by addition but by multiplication. Too many are born for all of +them to live. What becomes of the great mass of them? The answer is +they die; most of them die young. Only a few fortunate individuals, +favored by being a little stronger, a little more cunning, a little +more attractively colored than their mates, survive to carry on the +race. + +The skillful gardener, looking over his flowers, finds a plant of more +than ordinary beauty and thrift of growth. When it comes to maturity +he keeps its seeds separate from those of the rest and next year +plants them by themselves. As they come up he weeds out all unthrifty +plants, only allowing the strongest to come to maturity. As they break +into bloom he plucks away all whose flowers do not come up to the high +standard he has set for himself. After a while he has but a few plants +left, but these are the thriftiest and bear the most beautiful +flowers. Again he allows these to mature and selects the seed of the +very finest. Next year the process is repeated. After a few +generations, usually three if the man is skillful enough, he has a +definite strain of flowers that will thereafter come true. This is the +process of artificial selection as carried on by man. + +Darwin saw that Nature is constantly carrying on a similar process. +She produces seeds enough on almost any plant to clothe the world in a +few years if all of them could fall into proper ground and thrive like +their parents. A friend of mine found a mullein stalk that bore more +than seven hundred seed pods and averaged more than nine hundred seeds +to the pod, a total of more than six hundred and thirty thousand +seeds. If each of these could find lodgment on a plot eighteen inches +square, produce a similar number of seeds and plant them all, the +result would be overwhelming. The fourth generation would cover land +and sea, from pole to pole, one hundred layers deep. But there is no +such danger. Year by year the mulleins hold their own and no more. Any +particular field may have more or less, but in the long run the +average for a district is about the same. Some of the seeds are poor +and thin. These scarcely sprout. Others spring up into thin-skinned +plants, and the first frost nips them. Still others lack the woolly +coating in its finest abundance, and the browsing animals eat these. +Others lack power to put out a wide-ranging root supply and the first +drought kills these. Still others fail to send up a vigorous stem and +the passing animal knocks them over and they die. Of the few that are +still surviving, some produce such small and inconspicuous blossoms +that the insects scarcely see them, and they go unfertilized. In the +end only the aristocrats of the group are left, aristocrats in the +best sense of the word. These are strong, thrifty, and beautiful, and +are provided with every defense known to the mullein world. From these +the mulleins of the next generation will spring. Again Nature will +select the best of these, by a repetition of the same process. Thus +year by year the stock is improved. Any new feature that is favorable +helps its possessor to survive, and, if happily mated, will show +itself after a while in the entire group. This, in brief, is the +underlying idea of Natural Selection, as Darwin conceived it. + +In 1842, at Lyell's suggestion, Darwin wrote a short sketch of his +ideas which he, two years later, expanded into a somewhat larger +account. The manuscript of these early views of the theory was +completely lost and has only been recovered within the last few years. +It was recently published under the editorship of Charles Darwin's +son, Francis. It is astonishing to see how clearly the first short +sketch states the underlying conception which all of Darwin's +subsequent work amplifies. Hooker was constantly urging Darwin to +write out his whole theory in the form of a book, and Darwin had begun +to do so in 1856. + +Meanwhile, down in the Moluccas, Alfred Russell Wallace had been lying +sick of a fever contracted during his exploring expedition in that +neighborhood. He had been studying the distribution of the animal life +of the Malay Archipelago. Overcome by sickness, as he lay in bed, he +began to think over a book which he had read not long before, "Malthus +on Population." Wallace had been pondering on the question of the +origin of the animals of the Malay Archipelago. He had not the +faintest knowledge of what Darwin was doing, but was influenced, of +course, like Darwin, by what he read in Malthus. Interesting to +relate, he had come to exactly the same conclusions, writing his +opinions in the form of an essay. By the strangest sort of +coincidence, he sent this essay to Charles Darwin, asking him to read +it, and, if he thought it was not altogether too foolish, to send it +to Lyell for publication by the Linnaean Society. Darwin read with +utter astonishment this essay containing views so absolutely like +those that had come to him from his own long series of observations +and reflections. With uncommon magnanimity his first impulse was to +withhold his own publication entirely, but to this Lyell and Hooker +would not for a moment consent. They were determined that Darwin +should give them his long series of notebooks as evidence of the +independence of his work and that he present to the Linnaean Society, +simultaneously with Wallace's paper, one of his own upon the same +subject. In this manly form both essays were read at the next meeting +of the society. The joint papers provoked instant discussion and +prompt opposition. The world at large scarcely admitted a possible +doubt of the fixity of species. Men generally believed the idea to be +absolutely irreconcilable with their religious faith. Any question of +the fact that the species of to-day exist practically as they had been +handed down to the earth in the beginning by the Creator himself +seemed to most men a direct blow at religion. At this time a very +large number of natural scientists were clergymen, hence the +opposition had abundant and influential support. The storm grew +fiercer and more widespread. The publication in 1859 of Darwin's great +book on "The Origin of Species by Means of Natural Selection or the +Preservation of Favored Races in the Struggle for Life" added fuel to +the flame. + +In 1860 the British Association met in Oxford, and Bishop Wilberforce, +the retiring president, in accordance with the custom of the society, +gave a summary of the advance of science, especially during the +preceding year. Everyone knew perfectly that the bishop would deal +with the species question, and that he would handle it severely. +Darwin was prevented by his usual ill health from being present at +this meeting, but Huxley was there to see that their side of the +question received proper attention. The bishop made a lengthy address, +in the major portion of which he brought forward entirely worthy +objections to Darwin's theories. Toward its close his feelings +overmastered him and he departed from his manuscript and unburdened +his mind. The lack of stenographers in those days and the tenseness +of the moment, which made everyone forget to take down what was said, +make it impossible to tell exactly what happened. It seems that Bishop +Wilberforce, appealing to the prejudices of his audience, said, in +language that now seems ludicrous but then was terribly bitter: +"However, any of us might be willing to consider ourselves descended +from an ape upon his father's side, no one would so demean his +mother's memory as to imagine that she could possibly have shared in +this descent." Huxley, who had waited patiently for the close of the +bishop's address, saw immediately the fatal mistake. Turning to his +companion beside him, he said, "The Lord has delivered the Philistine +into my hands," and, rising, he hurled back at the bishop the +indignant reply, "I should far rather owe my origin to an ape than I +would owe it to a man who would use great gifts to obscure the truth." +The bishop had made the mistake, and the struggle was on. Year by year +it raged. One by one the scientists, first of England, and then of +Germany, took their stand by Darwin. Huxley in England and Haeckel in +Germany were the foremost advocates of the Darwinian idea. Long and +fiercely the battle raged; slowly and gradually men began to see that, +instead of undermining religion, the idea of evolution uplifted +creation and made it not a strange happening in the distant past, but +a divine activity through all time. But the battle had by no means +subsided when one day came the sad news that Darwin's heart, so long +feeble, so serious a hindrance to his work, had beaten its last on +April 19, 1882. + +His own people wished to bury Darwin quietly at his home in Down, but +Darwin now belonged to the nation. A petition signed by many public +men was sent to the Dean of Westminster, asking that his body might be +granted burial in the Abbey. Probably no greater honor can come to man +to-day, and fortunately Dean Bradbury was broad-minded enough to +acquiesce. So it came to pass that the church that had so long +believed him her enemy, that had first so bitterly fought him, came at +length to see that he added a new dignity and worth to her faith, and +took him to her bosom. Darwin's body lies buried in the Abbey. + +In all the glorious company of immortal dead whose earthly frames are +gathered in England's great mausoleum, there is no other one who has +done so much to modify the mind of thinking man. + + + + +CHAPTER III + +THE UNDERLYING IDEA + + +We have seen in the preceding chapters how the idea of evolution +worked its way through the minds of men. Man after man got a glimpse +of the idea, even among the ancient philosophers. But no one could +speak convincingly on the subject before modern times, when a wider +acquaintance with the animal world gave a body of facts on which it +was safe to base conclusions. Even then the idea eluded men, until +there came a worker trained by a long voyage around the world in which +he had nothing to do except to study nature. He finally gathered in +his mind material sufficient to convince himself not only of the truth +of evolution but of the process by which this evolution was brought +about. Every scientific principle is simple in its basal idea. In +actual life the action of the principle may be so bound up with others +as to need a skillful mind for its detection. But under all the +complexities and modifications, like a silver thread woven into a +cloth, runs the basal idea. Until a master has detected it the +presence of it may be unsuspected. But once discovered and expounded, +thereafter anyone may follow out its workings. So it is with the +Darwinian idea of selection. It waited long for a discoverer, but, +once found, we cannot but wonder why men did not see it earlier, it is +so simple. + +Mr. Darwin's mind, while slow and cautious, had a wonderful +perseverance. When he had finished his work he had not only given a +clear account of the process of evolution, but he had foreseen almost +all the valid objections that were afterward to be brought against his +theory. Some of them he had explained quite fully; of others he +indicated a possible explanation; of still other questions he +confessed that as yet they were not plain. But the whole theory is so +simple in its fundamental ideas that it has completely revolutionized +the whole aspect of modern biology and, indeed, of modern thinking in +many lines. + +There are four underlying conceptions, each simple in itself, which +must be clearly perceived before one can understand Mr. Darwin's +theory of "Natural Selection." The first of these is known under the +name of Heredity. It is a matter of common observation that every +animal or plant produces offspring after its own kind. Under no +conditions would we expect a duck to lay an egg from which could hatch +anything but a duck. No Plymouth Rock chicken mated with another of +her own kind will ever lay an egg that will produce a Rhode Island +Red. We may believe that the dog has descended from some form of wolf, +but it is not meant that at any particular time in the past any wolf +mated with a wolf ever produced pups that were anything but wolves. + +Why this should be so is one of the most profound problems of biology. +Nothing but the fact that the process has gone on under our eyes for +so long a time could blind us to its marvelous character. To open the +egg of a chicken and examine it by the most refined methods known to +science is to find in it absolutely nothing that could be by the +widest stretch of the imagination considered anything like a chicken. +The biologist who has examined such eggs before and knows them in all +stages of the process may recognize in an egg which had been incubated +for a short time something which his previous experience tells him +will become a chicken. But it has not the faintest resemblance to a +chicken until later in its development. In early spring one may gather +pond snails from any country stream and place them in an aquarium. The +change from the cold water on the outside to the warmer water of the +aquarium and the temperate climate of the room hastens the process +which in the stream would not take place until later. In a short time +one may find fastened to the glass side of the aquarium the little +mass of transparent jelly which surrounds and protects the delicate +eggs of these creatures. Fastened as they are it is easy to direct a +magnifying glass so as to observe the change which goes on within +these transparent eggs. It is even possible to apply a microscope in +such a way as to watch the transformation under the low power of the +glass. At first the eggs are as clear as water, having at the center a +slightly yellowish spot. This central mass divides and subdivides +until the separated sections grow so small and numerous as to lose +individuality. Then the mass begins to press out here and dent in +there. After a little while a double line of fine, hairlike +projections runs around the creature. These hairs wave in such fashion +as to make the embryo snail revolve slowly in its egg. A little later +and swellings become more pronounced over the surface. One side +flattens; the rotary motion stops; eyes appear at the front of the +animal; a hump on the back begins to be covered with a shell, and the +little creatures, pushing from the jelly, start their life journey on +the side of the aquarium. Why did it happen? How did it happen? Here +we have seen creation at work. Here surely the hand of the Creator is +working in the only sense in which the Creator may be properly said to +have a hand. How the history of the substance out of which the egg was +produced provides for the future development of that egg no man has +yet clearly said. This is not to say that we shall never know, still +less is it to say that this can never be known. Ralph Waldo Emerson +has said that there is no question propounded by the order of nature +which the order of nature will not at some time solve. If he is right, +and I believe he is, we shall at some time know how it is that this +egg produces this snail. But, as I said before, nothing but the +frequency with which the process goes on under our eyes could possibly +blind us to the marvel of it. + +The regularity with which each animal reproduces its kind is no more +surprising than the faithfulness of that reproduction. Some of our +birds have wonderful markings on their plumage. It is astonishing to +see with what fidelity the feather of a bird may reproduce the +corresponding feather of its parent. It will occur to everyone how, in +the human family to which he belongs, there is some little peculiarity +which, while not appearing in every member of the family, when it does +appear is remarkably uniform. It may be only the droop of an eyelid, +it may be a tendency to lift one side of the lip more than the other, +it may be the peculiar shape of a certain tooth in the set, and yet +when it appears it comes with astonishing similarity in all who +possess it. So much for the principle of Heredity. + +The second great underlying idea is known by the name of Variation. We +have just been dwelling on the regularity with which parents produce +offspring like themselves. We must now draw attention to the fact +that, while it is true animals must absolutely belong to the same +genus or species, even to the same variety, none the less no animal is +exactly like his parents. Furthermore, in a group of animals produced +at the same time from the same parent each one will have at least some +small point in which he differs from every other one in the group. Two +animals may look alike at first to the undiscerning eye, but a keen +analysis of the measurements of the various parts of their bodies will +show distinct differences. This is quite as true among lower animals. +A toad may lay a double string of four hundred eggs which may be +fertilized by the same male at the same time. These eggs may develop +into tadpoles in the same pool not over a foot square. Within a few +weeks these little toads may have gained their legs, lost their tails, +and all may have left the water and taken to the ground upon the same +day. Already the careful observer will notice differences among them. +Some are larger than others, having grown more rapidly even though +their surroundings were exactly the same; others are more skillful in +their peculiar method of throwing the tongue at an insect they wish to +catch. Still others will be differently colored. They might be +arranged to show a considerable gradation between the lightest and the +darkest of the group, though there may not be anywhere in the row a +considerable gap. It is variation in animals of the same parentage and +same surroundings which in the mind of Mr. Darwin made evolution +possible. He always favored the idea that it was the continuous +accumulation of these small variations that finally produced the +profound changes which mark the new species. He admitted the +possibility of the occasional appearance of those more distinct leaps +in variation on which the present school of mutationists so strongly +insists; but he believed them to be less influential, in the general +trend of evolution, than the slower but much more frequent variations. + +One of the most complicated and perplexing problems in the biology of +to-day is the question of the origin of these variations. It is quite +as hard to understand as is the method by which animals produce their +own kind. No problem is being more earnestly studied. Suppositions we +have in considerable number, and two of these at least may reasonably +be mentioned. We will consider first the less certain theory. There is +nothing in the egg that in the remotest degree resembles its parent. +The old idea that every acorn had in it a miniature oak which only +needed to unfold itself, or that the hen's egg had within it a +miniature chick which only needed the warming process in order to make +it evident, could not possibly survive the invention of the +microscope. We may not, and we certainly do not, know everything that +is in one of these eggs, but we do know most certainly that what is +there has no resemblance to what it will be in time. The biologist +finds in the nucleus or central core of every growing and reproducing +cell certain minute bodies which Weissmann believes do much to +determine the growth of the rest of the cell. He believes also that +there are many more such "determinants" than are necessary for the +reproduction of the cell. Each of these determinants may be fitted to +produce slightly different results, but what decides which of them +shall have its own way is quite uncertain. It may be that one +determinant happens to be more favorably placed than others in the +cell and that it has consequently secured more of the nourishment that +comes to the cell in the blood of its parent. If this is true it would +certainly be favored in the competition. We are becoming quite certain +that whatever variations arise really start in the egg. The simplest +conception as to the cause of variation would seem to be varied +experience. One man trains his brain, another his hand; and in each +case the organ so trained develops. But science is strongly of the +mind that such influence does not reach the next generation. + +A musician may have taught his fingers to be nimble; may have given +them speed of motion and precision in their action. No child of his +born after he acquired this wonderful facility of execution is any +more likely to be a skilled musician than a child born before he had +ever practiced enough to be anything more than a crude performer. +Science is nearly certain that his children are just as likely to be +talented along musical lines if he himself never had become a +musician, simply because he had it in him to be a musician. In other +words, they may inherit the talent which he developed, but they +inherited it not because he developed it, but because it was in him to +be developed. This is in accordance with the famous principle that +there is no inheritance of acquired characters. We shall touch this +question a little more fully in a later chapter, in speaking of the +development of the evolution theory since Darwin's time. + +If we are right in this matter, and we certainly are nearly right, +variation must take place for the most part in the germ. These +variations may not show until the animal has grown up, but they must +have taken place among the determinants in the germ cell or they would +not reappear in subsequent generations. + +There is another process by which new variations may arise and which +is more easily understood. It is the method of double parentage. The +Barred Plymouth Rock chicken had its origin in such a double ancestry. +The one parent was a Black Java whose color has disappeared entirely +in the cross, but whose single comb with its few large points comes +out clearly in the newly produced fowl. The other parent was a Barred +Dominique. It is to this parent that the Plymouth Rock owes the +interesting cross markings on its feathers. The comb on the head of +the Barred Dominique is of the type known as the rose-comb, having +many rows of slight projections. This has completely disappeared from +the Plymouth Rock fowls. I am told that the skilled chicken fancier +can tell, concerning many points in this fowl, to which of the crossed +ancestors each quality is due. To a certain extent it is undoubtedly +true that here we have the secret of the origin of many of those +interesting people whom we are pleased to call geniuses. They may not +possess any qualities not clearly discernible in various of their near +ancestors, but in them we find what we, for the lack of a better +understanding, call chance combination in one individual of the finer +qualities of many ancestors, and this individual is so placed in life +as to have these qualities developed and strengthened. + +Charles Darwin, humanly speaking, may be accounted for as the happy +combination of a double heredity and a favorable environment. He +inherited the scientific inclinations of his grandfather, Erasmus +Darwin, and the patient, sturdy honesty of his other grandfather, +Josiah Wedgwood. These developed under the stimulus of the long +five-year voyage, face to face with the world of nature. This happy +complex produced the master biologist. To believe that he came about +purely by chance requires a great stretch of the imagination. "There's +a divinity that shapes our ends." + +We have endeavored to make clear two of the basal ideas underlying +evolution. One of these is responsible for the continued production of +animals or plants of the same kind, preventing the world from becoming +a wild kaleidoscopic and fantastic dream. Heredity is the conservative +force of nature. The other idea underlies the development of new +departures which keep the world from being a dull, dead, unending +repetition of the same monotonous material. Variation is the +progressive tendency in nature. + +The third basal idea is that of Multiplication. Animals and plants +multiply; they do not simply increase, they increase in a geometrical +ratio. Anyone who has worked out one of these geometrical ratios knows +how wondrously they mount up. There is an old familiar story of the +blacksmith who asked the price at which the stranger would sell the +horse he was shoeing. The owner of the horse replied that, if the +blacksmith would give him one penny for the first nail he drove into +the shoe, two for the second, four for the third, and so on, he might +have the horse. No hundred horses in the world taken together have +ever brought such a price as the blacksmith would have had to pay for +the animal on which he was working. This is no circumstance to the +awful story of what would happen to the earth if any animal could +multiply unrestricted. The usual number of eggs laid by a mother robin +for a single brood is four, and she may produce two broods in one +season. This would mean that the original pair had produced eight +offspring, four times their own number. If we can imagine these mating +the next year and producing their kind in the same proportion; and, if +we further suppose that each robin needs a space one hundred feet +square from which to gather his food, we realize the astonishing fact +that in fifteen years every patch one hundred feet square in +Pennsylvania and New York would each have its resident robin, while +the following season would find a robin on every similar patch from +Maine to the Carolinas. Of course this could never happen, this is +simply what would happen if all the robins could grow to maturity and +reproduce at the normal ratio. But the robin is a comparatively slow +producer. + +Our turtles are more prolific. Twenty eggs would probably not be an +unusual number. If we could imagine a turtle to live in the sea and to +produce at this rate; and, if each turtle should need as much room +each way as the robin, and a depth of water equal to its width, before +the robins had spread over New York and Pennsylvania the turtles would +have filled all the seas of the globe. Frogs are even more remarkable +in this respect. Two hundred eggs is not an uncommon number. If each +frog required a space twenty-five feet square on which to subsist, the +entire earth would be more than covered with them within six years. It +is ludicrous to think of such numbers, especially when we realize the +hundreds of thousands of kinds of animals there are in the world, each +of which is also multiplying, and it becomes evident at once that only +an infinitely small proportion of all these creatures can possibly +survive. This, then, is multiplication. + +Here comes into play the fourth basal idea in Mr. Darwin's +explanation. This is the part of Selection. When man produces new +varieties of animals he does it by picking out from his flocks or his +herds such as conform most nearly to his idea of what is desirable. +These he mates, and from their progeny he selects the ones that suit +him best. Generation by generation he gets his domesticated animals to +conform more nearly to the standard of his desires. Natural selection +works in exactly similar fashion. Of all the eggs that are produced by +the animals at large in nature an overwhelming proportion never +develop at all. They dry up, are eaten by their enemies, find no +suitable place or time for development and decay, or are overtaken by +some other calamity. Of the animals which emerge from the remainder an +overwhelming majority come to an untimely end within the first few +days of life. Each has countless enemies which prey upon him, and +these have scarcely devoured him before they themselves become the +prey of some stronger creature. Until Mr. Darwin gave us his elemental +idea it was taken for granted that it was a matter of pure accident +which survived and which yielded in the struggle and cares of life. It +was Darwin who showed us that in this tremendous struggle against +those of his own kind in the search for the same food, against the +elements, in securing a mate, any animals possessing a superiority, +however slight, must have some little advantage in the battle. +Certainly, where so many must utterly fail, only those could possibly +succeed who were well fitted to the circumstances in which they must +live. We used to think animals were destroyed by the "accidents" of +life and no one could foretell accidents. Mr. Darwin made clear that +it was not a question of chance. That which might happen to any +individual animal might be what we, not knowing the process, called +accident, and yet there could be no possible doubt that those who +succeeded were better fitted to battle with life than those who +failed, and that their success was due primarily to their being thus +advantaged. Consequently, if generation by generation the so-called +accidents of life are constantly eliminating the unfit in overwhelming +proportions, not only must the positively unfit disappear, but even +the less fit. The more keen the struggle, the fewer could survive and +the fitter they must be to survive at all. This is Selection. These, +then, are Darwin's four great factors of evolution: Heredity, +Variation, Multiplication, Selection. + +From these it results that the animals and plants naturally become +better adapted to the situation in which they are placed. When, as is +constantly happening through the history of the earth, a change occurs +in the physical geography of any region, when a plain is lifted to be +a plateau, or a mountain chain is submerged until it becomes a row of +small islands, this alteration will produce uncommon hardships among +animals, even though they were well fitted to the old conditions. Any +animal or any species of animals which meets such a calamity has +before it only three possible outcomes of the struggle. First it may +be plastic enough and it may vary enough in the right direction to +adjust itself to the changed conditions. In this case it and a favored +few like it will occupy the altered territory. The second possibility +is that it may migrate while the actual change is going on, thus +remaining in the sort of situation suited to it and its kind. The +third possibility is the one which overtakes a great majority of +animals--they die. Even the entire line dies out, and the strata of +the rocks are filled with the bones, shells, and teeth of such as have +met this fate. They have become extinct. + +Thus far in this chapter we have been considering the influences under +which it is conceivable that animals should advance. There is no +question whatever that there are too many animals born, nor is there +any possible question that a very large proportion of them must +certainly die. There is equally no doubt that every animal produces +after its own kind, and that its offspring, while they resemble it +closely, still vary a little from it and from each other. This fact is +perfectly plain to the most superficial observer who thinks on the +matter at all. It is not so plain, nor is it easily demonstrated, that +all of these acting together do surely, even if slowly, alter the form +and behavior of the animal world. It is difficult to prove that there +is going on under our eyes a steady and real improvement in the +adaptation of the animals and plants around us to the situation in +which they are placed. As far back as man's memory runs they seem to +have been about what they now are; as far even as man's historical +record runs they seem to have suffered no great alteration. The +Egyptian of the old tombs is much like the Egyptian of the same rank +to-day. The African of the tombs has the African features of to-day. +Under such circumstances it is hard to prove that there is a steady +and undoubted advance. For the most part the balance of the animal +world is fairly even, and any species does not ordinarily change +rapidly enough or migrate widely enough to show us its new features. +It is difficult to see the struggle which we are so sure is going on. +The life of animals is so hidden in many of its details that their +joys and sorrows, if such we may call them, scarcely fall under our +observation. Now and then an opportunity comes to see the process of +adaptation work itself out. The struggle for existence begins anew and +is carried on with special vigor, with victory, temporary or +permanent, to one of the participants in the struggle. + +The opportunity to observe such a change is presented in the United +States by the introduction of the so-called English sparrow. This +little creature, received at first with such joy, soon became the +object of an almost bitter hatred on the part of very many people. +This is really due to the fact that this bird is one of nature's +darlings and thoroughly succeeds where it has an even chance. + +The number of birds of any particular species which a region will +support seems to be fairly definite. If a species is especially +protected until it becomes unusually abundant, the removal of the +protection commonly brings it down promptly to its original numbers. +On the other hand, an accident of severe character or a special +persecution may much diminish the number of the species, and still it +will, within a comparatively few years, return to its previous +abundance. + +The inhabitants of Florida who own orange groves will never forget the +winter of '94-5. A bitter cold wave swept along the coast and killed +such large numbers of orange trees as almost to cut Florida out of the +orange market and to open the gate to California, who was eagerly +offering her fruit. This same frost caught the migrating blue birds +and killed them by the thousands. When spring came bird-lovers +throughout the eastern United States found an astonishing scarcity of +these favorites. It was feared that with numbers so small they could +not possibly compete with their enemies and with whatever untoward +circumstances should be their lot. But there is room in this +environment for a definite number of bluebirds. When this number was +suddenly reduced the chances to make a bluebird's living were so +wondrously multiplied that young bluebirds had such an opportunity in +life as their fellows had not had for many long years. Accordingly +they thrived as never before, and, of their progeny, a larger +proportion lived to the following year. It was only a few years before +the number of bluebirds had risen. Now we probably have as many as we +have had for a long time past. I cite this simply to show that a +region can support a certain number of animals of any one particular +kind, and that the animal is likely to multiply, if given a fair +chance, until it has reached such proportions. Now to my story of the +rapid development of a newcomer. + +In the year 1850 a resident of Brooklyn came home from a trip to +Europe. He was a lover of birds, and while in Europe had been +particularly attracted, no one now knows quite why, to the common +House Sparrow, as it should be called. It is no more abundant in +England than in many parts of the continent of Europe. A name that has +been used for a long time is very hard to cast aside, and we shall +probably continue to mistakenly call him the English Sparrow to the +end. Our Brooklyn traveler brought home with him from Europe eight of +these interesting little birds and succeeded in inducing his +colleagues in a scientific society to share his interest in them. Not +wishing to commit the newcomers suddenly to the rigors of the American +winter, these men built a large cage for the sparrows, meaning to set +them free in the spring. For some reason or other when the winter was +over the birds were all dead, and this first attempt to introduce the +sparrow into America failed entirely. The little bird had won so many +friends that his success was now sure. Finding a favorable +opportunity, these Brooklyn men dispatched an order to a man in +Europe, asking him to supply them with one hundred English sparrows. +The consignment came in good shape and the birds were liberated on the +edge of Brooklyn. This was the first of a number of introductions. A +little later New York City sent for two hundred and twenty of these +interesting creatures and turned them loose in her parks, while +Rochester, with what was then considered great public spirit, +purchased one hundred for herself. But the most progressive city in +this respect was Philadelphia. She had long been troubled with the +spanworm on her trees. This detestable larva had the unpleasant +fashion of lowering itself by a long silken thread from the shade +trees then so abundant in that beautiful city. The spanworms traveling +around over the clothing of the passersby were so objectionable to +everybody that it was with greatest delight that Philadelphia heard +of the new birds which ate the pest. One wonders why some +ornithologist did not look at the bird long enough to see that it had +the sort of a bill characteristic of birds that eat seeds. It is true +that most birds feed their young on insects, hence there is a time +when any bird is apt to be insectivorous. But the structure of the +sparrow's bill, like that of all finches, should have warned these +bird-lovers that the sparrow was not to be depended upon to earn his +living by catching worms. It is easy, however, to be wise after the +event. Philadelphia believed she was engaging in a particularly +advanced movement when she imported from England one thousand English +sparrows, nearly as many as were liberated by all other cities +together. These birds were turned loose among the shady streets and +wide spreading parks of the City of Brotherly Love. + +It is a serious matter lightly to disturb the balance of nature by the +introduction of a new species. It is true that the sparrow did eat +some spanworms and for a while enthusiastic bird-lovers hoped that +here was the solution of the difficulty. Philadelphians will also +remember that, with the spanworm removed from competition, the tussock +moth, whose caterpillar carries on his back a series of yellow, red, +and black paint brushes, at once become the permanent parasite of the +long-suffering shade trees. This caterpillar is covered with bristling +hairs, very closely set. Almost any bird objects to hair in his +victuals; and this particular larva has hair more than ordinarily +objectionable, for it irritates wherever it pricks the sensitive skin. +This coating seems to protect the caterpillar from the sparrow, with +the result that Philadelphia's trees were soon nearly defoliated by +this comparatively new pest, worse than the spanworm. With the paving +of the city's highways and the consequent shutting off of the air from +the roots, the trees have largely disappeared from the streets of +Philadelphia. With them have gone a fair portion of the tussock worms, +but the sparrow holds his own. Here is a new bird in the field, and +the struggle for existence on the part of every other kind of bird is +now more complicated and severe. The sparrow can live where the rest +of the birds have no possible chance. He throve so well in this +country that by 1875 he had spread over five hundred square miles in +the neighborhood of our larger Eastern cities. Thus far almost +everybody was pleased with the new introduction. Within the next five +years he had spread over more than fifteen thousand square miles, and +wise men were beginning to feel doubtful of the virtues of their +aforetime friend. When by 1885 more than five hundred thousand square +miles had been occupied by the enterprising little fellow, there +remained no longer a doubt in the minds of most people that the +sparrow was an unmitigated nuisance and great fears were entertained +that he had multiplied to such an extent as to be a serious menace. +Here, then, is a modern instance under our own eyes of a victory in +the struggle. If the sparrow has multiplied rapidly, while all the +other birds have either only held their own or even have diminished in +numbers, it is quite evident he must be better fitted to the +conditions than they are. What are his fit points? Why does he succeed +while others fail? The thoughtful bird-lover will have little trouble +in understanding at least some of his victory-winning characteristics. +How did he come to be almost the only bird who can live in large +numbers in our great cities, without losing his ability to get along +in less crowded situations? + +In the first place this interesting bird is a clannish fellow. He has +lost the ordinary sparrow habit and has come to like to live in +crowded groups. Seclusion is not at all to his taste, and if there are +only a few sparrows in the neighborhood those few will most certainly +be found living near each other. One of the early adaptations of the +sparrow to his city surroundings was the ability to find for himself a +considerable proportion of his food in the undigested seed that could +be picked up from the droppings of the horses. This naturally led the +surplus sparrows out through the many thoroughfares leading from any +large city. Where horses went sparrows could follow. Accordingly along +the great lines of travel this bird found the simple path by which he +could enter new territory. Meanwhile box-cars came into our large +cities with freight. Sometimes they had carried grain, sometimes +cattle. In either case it was not unlikely that a certain amount of +grain should be found scattered over the floor of such cars. The +sparrow visited these cars for the grain, and it must have been no +infrequent accident that a door should be shut upon a group of +sparrows, especially in inclement weather, when they were apt to be +huddled in a dark corner of the car. These prisoners would be carried +to the destination of the car and there liberated, thus producing a +new center of what we are now inclined to call infestation. By such +means the English sparrow has spread over much the larger portion of +the American continent. Few birds are bold enough to visit a railroad +car. Of the few who might be tempted, most are timid enough to fly on +the first approach of man. Hence they fail to gain this chance of +spreading. They must remain in the old crowded home. Meanwhile the +sparrow, thus transported, finds a new home with fewer or no sparrows. +The struggle is less keen. More of his kind can live. His boldness +has been here a fit quality and has helped him in the race. + +Man is only slowly coming to be a city-dwelling animal. Although it is +a voluntary process with him, he still usually visits the country with +much enjoyment. He has not as yet learned to adapt himself thoroughly +to the city, for somehow city life kills him. Families that move into +the city gradually have a smaller number of children in each +generation until shortly the family is wiped out. The population of +the city must constantly be replenished from the country. But the +English sparrow is more adaptable than are the people. He has made +himself at home in the heart of the biggest city. The Wall Street +canyon is not deep enough, nor contracted enough, nor free enough of +food to blot out the life of the English sparrow. At the heart of the +deepest gully among the skyscrapers of our biggest cities we find this +little bird hopping between the horses' feet, darting out from under +the wheel of the push-cart, fluttering only a few yards to a place of +safety, to return at once to his scanty meal upon the pavement as soon +as opportunity offers. He is a typical city dweller and has learned to +thrive there. Again in this matter he has distanced other birds to +whom the city is more deadly than it is to people. + +Another very important element in his fitness for the struggle of +life lies in the fact that he is unafraid of man. He is wary of man; +by which I mean he will quickly fly up from in front of man's feet. It +is exceedingly difficult to catch a sparrow in one's hand. It is far +easier to lure a pigeon within reach. But the sparrow, when escaping +your hands, comes to rest but a slight distance away, only to elude +you quite as successfully if you try again. If the sparrow is let +severely alone he becomes more and more familiar with men, flies less +promptly, and goes a shorter distance, but any attempt to trap him +renders him shy more quickly than almost any other bird we have. He +soon learns to avoid a trap in which his companions have come to +grief. Those who would poison or trap sparrows must change constantly +the base of their operations. This fearlessness of man is a valuable +asset to the bird, for it is an important defense against other foes. + +The most serious enemy the birds at large have, after man himself, is +the bird of prey. Hawks and owls capture a large quantity of our +smaller birds. Now the hawks and owls are for the most part shy of +man. They have gotten a bad reputation, especially if they are of any +size, because of their more or less pronounced proclivities for +seizing our domestic poultry, and consequently many people will fire +upon a hawk or an owl who would probably fire upon no other bird. By +living close to man the sparrow is largely saved from the danger of +capture by these carnivorous creatures, and this is the first and a +very important element of the advantage to the sparrow of living near +man. But there is the additional advantage that man scatters about +him, in one way or another, a very considerable amount of waste food. +I have suggested that the seeds in the droppings of the horse form a +large proportion of the sparrow's food, and horses are to be found +only with men. In the neighborhood of man's home, unless he has become +sanitary to a degree which has only been attained in recent years, +there is usually more or less garbage, kitchen offal of one sort or +another. To this the sparrow has easy access and from it he makes many +a meal. But this fearlessness of man gives him still another advantage +which his competitors fear to use, it provides him with nesting sites. + +Man has the faculty of putting up ornamental trimmings on his house, +and there is no spot the sparrow chooses more willingly in which to +build his nest than the ornamental quirks and cornices of man's +architecture. A Corinthian column with comely leaves in its capital +seems especially designed for the comfort of the sparrow, and his +distinctly untidy nest is the familiar disfigurement of almost every +ornate public building. These are the advantages which come to the +sparrow from his willingness to associate with man, and there are +comparatively few birds with whom he must share them. Few birds select +the immediate neighborhood of man's home for their nests. They may +live in the neighboring trees, they may haunt his orchard, but his +house, for the most part, they decline to frequent. + +Still another quality which makes for success in this buccaneer is the +willingness with which he will vary his food as occasion requires. It +is a not infrequent characteristic of the bird family that each +species should have its own rather restricted diet. Birds are quite +particular eaters, and many of them will come well nigh to starvation +before they will use unaccustomed food. The sparrow, on the contrary, +like man, eats almost anything he comes across that could reasonably +be considered edible. He belongs to a group of birds which are +structurally adapted to cracking the hard coats of seeds. This group +of birds known as the finches is provided with the sort of bill +familiar in the ordinary canary bird. It is short, heavy at the base, +comes quickly to a point, and is firm and strong. With it the bird +readily breaks through the hard outer coat of most seeds and feeds +upon the rich cotyledons that are enclosed within. Nowhere in its +entire structure does the plant crowd so much nourishment in so little +space as it does in the seeds. It is not by chance that the great +human food is grain. The sparrow belongs to the one bird group that +makes a specialty of such seeds. + +Most of the English sparrow's cousins in this finch group confine +themselves rather rigidly to this diet. Here the variability of the +sparrow again gives him the advantage. He may have the family fondness +for seeds, but in their absence he can be content with almost anything +edible. In the early springtime, when the seeds of last year are gone +and those of the new year have not yet been produced, the sparrow is +not averse to eating young buds from the trees. At this time he is not +unlikely to eat our sprouting lettuce and peas. It is easy to be +severe on him in this matter; but for a creature like man, who has the +same tastes, who eats the enormous buds of the cabbage, the +cauliflower, and the brussels sprouts, or the more tender buds which +he calls heads of lettuce, it seems particularly inappropriate that he +should throw stones at this little creature whose tastes are so +similar to his own. + +While seeds are more suitable for an elder bird they are altogether +too indigestible to be the food of nestlings. So when the sparrow +finds its nest full we know he must sally forth in search of +nourishment more simple of digestion. Now for a few weeks he searches +assiduously, catching insects and caterpillars of various kinds, and +feeds them to his young. This taste passes as his children grow older, +especially as shortly the seeds begin to ripen. Now is the time for +the sparrow to fatten. Now he is eating the food for which he was +really built. By the time the wheat is ripe there are sparrows enough +about to form quite a flock, and when these settle down in a wheat, +rye, or oats field and feed upon the grain, meanwhile shaking out upon +the ground perhaps as much as they eat, the farmer begins to realize +that the sparrow is not his friend. + +When winter comes the struggle for existence among the birds is +intensified, and comparatively few of them dare face it. Most of our +birds betake themselves to less rigorous quarters, leaving to the +sparrow a comparatively small number of competitors for the diminished +supply of food. As long as the snow is off the ground the sparrows can +find sufficient sustenance. They gather themselves into groups and +sally out from the city into the open country. The immediate result is +that great quantities of weed seeds are seized upon by the English +sparrow, as, indeed, by every other finch which is with us in winter. +Perhaps we have not given the little fellow credit for the good he +does at this particular time, for the rest of the account truly does +not help him in our esteem. + +There is a further direct advantage in the sparrow's sociability. One +robin may nest in the vines about your porch. If there were room for a +dozen, scarcely more than one would be likely to use it, because he +would drive away any other robin who attempted to share the +neighborhood with him. To the sparrow company is always in order. +While he may quarrel from morning until night with his fellow, it is a +sociable quarrel and neither would willingly forgo it. This union is +strength among birds, as with man. Every animal is safer from his +enemies when he can have the constant presence of others of his own +kind. The deer that stays in the herd is safer from the wolves. It is +only when the latter succeed in cutting out some weaker or less +sagacious animal that these carnivorous creatures succeed in tearing +down their prey. I think the superiority of the sparrow over most of +our common birds, when considered as a city dweller, is scarcely +understood. Because he had won in the race with other birds is no +necessary indication that he warred directly against them. Bird-men +often attribute to him a quarrelsome disposition, as if he actually +drove other birds away. It almost seems like animosity against the +sparrow to speak of him as attacking blackbirds and crows. It is a +cowardly crow who can be driven away by a sparrow, and if the two +cannot live together it seems to me certainly to the discredit of the +crow and not of the sparrow. I believe the truth to be that, while +the sparrow is undoubtedly a quarrelsome fellow, his bickerings are +his form of social converse with those of his own kind. A quarrel +among themselves seems not to indicate animosity, but would appear to +be the sparrow's idea of conviviality. It rarely leads to serious +results. I have never seen a male sparrow trounce any other bird with +half the vigor that I have occasionally seen the mother sparrow evince +when she caught her male companion by the feathers of his head, hung +him over the side of the limb, and vigorously and thoroughly shook him +until he desisted from his annoying and possibly insulting attentions. +The truth of the matter is that a colony of these little birds, with +their continual social chatter, including their quarrels, makes such a +continuous noise that the ordinary bird, which is generally of rather +quiet disposition, is too much annoyed by the unending nuisance to +find the neighborhood at all to his taste. Where a large number of +sparrows have gathered together the conditions are such as would give +a robin or a bluebird nervous prostration, and his only recourse is to +depart to a neighborhood where there is more peace and quiet. But our +English sparrow is not only better fitted for the struggle than the +robins and bluebirds, the orioles and the wrens. He has one important +advantage over even his own sparrow cousins. The males are +handsome--much more so than the females or than their sparrow cousins +in general. + +In the song sparrow, field sparrow, chipping sparrow, and the fox +sparrow the male and female are very nearly alike in color. It often +becomes necessary for the bird-man to examine the internal organs of +the bird he is stuffing before he can certainly decide its sex. But +there is no difficulty whatever in telling the male from the female of +the English sparrow. The male is far the more ornate bird. His back is +striped with a richer brown; his head has two splendid dashes of +chestnut over the eyes; his throat and breast are splashed with red +and lustrous black; his bill is a clear fine black. Altogether the +bird is strikingly colored for a sparrow, and this characteristic is +the more remarkable when we see how quiet and somber is his more +modest mate. This brilliancy of male plumage in the presence of the +somber color of his mate would seem to indicate that the English +sparrow is eye-minded rather than ear-minded. It is true among human +beings that most of them are eye-minded. That is to say, they notice +things with their eyes chiefly. Memories they have are memories of +things seen; recollections of their friends bring up the appearance of +their friends. Their language is full of metaphors which imply form +and shape. But occasionally we come across an ear-minded person. He +remembers voices quite as well as he remembers faces. To him music is +an unending delight, and painting and sculpture fall into a distinctly +secondary place. This is ear-mindedness. Now, most of the sparrows +seem to be ear-minded, at least as far as their recognition of their +mates are concerned. In this group beauty of song is developed many +times oftener than is especial ornateness of plumage. The bird-lover +who is himself keen of ear is never tired of listening, when in the +field, for the two low notes with which the vesper sparrow introduces +a song, the rest of which is not at all unlike the one of his +song-sparrow cousin. The field sparrow begins more like the song +sparrow, but ends with an often repeated note, which not a little +resembles in general character the somewhat more monotonous song of +the grasshopper sparrow or of the chippy. In comparison with these +melodious birds the English sparrow makes no showing whatever. His +voice is harsh and querulous, although very occasionally it is +possible for the bird-lover to detect a note or two which would +indicate that, if he were properly educated, his voice might amount to +something. He wins his wife not by his pleasant voice, but by his +attractive appearance and his winning ways. We have every right to +infer from the character of its fellow birds of the sparrow family +that once the female and male sparrow were colored about alike. But +Madam English Sparrow was apparently eye-minded rather than +ear-minded. Whatever pleasant voice a suitor might have seems to have +been to her without attraction, and there was nothing to encourage him +in developing it, nor was she likely to mate with him for it and +transmit it to her male children. On the other hand, let a suitor +appear in whom a more brilliant coloring proclaimed his superior +vigor, and this seems to catch her eye at once. The less accomplished +rival in the tournament of love seems to have been already forgotten. +To their children these successful characteristics were naturally +handed on and led to equal success on their part. If any of these +children possessed this badge of honor in a more than ordinary degree, +he was the more likely to win a mate and thus again the opportunity of +passing on to his offspring his own distinct advantage. Generation by +generation the males have become more beautiful and the females more +discriminating. That the bird is either instinctively or actually +conscious of this advantage would appear from the constant fluffing of +his feathers and spreading of his highly colored wings with which he +evinces his admiration for his ladylove. Even the most hardened +dweller in the city can scarcely have failed to see the sparrow spread +his wings, fluff his feathers, and sink close to the ground, twirling +and gyrating about the object of his affection. It must give him a +shock to see how often she proves temporarily or hypocritically +indifferent to the demonstrative proceedings. Indeed they may +terminate in a thorough trouncing of the male on the part of the lady +of his affections. Now this preference for color over song must have +evidently evolved in connection with the development of social habits +in the English sparrows. His cousins of the fields, our native +sparrows, are much less social, much less likely to be met with in +flocks. To birds who scatter more, beautiful song is a great +advantage. It can be heard at a long distance. But when birds flock +together a much better advantage is that of beautiful clothing, added +to alluring ways. + +But we have not nearly exhausted the catalogue of the traits belonging +to our little friend which give him the advantage over other birds in +the struggle for life. His ability to remain with us in winter when +most birds are gone stands him in good stead. + +It is readily observed by one who pays the least attention to outdoor +life that winter finds us with comparatively few birds. North of +Maryland and the Ohio River the robin is practically absent in the +winter, except in much diminished numbers close to the border. The +bluebird is similarly absent; the great flocks of blackbirds are gone; +the bobolink is missing entirely; the thrush and the catbird have all +left; the flicker and red-headed woodpecker are also spending their +winter in the South. The great mass of our bird population has left us +until warmer weather shall bring back to us once more our feathered +friends. It is true that we are south to the snowbirds or juncos, and +their little slate-colored bodies, with their light breasts and their +white on each side of the tail, make our bare hedge rows brighter by +their presence. A few of our birds like the song sparrow and the +cardinal are hidden away in the thicket, and have not all joined their +comrades in the south. + +The English sparrow was once probably quite as migratory as any of the +rest of these, but a great change has come over his habits. With his +newly acquired fondness for the haunts of men he has suffered a change +in this respect also. Whatever may have been his reason for migrating, +it no longer holds. He now finds himself quite able to stand the cold +of winter. Accordingly he never leaves us, except very temporarily. +When the migrating season comes the sparrows of the neighborhood are +very likely to gather themselves together in a single group and take +to the neighboring country. I believe this flocking on their part at +this time of the year is a remnant of the old migratory habit. Until +snow covers the ground the sparrow is not likely to be seen again in +such numbers in the city. The advantage the sparrow gains over his +competitors by not going south does not appear during winter. When +spring comes, however, his gain is evident. He has his choice of all +the nesting sites in the region. When the migratory birds return every +first-class place is filled by a sparrow's nest. Nothing but second +choice situations remain, and with these the late comers must be +content. When we consider how much the safety of the next generation +depends upon the security of the young while helpless in the nest, we +appreciate what the English sparrow has gained by staying throughout +the year. Often while the season is so inclement that it would seem +there is still danger of frost, the sparrow builds her nest. All sorts +of places are open to her choice. She will find a protected corner +under a roof, above a spout, in the corner of the porch, behind an +open shutter, in the vines against the side of the house, on top of an +old robin's nest in the tree, in the bird boxes which have been put up +for more desirable creatures; anywhere and everywhere this industrious +little mother is liable to build her nest. Her husband will help her +more or less in the task, often bringing material and helping to place +it in the negligent pile of which their nest is composed. But he does +a good deal more fussing and cheering up than he does actual work, and +she seems to depend much upon his cheerful presence for her happiness. +It is hard to discourage Madam Sparrow when once she has set her mind +on home-making. A bird-lover, some time since, reported how a pair of +sparrows had started to build a nest upon his lawn. He, wishing to +interfere with the process, took a small rifle and shot the male bird. +Within twenty minutes the female, who had scouted round the +neighborhood, returned with another mate and resumed her nest-building +process. Again he interjected the tragic note into her life by +shooting her second husband, only to find her start out in pursuit of +a third, with whom she returned in the course of an hour. He felt that +by this time he had interfered with her domestic happiness as much as +he had any right to do, and suffered her to continue her housekeeping +with her third husband without further molestation. I imagine it would +have puzzled both birds to tell who was the father of the nestlings +who appeared two weeks later. + +Not only do sparrows nest early, they nest often. I suggested to one +of my students that she locate as early in the season as she could the +nest of a pair of English sparrows, which was sufficiently accessible, +and that she keep it under observation at intervals of a few days +throughout the summer. In the fall she came to me with glowing eyes +and gave me her report. "It is simply great," she said. "I never went +to that nest a single time this summer to find it empty. When I first +got there I found four eggs; after a while these hatched out, and the +young were on the nest until they were old enough to fly; but before +they had left she had slipped a fresh egg among them, ready to start a +new batch. Whenever I saw the nest throughout the entire summer, I +found in it either eggs, or young, or both." Such reproductive energy +as this is hard to beat; compared with this rate of increase, the +ordinary bird is the exponent of race suicide. How can a robin hope to +compete with this family industry? What can a bluebird offer that will +approach such chances of a worthy successor when his work shall be +finished? + +These, then, are the most important points in which the English +sparrow has varied from his sparrow cousins and made of himself the +most successful town dweller in the bird world. He has become clannish +and gained the advantages of cooeperation. He has used man's highways +and cars by means of which to expand his area. He has cultivated the +presence of man and thus gained protection from his enemies, food from +man's waste, and nesting sites on man's house. He has assumed a varied +diet. The male has become handsome. He has given up migrating, and +thus secured the best nesting sites. He has learned to produce many +offspring. With all his versatility, why should he not succeed? + +Thrown into competition with our native birds, he easily beats them +on their own ground. He survives against the competition of birds +which seem to us more estimable in every way. The very fact that he +survives proclaims his superiority over them, and shows that our +criterion is not the one by which nature judges. We like the birds +which serve our purpose. We admire the brilliant plumage of the jay, +cardinal and goldfinch. We love the mellow notes of the woodthrush, +and of the veery, the clear, rollicking outpourings of the bobolink, +the musical love song of the brown thrasher, the cheerful scolding of +the wren. We are fond of the birds who busy themselves taking the +insects out from among our grain and from off our fruit trees. We can +only understand the value of the bird to nature when he is valuable to +us. So, because the English sparrow does little that is to our +advantage and much that is to our annoyance, he is in our estimation a +reprobate and an unending nuisance. + +All sensible bird-men must clearly acknowledge that he is a very +undesirable citizen. I write the above sentence to show that I realize +the whole duty of the bird-lover in the matter of the sparrow. This +pestiferous creature should be exterminated by traps, by grain soaked +in alcohol, or strychnia, by fair means or foul. But personally, I am +taking no share in his destruction. Any bird-lover, after reading the +foregoing account, can scarcely have missed the undercurrent of my +affection for the little rascal. He is a thorough optimist; he is +absolutely persistent; no hardship seems to dampen his ardor. His +heart is valiant above that of most birds so that he has dared to make +of man his near neighbor when other birds consider him their worst +enemy. I love him for it. When I am in the midst of a big city with +its cliffs of offices and its gorges of paved streets, it is to me a +cheer and a delight to see this happy little fellow who has adapted +himself to circumstances against which no other bird, excepting the +pigeon, can cope. I confess that it would be with regret that I should +see him disappear from the landscape. I have missed a long line of +spring peas through his ravages, and he has objectionably decorated +many places about my own home. But I have yet the first violent hand +to lay upon the sparrow, and I doubt whether my hand is ever to be +reddened with his blood. + +I am going to ask bird-men to forgive me if I say that I believe, +although I speak only from general impression, and not from careful +research, that the sparrow within the past eight years has reached his +equilibrium in the neighborhood of Philadelphia and is growing no more +abundant. Meanwhile another and very desirable state of affairs is +arising. Bird love and bird protection are so active in this +neighborhood that there is growing to be a new race of birds who lack +the fear of man their ancestors justly had. Under these conditions the +wild birds, which for a while we believed to have been completely +driven out by the sparrow, are rapidly returning to our villages and +towns, and we have many more robins and catbirds, wrens and flickers +than we had ten years ago. We have seen the worst of the English +sparrow; he has now found his equilibrium. + + + + +CHAPTER IV + +ADAPTATION FOR THE INDIVIDUAL + + +Among the standard books of the classical curriculum in the +denominational college of thirty years ago was a volume which I +suppose has practically disappeared from such courses. It delighted +many of its students for a reason entirely different from that which +the author meant should be its taking feature. It was Paley's "Natural +Theology." The author started with a story of a watch found by a +savage. This child of nature was supposed to examine its mechanism and +to infer that the watch was made for a definite purpose. As I +remember, he was even supposed to discover that its purpose was to +mark time. It was at least to become clear to his savage mind that +this was no chance object, but was the definite product of a designing +mind. Having brought this hypothetical savage to these conclusions, +the author turned himself to savages nearer home who fail to see +design in nature. The book takes up a great many cases of interesting +facts in animals and plants as clearly showing evidences of design as +did the watch our savage picked up. But the inference we were expected +to draw was that the design shown in nature argued clearly for a +Designer above nature; in other words, that nature was unintelligible +without God. Everyone in the class believed in God without this +preliminary, and consequently the book was unnecessary, so far as we +were concerned. We started with the condition of mind which the author +hoped to produce. One effect the book did have; in the absence of any +other reputable course in zooelogy, it gave us an astonishing +collection of interesting facts about animals. + +Some of Paley's statements were certainly peculiar. His Malay pig with +its upper teeth wonderfully curved was said to be in the habit of +hanging its head upon a bush while it slept, in order to save the +strain upon its porcine neck. This was too much even for our +credulity. None the less the impression made upon some of us by the +evidence for design in nature has never left us. + +Among many scientists to-day it is supposed to be crude to speak of +purpose in nature, and there is reason for their attitude. But the +statement that there is no such plan conveys to the ordinary thinker a +meaning that is far more erroneous than could possibly exist in his +mind should he believe implicitly in design and purpose. As between +design in the universe in the usual sense of the word, and a purely +accidental connection of events in the universe, there can be no +doubt as to the choice. The truth is far better expressed by the word +design than by the chaos which is the alternative idea in the average +mind. In these later years we have come to use a different word. We +now conjure in such connection with the word adaptation. In every +animal and every plant the trained eye sees unending examples of +adaptation; that is, of a fittedness to the work it has to do. The +modern scientist feels sure not only that the animal is fitted to his +work, but that he has been so fitted by the work; that the very use he +makes of his organs has determined their structure. This work has +decided that the structure which he has is the structure that shall +survive and shall produce other structures like itself. Adaptation +therefore does not simply express the idea that the animal is adjusted +to its surroundings, but it further suggests that the animal by +gradual process has become thus adjusted. The word adaptation applies +not simply to the result, but also to the process. The scientist does +not consider the animal a final and complete result. He thinks it +still in a state of flux, and so long as its line lasts it will be in +a state of flux. Change is about it on every side, and it must adapt +itself to this change or it will pass away. It may adjust itself, as +has been previously stated, by moving to another environment in which +it feels more at home, but unless it does this, if there come much +change in its present surroundings, it must either meet the +difficulty by altering itself, or it must give up the struggle. The +alteration is unconscious so far as the animal is concerned. It is +seriously to be doubted whether there is any recognition of the +process on the part of any animal excepting man. But though the +process be unconscious, it is none the less there. Slowly and +gradually the animal and the environment are becoming adjusted to each +other. + +While it is exceedingly difficult to lay our hands on any animal which +is at present visibly changing its structure, it is not hard to find +closely related animals. These are nearly alike in structure in most +respects. In a few points, however, they may differ materially, and +these points are often directly concerned with different habits of +life. Considered in this aspect, these adaptations of a single organ +separately examined form an excellent argument in favor of that +gradual alteration of the entire organism which evolution suggests. + +The most primitive struggle in which an animal can possibly engage is +the effort to maintain its own life and vigor. This struggle will +result in certain adaptations for the individual, adjustments which +make for the safety of the animal himself. These form the subject +matter of the present chapter. + +The farther up the animal kingdom we pass in the study of adaptation, +the more likely we are to find changes which have but little bearing +on the safety of the individual. They work for the good of the entire +species, sometimes to the distinct disadvantage of the individual. The +King Salmon may make its long run to the headwaters of our western +rivers, deposit its eggs, have them fertilized, and then float down to +death. But it does not die before abundant preparation has been made +for the continuance of the race. Such adaptation for the good of the +species will be considered in the next chapter. + +The first and most important struggle any animal has to enter is the +never-ending battle for its food. Occasionally there is a similar +straining after the air it breathes. But ordinarily air is +sufficiently abundant, except to animals living in the water, where +the supply is always more or less restricted and easily becomes +exhausted. But food is the constant need of every organism, and most +creatures die for lack of it. In this struggle the animal is pitted +against those of his own kind, rather than against those of other +species. Even his brother is his enemy, for he desires the same food. +In many a nest of birdlings one of them fails to reach its development +simply because the parent either is unable to find or it cannot carry +enough food to satisfy all the hungry mouths in the same nest. Before +the nestlings are ready to take their place in the struggle for life +outside and hunt their own living, one or more of them has succumbed. + +After the battle for food comes the struggle for shelter. For most +animals there is no such thing as shelter. They are exposed to the +inclemencies of the weather and to the depredations of their enemies +without the means of retiring into any situation which might protect +them. In the higher animals, especially when they are warmer blooded +and their bodies must be kept at a higher temperature, some form of +covering has come to be almost universal. + +Though comparatively few animals are prepared to seek shelter from the +cold, all of them have enemies against whom they must battle. These +foes may wish to eat them or may simply wish to get them out of the +way. In either event this struggle is so persistent and so keen that +after starvation it is probably the source of the largest loss to the +animal kingdom. + +Considering first the feeding habits of animals, we find they are +exceedingly varied. Some creatures simply engulf other and more minute +animals, often only microscopic in size, in such quantities as to +satisfy their hunger. Others, feeding upon larger plants or animals, +must have some means of breaking off particles of this food; still +others confine themselves entirely to nutritious fluids, and must have +organs adapted to this particular type of food. + +Insects are so common that anyone, who cares to, may easily verify +what is here described. It will take nothing but a clear observant eye +and a little patience to make out what is suggested. Each of our +common insects has one of two clearly defined habits in the matter of +food. Either it eats solid food, which must be made fine before it can +be taken into the mouth, or it feeds upon liquids. These liquids may +be easily accessible like the nectar of flowers, in which case one +sort of mouth will serve; or they may be the juices inside the tissues +of animals and plants, when an entirely different type of mouth must +be employed in their acquisition. Perhaps the most easily found +representative of the biting type of mouth, which breaks up solid +food, will be seen in the common grasshopper. Doubtless each one of my +readers has at some time taken a grasshopper into his hand, and, +holding the tip of his finger against the insect's mouth, has promised +the creature its freedom on condition that it disclosed its +reprehensible habit of chewing tobacco. The grasshopper surely +complied, and I trust the promiser was as good as his word. The +grasshopper's head is so placed that, while it is at the front of its +body, the mouth is directly on the under side of its head, while the +eyes are at the top of the front of its face. Under these +circumstances it cannot see what is going into its mouth, and this +makes an interesting variation of conditions to which it must adapt +itself. The means by which it accomplishes this will be clearer if the +mouth of the grasshopper be compared with our own. Our lips are upper +and lower, but the grasshopper has a front lip and a hind one. The +broad front lip is easily seen at the forward side of the mouth. Just +behind it, serving the purpose of our teeth, is a pair of hard jaws +with horny tips upon them, which serve to break small pieces from its +food. While our jaws and those of all other backboned animals work up +and down, so that we may be said to have an upper and lower jaw, the +grasshopper and all of his insect, crab, or spider relations, which +have jaws at all, have them right and left, and they work from side to +side. Behind these harder mouth parts is found a pair of softer jaws, +each of which has on it a little finger-like feeler. With this pair +the insect holds its food while the hard jaws break it to pieces. The +hind lip follows, and is also provided with short finger-like feelers. +The feelers on the hind lip and on the soft jaw are necessary because +the eyes are so placed as not to be able to see what goes into the +mouth, hence the insect must make up for the loss of sight by the +addition of touch. The same type of mouth as the grasshopper has will +be found among the beetles. Here the males sometimes have the hard +jaws so enormously enlarged that they are known as pinchers and have +given to their owners the name of pinching bugs. All insects with such +jaws as these use them for breaking up solid food. + +A glimpse at the mouth of the butterfly captured on an adjoining +flower will show a most remarkable variation from that seen in the +grasshopper. Practically all of the mouth parts mentioned are present +in this insect, and its early ancestors had their organs practically +like those of the grasshopper. Now they are so modified and united +with each other as to be almost unrecognizable. The pair of soft jaws +has become very much elongated, and they lock together in such a way +as to enclose a hollow space between them through which the creature +can suck its fluid food. Not only have these soft jaws joined +together, but, because they have become so much elongated when not in +use, they must be coiled up like a watch spring and laid between two +hairy lip-like processes which correspond in reality to the two +finger-like feelers of the grasshopper's hind lips. + +The butterfly, lighting upon the corolla of the flower, uncurls this +long "tongue," and through its hollow center pumps up into its crop +the nectar which the flower has stored in its base. When the butterfly +comes to get the nectar from the flower, it rubs upon its own hairy +body pollen from the stamens of the flower and carries it to the +pistil of the next flower of the same kind which it visits. Most of +us have at some time sucked the nectar from the back of a torn +honeysuckle blossom and approved the taste of the butterfly in this +matter. If the airy creature be watched as it lights upon a flower, it +will not be difficult to see it uncurl this long tongue and probe the +depths of the flower. If the butterfly be taken in the hand and the +tip of a pin inserted in the center of the coiled tongue, it can be +uncoiled without the slightest harm to the butterfly. + +Insects which wish to use for their food the juices of other animals +or of plants do not find them so easy to gather. In the mosquito most +of the mouth parts are developed into slender pointed bristles wrapped +in a hind lip. These bristles serve to puncture the skin of the +creature attacked, while the curled lip serves as a tube through which +the blood may be extracted. + +If, while sitting on the porch on a warm summer evening, mosquitoes +begin to annoy, let one of them at least serve to show his method of +procedure before he is destroyed. Allow the creature to alight upon +the back of your hand and slowly raise the arm until the eye looking +at near range can see the head of the mosquito, which, by the way, is +sure to be a female. Males in this species are entirely harmless. They +never eat after they have grown up; that is, after they are truly +mosquitoes. But the female is very assiduous. Alternately raising and +lowering her lancets from either side, she pierces, then saws, her way +down through the flesh until she has buried her instruments in her +victim and her head rests against her prey. Now a pumping motion of +the abdomen will be apparent, and this continues its accordion-like +action until it becomes more and more distended. The insect only gives +up its task when the entire abdomen is swollen into a great red ball +of blood. The mosquito will now slowly withdraw its instruments and +retire from the scene, if permitted to do so. If there is any fear of +annoyance from the bite, a drop of ammonia immediately applied will +counteract any irritation which would have been produced by the saliva +of the mosquito. The insect is not intentionally vicious in this +procedure. It is simply gathering its own natural food, though this +does not make it less annoying to us since we are its victims. The +swelling produced after the bite is the result of the action of the +saliva the mosquito injected into the wound. The opening through the +tongue is so small that blood would readily clot inside the tube and +prevent its further usefulness, did not the mosquito inject the +secretion of its salivary glands into the wound. This acts upon the +blood in such a way as to prevent its coagulation. + +Anyone who thinks carefully can add numberless specializations for +food getting. For instance, primitive mammals have little pointed +teeth which fit them for feeding on insects. In each of the great +order of mammals a special development of these teeth has occurred. +Among the rodents or gnawing animals the front teeth have become long +and chisel-shaped for nibbling. The horse has formed them for nipping, +and his hind teeth for grinding. In the dog the teeth near the front +have become long for tearing his flesh food, while his hind teeth, +working with the motion of scissors, cut it into pieces. + +A second great class of specialization is seen in the changes of habit +that provide the animal with shelter. The home seems so necessary a +part of human life that it is almost impossible to think of an animal +having nothing that in the faintest degree could be called a home. We +at least expect it to have some sheltered place in which it passes +most of its time and to which it returns after its wanderings. The +great majority of all animals have no such home. The place in which we +find them to-day may not be the place in which they will be to-morrow. +All places are alike to them. The ordinary conduct of their daily life +drives them about in the search for food. Their attempt to escape from +their enemies leads them each day into new situations, and they may, +and probably do, have no power to recognize the old location if they +return to it. When we come to the backboned animals there is a little +more tendency to a stationary location. The sun fish may frequent the +same reach of the stream, the trout may haunt the same pool, year +after year, but a great majority of fishes doubtless move +indiscriminately up and down the stream or about the lake or ocean and +are not found two successive days in the same place. The same may be +said of frogs. For a time a particular frog may have a fondness for a +special bend in the stream, but it is only a temporary fondness, I +believe. + +Our own need for shelter is the prime motive in leading us to build a +home, and this necessity arises first of all because of our warm +blood. What we are accustomed to call cold-blooded animals are not +truly so. Their blood holds practically the temperature of their +surroundings. As the air or the water in which they live grows warmer +or colder the bodies of these creatures alter with it. Consequently +they are active when the temperature is high and grow more sluggish as +the thermometer falls. When the day grows distinctly cold the animals +may go practically dormant. + +Only the birds and mammals have warm blood, and of these the birds are +distinctly the warmer. Whereas the temperature of the mammals runs +from about ninety-eight to a hundred degrees Fahrenheit, that of +birds lies somewhere between one hundred and five degrees and a +hundred and ten. Creatures which are warmer than their surroundings +must have some protection against chilling. Accordingly both mammals +and birds have clothing. In the case of mammals the covering is fur, +in the case of birds feathers. In some of the tropical animals like +the elephant and rhinoceros, or in man, who has learned to protect +himself in cold regions by making clothing for himself, this hair is +very short, and except where serving for ornament is quite scanty, no +longer being of use as a protection. But the great majority of all +mammals are well covered with a dense coat of hair. In many of those +living in the colder regions there is in reality a double coat. The +fur seal of the Alaskan Islands is so provided. A set of long hairs +deeply fastened in the skin forms a covering, which shows on looking +at the seal. Underneath this layer, and set but lightly into the skin, +is a short coat of very much finer hair known as the underpelt. When +the skin is taken from the seal it is split by machinery into a lower +and an upper layer. When so split the deep-seated pits of the long +hairs are cut, and these hairs come out. The fine underpelt thus laid +bare is what is commonly known as sealskin. Fashion has decreed that +this must be dyed a rich brown, although when taken from the animal it +is nearly mouse gray. + +The birds have need for better clothing. To begin with, their blood is +much warmer, and hence needs better protection from outside cold. In +addition such of them as fly high must be prepared to stand great +variations in temperature. For these purposes birds need a covering of +the finest type. This clothing, in addition, must be extremely light +because the creature must carry it into the air in flight. All of the +requisite conditions are thoroughly met by the feather, which is the +lightest and warmest clothing known to man. If at night we wish, +regardless of expense, to keep ourselves warm with the lightest and +warmest of covering, we send to the Arctic Sea, and from the breast of +the eider duck we pluck the down which lies between the warm blood of +the duck with its temperature of one hundred and seven degrees and the +water in which the iceberg floats. + +Young mammals and birds, before their clothing has well formed, are +naturally susceptible to cold; this leads to the first genuine +approach to a home among animals lower than man. Birds lay their eggs +long before the creatures inside of them are ready to emerge. +Accordingly they have learned to build nests in which to place these +eggs, and to protect them from the outside air; meanwhile the bird +keeps the eggs warm by close contact with its own body. The lowest of +the birds may lay their eggs simply on the ground without any special +protection. As we rise in the scale of the bird world we find nests +provided for the eggs. These nests become increasingly complex and +specialized, until we reach the oriole's home with its wonderfully +woven mass of fiber, which, in spite of its apparent looseness, +supports well the weight of the mother bird and of her eggs. The +robin, not content with making a woven basket, plasters it with clay, +and makes an absolutely impervious nest. + +When we remember that both mammals and birds are the modern +descendants of cold and scaly reptiles of an earlier geological time, +it becomes interesting to compare their clothing. Evidently in the +mammals hairs began to come out between the scales. Gradually the +scales became fewer and the hairs more abundant until finally the +scales have all disappeared, except those that remain as the claws on +the toes. The ancestors of the birds, on the other hand, boldly +transformed their scales into feathers. + +Another need for shelter arises in connection with the approach of +winter. This problem of withstanding the cold season is complicated by +the presence of two new factors. First and most directly, the cold +itself is a distinct obstacle to the comfort of many of these +creatures; as a secondary result of this cold, the food of many +animals disappears entirely in winter. Most of our birds meet this +difficulty by changing their base of operations. When the north grows +cold these creatures fly to the south. Some of their migrations cover +enormous stretches of country. Our bobolink, so well known and loved +by all watchers of spring migrations, passes twice a year between the +latitude of New York and Rio Janeiro. One of our most careful students +of bird migration says that the Golden Plover makes, twice each year, +the long journey from the Arctic shores of North America to the plains +of La Plata. + +Different fur-covered animals have specialized to meet the winter by +any one of three different methods. They may brave it out, hunting for +their food as best they can all winter long. Such a course is pursued +by the rabbit. Again like the squirrel, they may store large +quantities of food during the summer, and on this provender they may +subsist during winter, remaining for most of the time near their +hiding-places, which, however, they may frequently leave upon warm +days. A third method is less common, but very interesting. The +groundhog or woodchuck is the best-known example of the group. It +remains asleep, or, as it is technically known, dormant, during the +winter. This stupor is more profound than ordinary sleep, and from it +these animals awaken with difficulty. It is needless to remark that +the groundhog's behavior on the second of February has no relation +whatever to the weather we are to have later in the season. This is +coming to be pretty generally understood. While the newspapers each +year comment upon the groundhog and his shadow upon that day, year by +year the notice has more of humor in it, and fewer people pay any +attention to it. + +As for the backboned animals which are cold-blooded, these must, +unless they are fish, give up the struggle completely, bury themselves +in out-of-the-way places, and go worse than dormant. They often become +absolutely cold and stiff. In the case at least of fish, it is quite +possible for them to be frozen stiff, even to be enclosed in cakes of +ice, and still to recover if the encasement is not too long continued. +But the snakes, the turtles, the toads, the lizards, all are hidden +beneath the ground waiting in absolutely unconscious rest the return +of warmer weather. + +After the need for food and shelter comes the continually recurring +necessity on the part of almost every type of animal to escape from +the unwearying persecution of higher creatures which would feed upon +it. The whole creation is a constant network of animals which prey +upon each other. It is the fate of a great majority of all creatures +to fall victim to other animals to whom they serve as food. +Accordingly nature has concocted many devices by which she assists +her favored children in escaping this relentless persecution. Perhaps +the most widespread means which animals have developed in order to +elude their enemies lies in the possession of power to escape their +attention. Two different factors may contribute to this end. The first +of these consists in the practice on the part of many animals of +remaining absolutely quiet in time of danger. This instinct seems to +be nearly universal. The first impulse of most animals upon +discovering danger is to remain absolutely motionless. The eye +detects, with ease, objects in motion. These same objects might +entirely escape attention were they quiet. A mouse could remain in the +corner of a room for a long time without attracting the eyes of the +occupants of the room. Let it but scamper across the corner, and at +once it is discovered. It is quite conceivable that early animals were +divided in the matter; that the impulse of some was to escape from +danger, while others, frightened by the presence of the enemy, +remained absolutely still. Each plan has succeeded. Those which, on +running, ran fast enough to escape became the parents of others like +themselves, led eventually to a line of animals in whose speed lay +their safety. Those, however, which attempted to escape, and failed +because they were not swift enough, had their line cut off, and were +thus less likely to be represented in the following generation. The +constant result of errors along this line would be to destroy the slow +and preserve the swift, and in the course of time it is quite +thinkable that only the swift should remain. As the movements grew +more and more keen, even the slower of these would pass out, thus +tending always to produce the succeeding generation from those who +were most rapid, and hence most likely to transfer to their children a +similar power. + +But there is another tendency of animals which leads them when +frightened by their enemies to remain quiet. If this impulse is obeyed +thoroughly enough, it is easy to see how the owner of this habit might +entirely escape detection by his enemy. Any restless animal unable to +restrain his nervous agitation naturally betrays his presence and is +picked off. The result of evolution along this line would be the exact +reverse of the preceding. Those that lay most absolutely quiet would +be the parents of succeeding generations, while those who were slow in +coming to rest, or were indifferent about remaining quiet, were picked +off, and their tendency eliminated from the future of the species. In +this way many animals have come to keep entirely quiet in the presence +of danger. It is not a sign of high intelligence. As a matter of fact, +it is rather a stupid procedure, so far as the animal itself is +concerned, but it is a preserving stupidity, and many animals have it. + +The "June Bug" (which is not a bug, but a beetle, and arrives in May) +has this interesting habit of keeping quiet. If in its flight it +strikes the globe of an electric light, it falls at once to the +ground, and remains perfectly quiet for a time. After a short interval +it recovers and starts out to regain its previous activity. But this +recovery is by slow stages, and the whole procedure on its part looks +exceedingly stupid. + +The little snake with flattened and expanded head, known as the +blowing viper, or puff adder, is one of the most amusing +representatives of the tendency to "play dead" that could well be +found. If you strike him the faintest blow with the lightest stick, he +at once goes into apparent convulsions, in which he seems to suffer +the greatest agony. Then, throwing himself upon his back, he, to all +appearances, yields up the ghost. If, however, you retire but a slight +distance and keep your eye upon him, you find that his ghost returns +after a comparatively short absence, and he slinks away out of danger. +This is the most effective exhibition of this kind with which I am +acquainted. + +As for the habit of "playing 'possum" on the part of our opossum, the +trick would seem to be particularly inane. The truth of the matter is, +what is attributed to an unusual brilliancy on the part of the +creature is positively unusual witlessness. The animal has an +exceedingly small brain, as compared with that of a dog of similar +size, and to anyone who knows brains at all this particular organ +would not be looked upon as furnishing its owner much ability. The +fact is that the opossum has exceedingly small wit, and this little +deserts it in an emergency, as a result of which he grows helpless and +motionless. This is often supposed to indicate great wisdom. There may +be wisdom in it, but it is the wisdom that lies back of all nature. It +certainly is not the wisdom of the opossum. + +Man himself possesses to a marked degree this impulse to keep quiet in +danger. The man from the country who is visiting the large city, +suddenly startled by the "honk" of the auto horn, finds his power of +movement promptly arrested, and he is not unlikely to be struck and +injured by the machine from which the city dweller would easily +escape. This is not particularly to the credit of the city dweller, +who, when in the country, may find himself similarly startled by the +sudden appearance of the calf, the pig, or the sheep. The bull, which +a country boy, accustomed to him from childhood, will drive with a +willow switch, is a source of terrified concern to the city man. + +While the trick of keeping quiet serves many an animal in time of +danger, there is another device for escaping attention, far more +common and widespread throughout the animal world. The eye does not +easily see an object if it is colored like the background against +which it stands. A host of animals find their main safety in being +indistinguishable in color from the surface on which they live. There +are many biologists who seriously question whether protective +coloration, as Darwin called it, is as effective as he believed it. In +some quarters it is the present fashion to doubt protective coloration +entirely. No one has yet shown any principles which will better +explain the great color scheme of the animal world, and until such +explanation is forthcoming I believe it will not be wise for us to +discard the idea of protective coloration. No doubt it has been +overworked by enthusiastic believers in its efficiency. At the same +time, to overlook it completely, is, I believe, to make a greater +error. I have little doubt that when the broader explanation comes, +which will satisfactorily explain the color scheme of the animal +world, the idea of protective coloration will be found, not so much to +have been wrong, as to have been but partial. It will be included +under the broader principle which takes its place and will not be +supplanted by it. + +The idea of protective coloration is that very many animals have +ordinarily come to be colored like the background on which they live. +The process has taken many generations, and is very slow, but is none +the less sure in the end. In most cases the animal is probably +entirely unconscious of this point in its favor, and usually it does +nothing to assist the deception. The result is none the less effective +because the animals themselves are unconscious of the process. The +cabbage worm is green in color like the cabbage. This does not mean +that it got green by eating cabbage or by longing for greennesses. +Through long years the enemies of the cabbage worm have been picking +it off the plants on which it fed. This does not imply that cabbages +as we know them are very old, but cabbage worms doubtless ate the +leaves of the sea-kale long before man had cultivated it into cabbage. +During all these years the enemies of the caterpillars, generally in +the shape of birds, have been assiduously gathering them up. + +When we see how much the various members of the same human family may +differ in complexion, how much the various pigs in the same litter may +differ in size and in coloration, it is easy to understand that among +these caterpillars which have eaten the cabbage there must have been +considerable color variations. I do not imagine for a moment that the +birds had any preference for any particular color in their cabbage +worms. They took every caterpillar they saw, but they naturally first +saw those that were least like the background on which they lived. +The only caterpillar which was effectively hidden from his enemy was +the one that was indistinguishable on the leaf. If it escaped in this +way, the probabilities are that it would produce young which would be +at least a little more likely to be green in color than the progeny of +its darker-colored brothers and sisters. By this continued process the +birds steadily weed out the darker-colored specimens. There would +result, in the course of time, a race of caterpillars, whose ancestors +for so many generations back had been light green in color, that there +is little likelihood of any of the older and darker forms turning up +again. In the course of time all dark tendencies will have disappeared +from the family and practically all of the group will be light green. +Any sport or variation in the shape of greater conspicuousness would +fall a quick prey to the enemy and its line be cut off forever. + +The same sort of activity has resulted in the peculiar green color of +the katydid. This creature lives chiefly upon the leaves of trees and +shrubs. This insect is so large that, even though it is leaflike in +color, it might still be conspicuous. As a result those katydids whose +wings were most like leaves in form were least likely to be picked up +by the passing bird. This sort of protective appearance is intensified +by exactly the same means as that which brought about protective +coloration. The katydid least leaflike in appearance was eaten first. +Thus those most leaflike remain until the last, and are most likely to +produce young. Again, it was not the fact that they lived among leaves +which made them look leaflike, but it is because they look like leaves +that they escaped being devoured. + +The katydid has materially assisted in its own preservation by being +active chiefly at night. In the daytime it keeps comparatively quiet. +Thus seated upon a twig, especially if hidden among the leaves, it is +almost unnoticeable. At night, however, it moves about more freely, +seeking its food and eventually its mate. At such times it becomes +distinctly more conspicuous because its wings are steadily fluttering. +The hind wings are filmy and are very light green. The creature looks +most ghost-like as it flies through the evening air. + +A very similar history lies back of the coloring of the ordinary toad. +Though descended from the frog, and originally a creature of the +water, the toad has long since adapted itself to live upon the dry +ground. It still produces its young in the water as it did when a +frog. Whereas the childhood of the frog, that is, its tadpole stage, +is very long and it assumes its adult form comparatively late, just +the reverse is the case of the toad. The young hasten through their +tadpole stage within a few weeks, and assume the shape of the parent +toad when about big enough to cover your little fingernail. Now they +leave the water and seek dry land. Naturally they make the change when +the land is damp, that is, after a warm spring rain. People seeing +these multitudes of little toads hopping around over a bare spot of +ground, and remembering the rain of the night before, insist that it +has rained toads. Of course it never rains down anything which cannot +evaporate up. The stories of showers of toads and of earth worms, with +an occasional fish, or even creatures of larger size, are all pure +myths. There are conceivable tornadoes after which there might be a +shower of such creatures, but at such a time it is likely also to rain +barn roofs and buggies. You may be sure that toads which come down in +the rain are dead after they strike the ground. + +The little toads started out, perhaps a hundred at a time, from the +small pool in which their eggs were laid. These creatures find dragons +on every side. The gartersnake comes along and gets his first toll; +the heron follows him and takes such as catch his hungry eye; the +turkey gobbles up his from what are left. By the time the toad-eating +creatures in the neighborhood have taken such as they found, there are +very few remaining. These doubtless have been left for a very good +reason, generally because they were not noticed. This was because they +looked like the ground on which they sat, and because they kept +perfectly quiet while the enemy moved about. This process has gone on +so long that the toad has come to be astonishingly well protected by +its resemblance to the ground. This likeness it intensifies by its +interesting habit not only of keeping entirely quiet, but of dropping +its nose to the ground, instead of sitting high on its front legs, as +it does when not in danger. + +I have noticed that if a snake and a toad be placed in the same cage, +when the snake approaches to capture the toad the toad drops into a +squatting position, and is very likely to blow himself up until he is +rounder in outline than he was before. Whether this is a deceptive +trick which makes him the more resemble a stone is more than I can +say. I do not remember having seen our eastern toad do it. I have seen +it happen a number of times in the laboratory of a Colorado +naturalist, and it is quite possible that in the open country more +sparsely covered with vegetation than is our ground in the east this +inflating device may serve the toad more effectually than if it kept +its own outline. + +Even among creatures far more active than the toad and the katydid an +inconspicuous color must certainly result in distinctly better +protection. Everyone knows the jay and the cardinal when first he has +seen them, if only he has a slight acquaintance with their pictures. +They are so conspicuous that we recognize them at once. More common in +my region than the jay or the cardinal is the red-eyed vireo. This +creature moves industriously in and out among the leaves of our trees. +It is persistently in motion, is nearly constant in song, and is a +bird of fair size, being larger than our English sparrow, though +smaller than a robin. Many a nature lover will recognize twenty-five +or thirty birds at sight without any difficulty, and not know the +vireo. Yet the vireo is more common than two-thirds of the birds he +knows. There can be but one reason for this; the bird is +inconspicuous. The olive-green of its back, with its light under +parts, serves to hide it completely amid the foliage. Even the +bird-lover learns to find it first by its jerky song, and then by +watching for its movements among the leaves. + +One aspect of protective coloration has been brought to our attention +by the artist, Mr. Abbott N. Thayer. He first clearly explained why it +is that animals are usually so much lighter on the under side than +they are upon the upper. Mr. Thayer proves his position by taking some +ordinary cobblestones and painting one of them a uniform color and +placing it upon a board painted the same color. One would think the +stone would be inconspicuous; as a matter of fact, is quite easily +seen. The underside of the stone, turned away from the light, is so +shaded as to mark a distinct boundary between the stone and the board. +Another cobblestone was colored on its upper side like the board, but +the color faded into a lighter and lighter tint until the bottom of +the stone was nearly white. This stone, placed upon the board, was at +a short distance nearly invisible. In other words, although the +pigment was actually lighter on the under side, it was so much less +intensely illuminated, that the result was the same in tint as the +other side under the clear sharp light of the sky. + +Many a person, looking down into the water from a bridge, sees nothing +whatever of the fish in the water below, because their backs are +exactly like the bottom of the stream. Suddenly one of the fish, by a +quick movement, turns its lighter under side over in such a way that +it is clearly illuminated from the sky. Immediately a flash as of +silver strikes the eye of the onlooker and makes him aware of the +presence of the fish which had previously been undetected. If rendered +thus suspicious, the observer will carefully examine the bottom of the +water, he may quite likely find dozens of fish which had previously +escaped his attention. + +Nature is very versatile. So many of her apparently chance ventures +have proved successful that she has retained many devices by which her +children may be safe. One of these, which is doubtless often quite +effective and may serve to save an animal's life, is that of being +able to emit an odor so nauseating as to offend the enemy's sense of +smell, and doubtless remove the keen edge of his appetite. It is not +uncommon among the group of insects properly known as bugs to possess +an exceedingly unpleasant odor. Anyone who has handled a squash bug +will know exactly what I mean, and there are other members of the +group not so common as the squash bug, which, at least to the human +nose, are distinctly offensive. Some of the beetles also save +themselves by this device. + +One of the most interesting developments of this peculiarity is found +in the case of the common skunk. This creature has in each groin a +gland capable of secreting a highly offensive fluid. Ordinarily this +liquid is kept safely within its sac, and for a long time none of it +may escape. When closely cornered, the skunk will turn its tail toward +the enemy and with a quiver and a flip of his tail it can guide the +openings of two little tubes that come out along the root of the tail +in such fashion as to eject the fluid in a fine and foul-smelling +stream against the animal from which the skunk would escape. Once +fairly hit by this fluid, I imagine most animals will drop the skunk. +A dog surely will, and will hate himself for having made the attempt +to capture anything which must be so ignominiously allowed to escape. +If ones clothing is well saturated with it, it is nearly useless to +hope to remove the odor. A dog will carry the smell for several weeks. +For a long time it will be so strong as to make him an unfit denizen +of the house. Even swimming in deep water does not remove it. After +two weeks, although he may seem to be practically free from the odor, +a light rain will bring it all out again and make him nearly as +offensive as before. + +Not as prompt in its action, but in the end nearly as effective, is +the protective device which the toad sometimes uses to his distinct +advantage. May I be pardoned a personal account of this particular +feature. It was my good fortune to be for a short time a student in a +class taught by Edward Drinker Cope, one of the most brilliant of our +American biologists. Prof. Cope mentioned in class the fact that the +Batrachians (the group to which the toad belongs) have in many cases +the power to emit from their skin a fluid which is sufficiently +nauseous to deter an animal from eating the creature that secretes it. +Upon such authority as this, I had no hesitancy whatever in repeating +Cope's statement. One morning I had a class in the field studying the +ground ivy, whose dainty blue flowers were lifting themselves out of +the dewy grass. While we were thus engaged, a toad joined the circle. +He came out of his dewy retreat clean and fresh from his morning bath. +I took him in my hands, and made him the subject of an immediate +lesson. I showed to my pupils his eyes and his interesting method of +handling them, his tongue and its strange insertion; showed them how +to look into his mouth and look up his ears to his ear drums, and +pointed out many other interesting facts. Then I told them how Cope +had said that the toad had power to emit from its skin a fluid so +nauseous that many an animal hesitates to eat it. This is the first +peculiarity I had mentioned which I had not myself observed, and a +scientific qualm came over my conscience. Why had I never verified +this statement which I had so frequently repeated? On the impulse of +the moment, with the bright, clean skin of the creature fresh from the +dewy grass, making it less than usually repulsive, I ran my tongue up +its back only to find that it had no taste whatever. I was of course +surprised, but I was not foolish enough to deny, as the result of one +observation, the statement of a good scientist. The observation, +moreover, was one which I naturally did not care to repeat with any +frequency. Of one thing I was sure, toads do not always have an +unpleasant taste. + +A year later I had a class down by the side of a neighboring pond. The +pool was not an attractive one, and I had picked from it a more than +commonly unappetizing looking toad, which proved to be a mother which +had not yet laid her eggs. As I held her in my hands and exhibited her +various points to my pupils, I told them of Prof. Cope's statement. I +also told them of my unsuccessful attempt the previous year to verify +the statement. I added, however, that I would not repeat this +experiment on this unappetizing specimen. Hereupon the toad not only +exuded, but squirted, from a gland over her left shoulder blade a +fluid, milky-like in appearance, and forming a jet as thin as a +needle, but ejected with force enough to strike my face, which was at +least fifteen inches away. I moistened my finger on my tongue, lifted +the fluid from my cheek, and tasted it. Cope was right. A toad can +exude a most nauseous fluid. Horsechestnuts extracted and distilled +might possibly provide something as bitter. Why did I not find this in +the preceding case? I have too few observations on which to base a +conclusion, but I have a suspicion as to the reason. In the case of +the toad which spurted the fluid in my face, we had a creature with +whose life were tied up the lives of her many offspring, to be +produced from the eggs she was so soon to lay. Under conditions like +these, nature is more than commonly careful of her children. Whether +this be the reason or not, toads do not always have an unpleasant +taste, but when they do it certainly is most unpleasant. + +There remains to be considered the most effective plan yet mentioned +of escaping the enemy, and that is of really escaping. In all the +devices we have considered thus far the enemy is eluded. When the +creature lies quiet, or finds safety in its protective coloration, or +in its bad taste, or unpleasant odor, it still remains in the presence +of the enemy. A more progressive plan altogether is to escape the +enemy by flight. The great advantage of this plan lies in the fact +that the acquisition is valuable for every purpose. The creature then +can escape the enemy, can range widely for food or for a mate. This +gives it an enormous advantage in the struggle for life. The power to +fly, in insects, was doubtless originally gained in the attempt to +escape the enemy. Among many of the lower animals it is nearly the +only purpose that flying serves. Later on it enables the animal to +pass from one food locality to another. In a few creatures it plays an +effective part during the mating season. These last are probably both +derived powers, and the original function was that of escape from the +enemy. The grasshopper has grown its long legs to serve him for +safety, and through them it is helped along, moving about chiefly by +leaps when it wishes to go any material distance. It is only toward +the very end of its life that the grasshopper has wings, and then they +serve probably to aid in the search for a mate. Among the birds flight +began simply in sailing out of the trees, into which the creature, +still half lizard, had crept to escape its enemy. The earliest bird +known to us had comparatively insignificant wings. There was really +more support in its tail than in its wings, and this would distinctly +indicate that it glided more than it flew. It had claws also upon its +wings, and it was probably the case that this creature crept into the +trees, at least in its earliest forms, and sailed down in a manner not +unlike that employed to-day by the flying squirrel. From such simple +beginnings came the wonderful power of flight in the birds. + +Among mammals the attempt to escape from the enemy has led to an +interesting development, which will be more fully explained in a later +section when we speak of the history of the horse. The early mammals +walked flat-footed, as we do on our feet and as the raccoon and the +bear do on theirs. Gradually, however, as their enemies became more +fierce and better able to injure the larger mammals, the latter gained +in power of flight, and this gain consisted first in rising from the +toes, lifting the heels completely off the ground. At the same time +the leg and foot were gradually lengthened. Doubtless in this way the +fleet animals, like the deer, the horse and the giraffe, first came by +their long legs. Constant elimination of the short-legged ones, by the +pursuing enemy, resulted in the selection of the long-limbed ones for +breeding purposes, and hence to the ultimate elongation of the legs of +the species. + +The method of escape from the enemy involves cowardice. "He who fights +and runs away may live to fight another day," and so it may be the +part of wisdom in the weak creature to escape from his enemy by +flight. It is a far more estimable process, from our standpoint at +least, to stand against the onslaught of the enemy and beat him upon +his own ground. This end is secured in many animals by acquiring horns +or by lengthening certain of the teeth. The horn is a very ancient +instrument of defense. When the reptiles ruled the land horns were not +uncommon. They consisted in those days of hardened scales, which +lengthened and fastened themselves over a core of bone. Such an +old-fashioned instrument, sometimes made of newer materials, still +remains the defense of a number of animals. The rhinoceros has upon +his nose a lengthened projection, which is what might not improperly +be called hair glued into a cone. This enormous horn is a frightful +weapon, both of offense and defense, and, when backed by the terrible +weight of the body of the rhinoceros, it can do as deadly work as +almost any instrument of destruction known to animals below the grade +of man. But, after all, this is an old-fashioned method, and the +rhinoceros is a relic. + +Among the carnivorous animals the teeth, which were developed first +chiefly for the tearing of flesh in its consumption, became effective +for their courageous owners. Because these tearing teeth are well +developed in the dog they have come to be known as canine teeth. +Usually where an animal can use its teeth effectively for offense or +defense, it is the canine teeth that are thus modified. The cat has +developed them better than the dog, and one of the cats of a bygone +geological period had canine teeth so magnificently enlarged and so +sharp at the back as to give this frightful creature the name of the +saber-toothed tiger. The long teeth in the upper jaws of the elephant, +commonly known as tusks, are not canine teeth. The elephant has +completely lost his canines. His tusks are his incisors, and they have +developed as have almost no other teeth in the mammals. + +These are only a few of the numberless devices nature has evolved for +furthering the success of her children. There are so many others that +to many of us they form almost the chief point of interest in our +study of a new animal, or our closer observation of an old friend. + + + + +CHAPTER V + +ADAPTATION FOR THE SPECIES + + +The strife, as we have described it thus far, is a purely selfish +struggle. Every point gained is a point favorable to the welfare of +the individual animal. But nature is uncommonly careless of the +individual unless the advantage gained is also of use to the species +as a whole. Very often the life of an animal ceases when provision has +been made for its young. The male garden spider may have a long and +dangerous courtship, in which the uncertain temper of his ladylove may +lead her to bite off four or five of his eight legs. But her +ingratitude is not yet complete. He may have barely accomplished his +desperate purpose of fertilizing her eggs at all hazards, when she +ends the process by eating him. The male bumblebee fertilizes the +female in the late summer and then dies. She does not lay her eggs +before the next season. So it happens that no bumblebee ever sees its +own father, and no father bumblebee ever sees his own children. In the +honey bee the male, which has been fortunate enough to fertilize the +queen, pays for his honor by death within the hour. Superfluous +bachelors, among the honey bees, when the bridal season has passed, +are driven from the hive to die of starvation. + +An animal need not always be successful himself, but it is more +essential that he hand down his successful traits to those who come +after him. It is more important for the future generation that an +animal should have had it in him to do great things, though he himself +really have never done them, than that he should have learned to do +great things on a meager original endowment. Not what an animal +accomplishes is important to his children, but what he has it in him +to accomplish. Accordingly Nature is full of devices by which those +who have proved their original endowment by winning out in the +struggle shall hand on this endowment to a subsequent generation. In +other words, Nature is anxious that they may successfully mate. Here +we are again on distinctly debatable ground. Darwin himself believed +thoroughly in what he called sexual selection. It is the essence of +this idea that the males and females have grown unlike, more +technically have developed secondary sexual characters, through the +choice of the mating pair. It would usually be the more serious loss +if accident should come to the female, for she may carry fertilized +eggs for some time. Hence, if both sexes may not become attractive, it +is usually the male that develops fine colors, ornamental appendages +or a captivating voice. + +An interesting reversal of this process has taken place in civilized +man. His more savage ancestor adorned himself more lavishly than he +permitted his mate to do. With the advance of civilization man has +undertaken to defend his own mate most valorously. The result is it is +safe for her to be beautiful. Under these circumstances, however, it +is more necessary to her welfare that her consort be vigorous rather +than that he be handsome. Hence in the human species beauty has become +the prerogative of the woman, and this is increasingly the case the +higher the civilization. Whether woman suffrage and self-support will +reverse this process remains to be seen. There are indications that +point that way. + +There are many biologists who are at present expressing serious doubt +as to the validity of sexual selection. As in the previous cases of +protective coloration, I believe it will be wise for us to retain, +even though with an interrogation point behind it, the idea of sexual +selection until such time as those who object to it have furnished us +with another theory which will more nearly account for the observed +facts. While entirely conscious of the possibility that there is a +weak spot in the theory, we will still tentatively hold to sexual +selection. The fact that beauty in women is so intensely attractive +to man, and that vigor and manliness in man are so attractive to +women, leads us to infer that among the lower animals, although of +course in a vastly less degree, vigor and beauty are also attractive. +The weakest point of the position lies in the fact that it probably +presupposes a higher degree of capacity for appreciation on the part +of lower animals than they possess. Those who deny the truth of the +theory laugh at the idea that a butterfly can see clearly enough and +care enough for what it sees to notice whether its mate has wings of +one type or of another. The size, number and position of the spots on +the wings of many butterflies are so nearly constant that they cannot +of themselves have been entirely determined by the choice of the +insect. Yet this may not preclude the possibility of the fact that, +while the spots were produced through some other agency, certain types +of them were selected by sexual preference. + +If attractive coloration is effective anywhere in the animal world, it +will possibly be found among the insects, but it is especially likely +to be found among the birds. Very many field workers in these groups +feel quite sure of the value of attractiveness. When butterflies chase +each other up and down, circling and doubling, following each other +for long distances, it would certainly seem as if they were pleased +with each other's appearance. Some naturalists, especially those who +have worked chiefly in the laboratory, insist that it is the odor, not +the color of these insects, which is attractive, and some experiments +which have been made would seem to point in this direction. But the +creatures experimented upon most carefully were night-flying moths, +and it is quite possible that the sense of sight in the night-flying +moths has lost its vigor. + +The great difficulty in understanding sexual attraction in insects, as +based upon beauty, lies in the undoubtedly lower development of their +nervous activity; in other words, in the apparent absence of anything +worth calling mind. I think no one imagines that a butterfly, looking +upon two other butterflies who are competing for her affections, +deliberates between them and determines to admit to the circle of her +friendship the more brilliantly colored male. Moths are so +irresistibly attracted to a light as to fly into it without apparent +power to withstand its influence. They repeat the flight again and +again until they are destroyed. If they react so vigorously to the +stimulus of the light, it seems not impossible that they may also act +vigorously to the stimulus of color pattern, and that the male most +beautifully colored, according to the nervous ideal of the female, +should win her unconscious regard. At least it is certain that, in +very many of the butterflies and moths, the attractive coloration is +chiefly displayed when they are moving actively about; and when they +alight and their enemies can the more easily capture them, they +conceal their brilliant colorings. Most butterflies are very brilliant +on the upper surface of the wings and very much duller on the under +surface. Hence in flight they show their colorings exquisitely, but +when they alight, and are thus more likely to be captured, they fold +the brilliant surfaces together in an upright position. In this way +not only is the dull side of the wings placed outward, but the wings +themselves are placed edgewise to the sky, and it is from this +direction that their enemies, the birds, are most likely to see them. +Once upon the wing these creatures display their beauty with much +greater safety because they can escape the birds very readily by use +of their exceedingly jerky flight. The butterfly's motion is as +irregular as any we have except the bat's. This eccentricity is one +great element in their safety, and makes it less dangerous for them to +display their attractive colorations. + +One very large group of the night-flying moths have been named the +"underwings," because of the fact that their hind wings are very much +more brilliant than the front, and in lighting they fold the dull pair +back over the bright, completely concealing them. These creatures are +in the habit of resting in the daytime against walls, or stones, or +the bark of trees. The similarity in color between their front wings, +which alone show while sitting, and the background on which they rest, +is most remarkable. One may pass them again and again, although they +are of considerable size, and not notice them at all. Once let them +display their hind wings and the brilliancy of their color always +attracts immediate attention. + +It is among birds, however, that brilliant coloration serves its most +effective purpose. The birds are alert, exceedingly quick of sight, +and are much more discriminating than insects in almost every respect. +It is not so impossible that these creatures might even voluntarily +prefer a distinctly more brilliant mate, though the voluntary +character of the process is not essential to its success. Men +certainly are constantly attracted to women for whose charm it would +puzzle them to account. If this is true with regard to men, it is +certainly probable that birds would be largely influenced by phases of +attractiveness, of which they were observant, but unconscious. + +Certain it is that in many birds the males are far more beautiful than +the females. Perhaps the commonest illustration, and, at the same +time, one of the best is found in the so-called red-wing or swamp +blackbird. The male of this creature is a brilliant black, excepting +that upon the angle of the wing, spoken of roughly as his shoulder, +though in reality it is equivalent to our wrist, there appears a +splendid orange patch with a border of lemon yellow. When he folds his +wing he pushes this colored angle of the wing so deftly under the +feathers of his shoulder as almost to conceal it. When in flight the +bird is exceedingly conspicuous, showing, with every bend and twist of +his body, his gorgeous epaulets. Meanwhile, the female is likely to +pass unnoticed. She is dull in color and streaked like the grass among +which she lives. During the mating season the male hovers about her, +swaying from side to side in such a way as certainly to make it appear +as if he realized his good points and was bringing them to bear as +effectively as he knew how. After his mate has nested and is rearing +her young, it would appear that the male uses his brilliancy to lure +the observing enemy away from the nest containing his wife and +children. + +Another illustration of the remarkable superiority of the male over +the female, in many parts of the bird world, is seen in the case of +the common barnyard fowl. The rooster is so much more gorgeous than +the hen that anyone reasonably acquainted with these birds cannot have +failed to notice the fact. In some of our modern varieties we have by +breeding colored them nearly alike. The original chicken is colored +much like the common Leghorns. Shades of red and yellow decorate his +neck and back, while the flight feathers of his wings and of his tail +and the sickle feathers which ornament the rear of his back and hang +over his tail are lustrous dark green. The hen meanwhile is very much +less brilliant in her contrasts. I shall speak more fully of this in +discussing polygamy. + +The attraction of beauty is not the only lure by which a creature may +win its mate. Sound may captivate as effectively as beauty. This is +true of insects as well as of birds. Certain insects at least advise +their mates of their presence by means of a sound which they emit. +This is particularly noticeable among the group of straight-winged +insects to which the grasshopper, katydid and cricket belong. The +grasshopper has a ridge on the angle of his wing and a roughness on +the side of his leg. When these two are rubbed together the result is +sometimes a fiddling, sometimes a snapping or cracking sound, +differing in different grasshoppers. I doubt not these sounds are +pleasing to the female of the species, for they are always made by the +male. The katydid, instead of fiddling in this way, has a sort of drum +on the angle of his one wing, which he can rub over a tooth in the +corresponding angle of his other wing, thus producing the familiar +"katydid" sound. I have never succeeded in making a dead grasshopper +fiddle, but I have long known how to make a dead katydid say "ka." +Quite recently I have added to my accomplishment in this respect and +can make it say "katy." The "did" part of the song still lies beyond +my power. The crickets produce their sharp notes in much the same +fashion as the katydids. + +One observer of the chirping of the cricket says that the pitch of the +song varies with the temperature. He has even worked out a formula by +which one can tell the pitch of the chirp, if he knows the +temperature, or, knowing the temperature, can determine the pitch. Of +course this is too mechanical; yet it indicates that there must be +considerable relation between the two; the warmer the cricket the +happier he is. + +It is the males among insects that chirp their love songs. The females +never answer them. There is a peculiar notion that the female katydid, +when thus accused of some offense, replies "katy didn't." The truth of +the matter is that no female katydid ever replied to the accusations +of her lover, if accusation it be. She is absolutely dumb, not having +the drum upon her wings with which to reply. She is provided with ears +wherewith to hear, and, strange to say, she keeps them on her elbow, +as does also the cricket, while the grasshopper has his ears upon the +side of his body. + +Everyone who lives in the country, or goes into the country in the +summertime, is sure to know the humming of the so-called locust. It is +an unfortunate fact that the word locust may have several meanings. It +is properly applied to one group of the grasshoppers. The creature +most commonly called a locust is a cicada, or harvest fly. When the +weather gets quite warm the cicada starts his love song. He has two +long flaps to his vest, and under each flap he has a vibrating drum +head. This is set shivering by a muscle on its under side. The female +cicada again is silent. + +It is among birds that the love song reaches its finest development. +It may consist simply of a little chirp as in the chippy. It may +consist of two notes of a different pitch repeated steadily, as in the +tufted titmouse. It may attain considerable variation, as in the +robin. But in the choir of our best singers, like the catbird, +thrasher, and mocking bird, there is unending variation of notes. It +seems almost impossible to doubt the charming quality of this voice +upon the mate. It certainly is chiefly confined to the mating season, +and is indulged in almost entirely by the males. This does not mean +that a male does not sing excepting when he wishes to charm his mate. +But the time when he is in his most exquisite feather and most +charming mood is the time when he sings most sweetly, and this is the +time when he is taking to himself a mate. The love joy may so +overcrowd his life that he sings much and often, but the increase in +its amount and character during the mating season seems to proclaim +its purpose beyond a doubt. + +In addition to the allurements above described there are certain +peculiar behaviors of the animal during the mating season which are +intensely interesting. Sometimes they consist simply of a wild +delirium of joy, which overpowers the animal completely and makes him +do wonderful things. Birds will fly with impetuous leaps in the air, +mount higher and higher, singing wildly, only to turn suddenly at the +top of the flight and drop promptly to the ground. I have seen such +ecstatic flights in the oven bird and in our rollicking gold finch. I +have seen a catbird on his way to a tree turn three somersaults, much +like those performed by a tumbler pigeon, after which he alighted upon +the bough. None of these acts seemed deliberately performed in front +of the females, but I have seen three or four killdeer parading in +most stately and precise manner, spreading their wings and fluffing +their feathers, performing a sublimated cup-and-cake walk amid a +circle of attracted females. + +Even our little English sparrow, as I have previously mentioned, +fluffs himself up and spreads his wings and prances around in front of +his presumably adoring ladylove. But the weirdest performance of this +sort I have ever seen is that shown by the male ostrich. When he +becomes excited, swaying his body from side to side, he sinks slowly +upon his knees, until his body touches the ground, his wings spread on +either side and the feathers fluffed up so as to show every exquisite +plume in all its splendid beauty. The long neck is laid back until the +head, which is doubled sharply forward, is pressed almost against the +back, and in this strange position he sways from side to side, +apparently utterly oblivious, for a time, of everything. After about a +minute of this performance, he seems slowly to come to himself and +rise again to his feet. Now he is particularly likely to make vicious +attack upon anything within reach. + +It is not only necessary that the animal should be able to attract a +mate. There may be more than one claimant for the damsel's affection. +In many animals we see provisions whereby the male may effectively +deal with his rivals. This is especially likely to be the case if the +animal be a polygamist. In every species there are produced about as +many males as females. If the polygamous habit leads one male to +gather about him a group of females, with whom he mates, it is evident +that he is displacing an equal number of rivals, and they are not +willingly displaced. Accordingly we find that polygamy is usually +accompanied by a belligerent disposition on the part of the males. In +our ordinary barnyard fowl this trait is very evident. The rooster not +only domineers over the hens, not only struts about among them in +stately fashion and gives vent to his feelings by his sonorous voice, +he must also drive away from the neighborhood any rivals for the +affections of his wives. Hence the rooster attacks upon sight the +neighboring rooster, and battles with him to his entire discomfiture +and sometimes to the death. + +Among the members of the deer family this particular phase of the +relation between the sexes has produced in the males, and only very +rarely in the females, the magnificent branching horns. These are +intended not so much as a protection against the enemy as for an +offensive weapon in the battle for the mates. + +Beautiful and stately as are these magnificent horns, they last only +for a part of the year. We begin to understand their meaning. When the +wolf is hungriest, toward the close of the bitter winter, the deer is +without horns. When the time for mating comes, the deer within a few +weeks grows his horns, which at first are covered with a plushlike +coating, known as velvet. After a while this dries and he rubs his +horns against the trees until they are clean and smooth. Now he is +ready for the battle royal. + +In the case of the fur seals polygamy has carried its specialization +of the males to a remarkable extent. The bull seals are several times +as large as the cows, and are provided with terrific canine teeth. +With these they battle with a violence that very often results in the +death of one of the combatants. A successful bull seal who has +gathered about him a cluster of seal cows is seamed and scarred with +the marks of his annual combats. + +One more type of adaptation can be profitably considered. Animals have +developed many devices which serve for the protection of their young. +The wonderful silk spun by the spider was evidently primarily intended +to serve as a covering for the eggs. Probably all of our spiders agree +in using the silk for this purpose. Many of them employ it for +practically no other, though there are half a dozen different uses to +which different spiders may put their silk. Under these conditions we +have a right to infer that silk was primarily developed as a coating +for the eggs. In the case of some of our spiders a little fluffy mass +of silk covers the egg, while a firmly woven sheet of silk covers both +egg mass and fluff, holding it flat against a wall or the trunk of a +tree. In some of the higher spiders, notably our bank spiders, the +silken covering becomes an effective cocoon, spherical in shape, with +a little opening at the top like the neck of a small bottle. The egg +cocoon is woven in a mass of tangled silk between the branches of some +tough weed which will be sure to outlast the winter. Into the egg +cocoon the spider may place one thousand or more eggs. Having thus +provided her children with a snug winter home, the spider dies. When +spring comes with the warm rays of the sun, the eggs hatch and the +cocoon becomes a creeping mass of minute spiders. At the time these +spiders appear there is nothing for them to eat. The obvious way out +of this difficulty is taken. At once there begins a progressive party. +Spider fights with spider, and the prize in each conflict is the body +of the victim, which is promptly eaten. The winners in the first round +pair off again, and a little later, as hunger drives them, another set +of combats comes on, resulting in another halving of the number of +spiders in the cocoon. This process continues until not more than +one-tenth of the original number of spiders remains. By this time they +have gained sufficient strength of leg and jaw, and sufficient +dexterity in the use of both, to make it safe for them to venture out +and try their fortunes among the accidents of a strenuous world. There +can be little doubt after this long process has worked its final +results which tenth remains. Chance plays but small part in this +game. It is the fittest that survive. When this procedure goes on +generation after generation, the result must necessarily be that the +spiders grow fitter and fitter for their work. This method is hard on +the little spider, but it makes good spiders. + +Most insects die before their eggs hatch; accordingly they can pay no +attention to their own children. Whatever arrangements are provided +for the safety and strength of these offspring must be provided before +they appear. About the only care the majority of insects take in this +direction is to see that the eggs are placed where the young shall +find food as soon as they emerge. Insects' eggs are very small, and as +a consequence the creatures which emerge from them are likewise +exceedingly minute. As a result they cannot be expected to hunt far +for their food. Different insects use different devices by which to +overcome this difficulty. The katydid, for instance, must die with the +approach of fall. Her children will not appear until the following +year. Her food consists of leaves, but to lay the eggs in such a +situation would be a fatal process, because the leaf will drop off +before the eggs hatch. Accordingly, the katydid lays its shield-shaped +eggs in a double row near the end of a young twig. Next year when the +weather is sufficiently warm to hatch katydids, it is also warm enough +to force the buds on the end of the twigs. When the katydids arrive +their jaws are young and tender, but so are the leaves upon which they +are born. Hence there is little difficulty on the part of the young +katydids in finding an abundance of food. By the time the leaves have +grown tougher, the katydid's jaws are stronger, and the leaves will +still serve as food. + +Everyone who is at all familiar with country life and gardening is +familiar with what is called the potato or tomato worm. It is a long, +green, smooth, caterpillar, as long and as fat as your finger and +provided with a horn upon his tail. The gardener may not know that +after a while this creature will burrow into the ground, and there +change into an oblong brown mass with a sort of a pitcher handle at +one side. Next year this pupa will split down the back, and from out +of the brown case will come a hawk-moth, which soon will fly with +rapidly quivering wings and feast upon the nectar of our moon flowers +or on that of the "Jimson" weed. Those who have cleaned these pests +from the potato or tomato vines will often have noticed one of them +covered with what look almost like grains of rice. This appearance +reveals an interesting story. Some time earlier an insect that looked +very much like a dainty wasp with a rather long sting in its tail +hovered over the caterpillar. This is the ichneumon fly. Eventually +lighting upon the caterpillar's back, it punctured the skin with its +sting, and deposited eggs within the caterpillar's body. These eggs +soon hatched and the little grubs worked their way through the body of +its host. The infested victim feeds upon leaves and fills itself with +rich food. These parasites eat the food, and, try as it may, the +caterpillar does not succeed in getting fat. After the grubs have +gotten their full growth, each of them eats its way through a little +hole to the outside of the caterpillar's body. Here it spins around +itself a little white case, and looks like a rice grain. As the +caterpillar moves about, these seeming rice grains are rubbed off and +fall to the ground. Next year there will come up new ichneumon flies +to sting fresh caterpillars and repeat the entire process. + +Another remarkable provision for the young on the part of insects is +seen in the behavior of the big sphex wasp, known as the cicada +killer. The cicada, it will be remembered, is what is commonly called +a locust. The cicada killer is a magnificent big wasp, whose body is +nearly an inch long, banded with black and yellow, while the wings are +colored a smoky brown. This muscular wasp digs a long tunnel eight or +ten inches deep, which ends in a slightly larger room. Having provided +the location, he now sallies forth in search of the cicada. The heavy +song of the male probably serves as a guide to the wasp in case of +scarcity of cicadas, but the killer has apparently little difficulty +in finding his prey. The wasp pounces upon the insect, and in spite of +its strength and the thrashing of its vigorous wings punctures it with +his sting again and again. The poison of the sting entering into the +nerve centers gradually paralyzes, but usually does not kill, the +cicada. Now the killer carries its prey home, pushes it to the bottom +of the tunnel and deposits upon it a single egg. The wasp closes up +the hole and leaves the place. When the egg hatches and the grub of +the wasp emerges, it finds a big cicada just at hand, upon which it +feeds. By the time the cicada is completely devoured, the wasp grub +has obtained its full growth. After a short period of development a +new sphex wasp is ready to work its way out of the tunnel, find a +mate, dig a hole, and safely provide for its own children. + +Still more remarkable adaptations for the care of the young appear +among the birds. Here the eggs are not to be deserted, but are to be +cared for until the young appear. These again must have attention +until such time as they are quite able to take care of themselves. The +birds are warm-blooded animals, and even their young, while they are +developing in the egg, are warm-blooded. Consequently the temperature +of the egg must be maintained evenly and uniformly, or there will be +no development. + +The fish may drop its eggs carelessly upon the bottom of the stream. A +frog may deposit them in a mass of jelly and leave them forever. A +turtle may bury its eggs in a sand bank and abandon them to their +fate. The warm blood of the young bird demands more attention than +this. Accordingly, the parent bird has learned to make for itself some +sort of nest, in which the young may be kept properly warm until they +are developed. The ancestral bird, who was to be the progenitor of the +entire bird class, must have had some very simple method of providing +a place in which its eggs might be hatched. As the descendants of this +original bird have passed into new situations, the various lines have +taken upon themselves different shapes until we have the multiform +birds of to-day. The habits of the birds have also varied. Each has +adapted itself to the situation in which it found itself, and no +adaptation has been more varied and effective than the adjustment of +the nesting site. Nests are found upon the ground, in the bushes, on +the lower limbs, in the crotches of the trees, in the trunks of the +trees, upon their very summits, and on the tops of inaccessible crags. +To every sort of situation some bird has been enabled to adapt itself. +This has made it possible for very many more birds to thrive than +could have found a place in the world, had they all lived upon the +same plan. + +In the case of the bank swallow his nest may be a very simple +contrivance, consisting only of a tunnel running back into a bank, and +widening at the back. Some material that will soften the bed upon +which eggs are to be laid must be placed in this cavity. The whole +home is a very simple and crude affair. But little better is the +arrangement which the woodpecker calls a home. This has been cut into +the dry wood of a defective tree. No woodpecker can make his home in +absolutely solid sapwood. Hence the first labor of the woodpecker must +consist in finding a place in which it can dig. If there is an old +stump of a limb sticking up, the problem is readily solved. Such wood +has no sap in it, and is brittle enough to be easily dug out. But, if +there be no such stub, the woodpecker will find a suitable place in +most trees. At some time or other almost every tree loses a big limb. +When such accident occurs there will always be in the old trunk a +region through which sap once went to this limb. This region, deprived +of its function, goes completely dry, like the heartwood of the tree, +and it is into such material as this that the woodpecker succeeds in +drilling his well-protected home. + +As birds rise higher in the scale the nest-building becomes a more +complicated affair, and after a while we find a well-woven substantial +nest, through which even the air will not chill the eggs enough to +prevent their hatching, while the warmth is supplied by the mother's +body. It is often a matter of surprise to many people that a bird +should contrive to build a nest so exquisitely circular. The trick, +after all, is not quite so difficult as it looks. The robin gathers up +a few sticks and places them as the beginning of the platform. More +and more are brought and woven into each other, making a framework +altogether too big for the nest. Then mud is brought and plastered +inside of this. With the plastering of this mud the careful +circularity of the work begins. Every time a little material has been +added the robin sits down in the nest and revolves her body, in this +way shaping the interior much as the potter shapes a pot. In the case +of the artisan, it is the pot that revolves. In the case of the robin, +the bird itself revolves. The effect is the same in both cases--a +circular vessel is produced. A little lining added to the interior of +the nest softens it for the reception of the eggs. In this exquisite +home the robin lays her eggs, and sits upon them until they are +developed enough to hatch, and then feeds the young until they are old +enough to feed themselves. + +Far more remarkable than any of the devices thus far described are the +wonderful developments which have come in the class of animals known +as the mammals. Here the most wonderful protection is made for the +care and feeding of the young. But this is to be the subject of a +separate chapter. + +As long as we thought of each sort of animal as being a separate +species shaped in the beginning by the hands of the Creator, each of +these devices seemed to us a new manifestation of the Divine +Providence, whose fertile planning had conceived so many methods of +providing for his children. Unconsciously we thought of God acting as +man acted. Each animal seemed a purely separate invention purposely +designed for an especial place. Now we understand the plan in creation +better, and see that each animal has come from another not quite like +itself, some distance back, and this from still another. Our +admiration for these devices as they arise through evolution is no +less, but takes on another form. + + + + +CHAPTER VI + +LIFE IN THE PAST + + +Anyone who earnestly studies plants and animals as they exist in the +world to-day cannot help wondering how the earth began and where it +got its life. This is the true end and aim of geological study. The +history of man seems to run back into a far distant and gloomy past. +Except for the poetical account in Genesis and the traditions of +various peoples throughout the world, real history fades away into an +earlier time of which there are no written records. When the delvers +in the Mesopotamian plain talk to us of kingdoms running back through +seven or eight or nine thousand years, we seem to be getting back to +the beginnings of things. But seven or eight or nine thousand years +are as nothing in comparison with the age of the earth, which runs +back into a past so limitless that no man can safely assign any set +figure to it. In a recent paper, Dr. Walcott, of the Smithsonian +Institution, says that the antiquity of the earth must be measured not +in millions, for they are too short, nor hundreds of millions, for +this carries us too far, but must surely be measured in tens of +millions of years. + +When we attempt to study the past we find its various epochs unequally +clear to us. In human history only quite modern times are absolutely +clear. The history of the Middle Ages is distinct enough for us to +build for ourselves a picture of the time with reasonable hope of +gaining a correct view of the state of affairs. Back of this comes the +long stretch of the Dark Ages, in which here and there we have bright +spots, but it will perhaps long be impossible to portray clearly the +life of the people. Getting back to the Romans, things once more +become reasonably plain, as is true also in the case of Greek history. +Back of this stretches the Egyptian with fair precision, and, older +than it, the Babylonian and Chaldean. But these past three have not +left nearly so definite an account for us as did the later +civilizations of Greece and Rome. + +When we try to go back of these we must change our method of study +entirely. Writing is absent, and all we know of earlier men must be +inferred from a few pictures that were daubed on the rocks or carved +in ivory or bone, from tools made of stone or bone, from a few metal +or stone ornaments, or from the bones of the men themselves. Even so, +the history fades out without telling us its own beginnings. It is +quite as impossible for history to write its origins as it is for man, +from his own knowledge, to describe his birth. + +What is true of the human story is quite as true of that of the earth. +Recent steps are very plain. We may read them with considerable +confidence. As we go deeper into the rocks and find older fossils, the +evidence becomes less certain. The animals differed enough from those +of to-day for us to be less sure what they were like. As we keep on +moving backward through time, and downward through the rocks, we find, +after a while, strata in which there are evidences of life that +existed long ago, but in which these traces are so altered that it is +impossible to tell what sort of living things existed; we learn only +that they were alive. Going back still further, these fade out. There +is no knowing when the earth began; there is no knowing when life +began upon the earth. It is not meant that men have not wondered, even +reckoned carefully, as to how long ago each of these events occurred. +Many speculations have proved entirely useless, a few remain as yet +neither confirmed nor disproved, and of such we shall speak. + +For the last hundred years the theory of the earth's origin suggested +by the Marquis Pierre Simon De La Place, of France, near the end of +the eighteenth century, has held almost undisputed sway among men who +were willing to consider the question as open to human solution. This +theory is known as La Place's Nebular Hypothesis. When men began to +study the heavenly bodies with the newly invented telescope, new ideas +naturally sprang up. Among the objects which the glass disclosed were +the nebulae, which are great clouds of fire mist, glowing masses of +gas. They are scarcely visible to the naked eye, but are among the +most interesting objects in the heavens when seen through a telescope. +The other suggestive heavenly body was our sister planet, Saturn. +Besides having a full complement of moons, Saturn has around it, as +distant as we would expect moons to be, three great rings. These look +very much as if one's hat, with an enormously wide brim, should have +the connection between the rim and the hat broken out completely, but +the rim should still float around the hat without touching it and +should steadily revolve as it stood there. The rings of Saturn are not +solid like the suggested hat rim. They are evidently made up of a +great number of very small particles, each moving around the center of +Saturn. But the great cloud of them is spread out flat. At the +distance which Saturn is from the earth they look as if they made a +solid sheet. Furthermore, they do not form, as it were, one continuous +hat rim, but it is as if the rim were broken into three circular +sections, each bigger than the one inside it and separated from the +next by an area nearly as wide as the ring itself. + +With such material in the heavens to guide him, La Place suggested +that the sun had once been an enormous fire mist scattered over an +area billions of miles in diameter. This gaseous material, by the +attraction of its particles for each other, began to condense and +contract. When the plug is pulled from a washbasin the particles of +water, in moving toward the center, in order to get out of the basin, +invariably set up a rotary motion. As the particles of this diffused +nebula began to gather together they, too, gave to the mass a rotary +movement. This grew more and more rapid, with greater contraction, +until the particles on the outer edge of the rotating mass had just so +much speed that the least bit more would make them tend to fly off as +mud would fly from a revolving wheel. When this point was reached +there was a balance of forces which made the outermost portion remain +as a ring while the rest contracted away from it, leaving it behind. + +It was La Place's idea that this process had repeated itself, and ring +after ring had been left behind. Finally the sun condensed and grew +into a ball, occupying the center of the system. At varying distances +from it were to be found either rings or planets which had been formed +out of such rings. For La Place suggested that in a ring like this +the material could not be quite evenly distributed. While every +particle in the ring kept revolving around the sun, those in front of +the densest part were slowly held back by the attraction of the +thicker portion, while those behind it in rotation had their speed +hastened until finally all the material in the ring had collected at +one spot and a new planet was born. La Place believed that these +planets formed their moons in exactly the same way, and that Saturn +was simply a planet not all of whose moons had yet been formed. He +believed that this happy accident served to tell us how the universe +had been created. + +Of course, so detailed a theory concerning anything of which we know +so little has always had much ridicule thrown upon it, and yet no +truly competing theory has been proposed until very recent times. + +Within a few years a Planetesimal Theory has been announced, and is +gaining considerable prominence, although it is too early yet to say +whether it will supersede La Place's idea. In this theory, also, the +suggestion comes from the heavenly bodies. With the increasing study +of the nebulae, many forms of these interesting bodies have been +discovered. A very common type consists of a great coherent central +mass, with two or more arms extending from opposite sides in the form +of a spiral. This is as if gaseous revolving nebulae had come into +comparatively close proximity to a passing body. The visitor, by its +attraction, drew from the nebula a wisp of gas. The revolving motion +of the nebula gave to the attracted arm the spiral form. + +These twisted arms are not equally dense throughout, but have +thickened knots here and there in their course. The Planetesimal +Theory suggests that these thickened knots are embryo planets and the +central portion of the nebulae an embryo sun. After all the material in +such a body has condensed either around the knots or about the central +mass a new solar system will be complete. As before stated, neither of +these theories can be said to be demonstrated. Each of them has points +in its favor and each has its difficulties. It is pleasant to know +what men have clearly thought concerning such questions, but for a man +not a trained geologist neither will carry much conviction. He will +still rest with his own early conclusion that whichever shall prove to +be true, for him his old formula is still valid, "in the beginning God +made the heavens and the earth." He will no longer think of God as +having shaped the balls with his own hand and thrown them into space; +he will no longer dream that it all occurred within a week not more +than six thousand years ago; but still to him will come the reverent +conviction that, whatever the plan by which it was accomplished, it +was still God's plan and God carried it out. + +Now that we have tried to stretch our imagination back to the origin +of our globe, the question not unnaturally comes to our mind, how long +ago did all this happen? Is there any possible means of telling when +the history of the earth began? All such attempts lead either to +indefinite or to uncertain conclusions. Each man who essays the +problem approaches it from a different side and ends with a different +result. But no matter what the method of approach, all are agreed on +at least one point, the enormous length of time, as counted in years, +through which the earth has lasted. + +One great mathematician worked on the basis of the rate of the present +cooling of the earth. Counting backward to the time when the earth's +surface must have been hotter, according to La Place's idea, he +decided that our globe has been cool enough for the existence of life +upon it for a period of somewhere in the neighborhood of one hundred +million years. Those who try to study the rate at which mud is being +deposited in our bays and at the mouth of our rivers, and who hence +try to deduce how long it has taken to produce the thickness of all +the stratified rock we know, arrive at a figure larger, rather than +smaller, than that mentioned above. The same is true of those who try +to count the age of the earth by the rate at which the present rivers +are carrying away their river basins, and hence who calculate how long +it has taken the rivers of the globe to wash away all the rocks which +it is quite clear have been carried out. Still others have attempted +to solve the problem by seeing how much salt the rivers are carrying +into the sea, and consequently how long it must have taken the sea to +become as salt as it is. A very late attempt has been based on the +alteration in the minerals that show radio-activity. Conservative +estimates, based on all of these, would give us a figure on which we +must not count with any exactness, but which will serve at least to +mark the present trend of opinion. We may put this figure at one +hundred millions of years. + +The following table gives us the names of the periods into which the +geologist has divided the past history of the earth. The first column +gives a simple name, which, in each case, is a translation of the +technical name the geologist gives to the era. This technical name is +also given in parenthesis. The second column shows the number of years +ago at which this period may be placed, while the third column gives a +series of names most of which are in use in geology and which are +intended to indicate the stage of advancement of the higher animals in +that particular period. Some of these names are perhaps giving way to +later terms, but all of them will be understood by any geologist. +Most of them will serve to keep very clearly before the mind of the +ungeological the period which he is studying. Like all such tables, +this must be read from the bottom up. This arrangement is used because +the oldest rocks in the series are naturally at the bottom and the +newest rocks are on the top, though occasionally a region is +sufficiently upset partly to reverse the order. + + TABLE OF GEOLOGICAL TIMES + + ------------+------------------------+--------------------------- + | MILLIONS OF YEARS AGO | STAGES OF ANIMAL + ERAS | (VERY UNCERTAIN) | DEVELOPMENT + ------------+------------------------+--------------------------- + | | Age of Man + Recent Life | | (Quaternary) + (Cenozoic) | 0 to 5 | Age of Mammals + | | (Tertiary) + ------------+------------------------+--------------------------- + Middle Life | | + (Mesozoic) | 5 to 10 | Age of Reptiles + ------------+------------------------+--------------------------- + | | Age of Amphibians + | | (Carboniferous) + Ancient Life| | Age of Fishes + (Palaeozoic)| 10 to 25 | (Devonian) + | | Age of Invertebrates + | | (Silurian and Cambrian) + ------------+------------------------+--------------------------- + Dawn Life | | Earliest Animals and + (Eozoic) | 25 to 50 | Plants + ------------+------------------------+--------------------------- + +Having seen what the scientist supposes to be the method of formation +of the earth itself, it will be interesting next to consider what the +biologist surmises as to the origin of the life upon the earth. Here +again two explanations hold. The one, and distinctly the older of the +two, says that at some time in the far distant past, under conditions +which are rarely if ever duplicated, out of the lifeless material of +the globe were produced simple and low forms of life. These could not +properly be called either animal or plant, but partook somewhat of the +nature of both. Of this there is at present no evidence whatever. The +only reason we have for suggesting it is that, if we understand the +past conditions on the earth, there was a time when life was +impossible. Now we find life. Hence it must have arisen. This of +itself, of course, furnishes no proof, but leads us to try to imagine +how the transition might have come about. Every scientist who believes +in this form of origin holds that if the exact conditions are repeated +the result will occur once more. He may believe that no such +repetition is possible, but he is confident that, if it could be, life +would arise again from lifeless matter. + +This process of life arising from matter that is not alive is known as +Spontaneous Generation. Two hundred years ago it was supposed to occur +frequently. It was common belief that the beautiful pickerel weed +which borders our Northern lakes, after freezing, went into a sort of +protoplasmic slime out of which pickerel were produced. The eelgrass +of the river was supposed to yield eels in a similar fashion. The dead +bodies of animals were supposed to turn into maggots. Such crude ideas +of spontaneous generation are no longer possible. The whole science of +bacteriology absolutely presupposes the impossibility of spontaneous +generation in the flasks and test tubes of the laboratory. One or two +men of otherwise good standing in science still maintain that they are +getting new life in their own test tubes, but they fail utterly to +persuade the scientific world. I think it is a fair statement of the +position of science to-day to say that there is no evidence whatever +of spontaneous generation, excepting the presence of life upon the +globe. + +Not all has been said, however, on this question. The chemist is +learning in the laboratory to produce many substances which, until +very recent times, were produced only in the bodies of animals or +plants. Dye-stuffs were originally gotten almost entirely from animal +or plant material. At present the great majority of them are made in +the laboratory, and in not a few cases they not only imitate the color +of the older material, but actually have identically the same +composition and constitution. The laboratory-made material is exactly +like that made by the animals or the plants. + +The same is true with regard to a large number of the fruit flavors. +These are due to the presence of ethereal oils in the plant, and their +exact counterparts can now be produced in the laboratory, and can +serve every purpose of the fruit flavor itself. Alcohol has been +produced artificially, and alcohols, which nature never dreamed of +making, so far as we can tell, but which are made on her plan, are +manufactured by the chemist. Last of all, sugar has recently been +built up by the chemist, though the method at present is so expensive +that it cannot possibly compete with the production of the commodity +from the cane and the beet. As in the case of alcohol, all the sugars +that nature makes can now be made artificially, and others of the same +general plan which she seems not to have as yet devised can be +produced within the laboratory. + +Attempts have been made to manufacture proteids, but these have as yet +eluded the efforts of the chemist. He is beginning, however, to come +nearer understanding their composition, and when he once clearly +comprehends that he may be able to reproduce them. + +One of the German chemists is convinced that the nuclein in the +nucleus of the cell is not a very complicated compound. Under such +conditions it is not a matter of surprise that the physiological +chemist should be constantly dreaming that he may at some time produce +living matter in the laboratory. To the ordinary mind it scarcely +seems possible. We are so entirely sure that life is not amenable to +physics or chemistry that we can hardly conceive of the possibility of +its originating out of matter in the test tube. If it does so come, +and when it does so come, this will not prove that life is a less +noble and less wonderful thing than we thought. It will only prove +that chemistry and physics are more noble and more wonderful than we +dreamed. + +There is another way of approaching this life problem, though it seems +to be rather a begging of the question than a solution of it. Of +recent years it has been discovered that even the very low +temperatures obtained by evaporating liquid air, say three hundred +degrees below zero, Fahrenheit, do not kill seeds or spores of mold. +The space between the planets is undoubtedly extremely cold. We have +always supposed it to be entirely too cold for life to exist in it. +But we laid little stress on the fact because we had no thought of any +possible life existing there. But the discovery that seeds and spores +can live uninjured through extreme cold has led to an interesting +suggestion. This is that when the earth became adapted to the presence +of life it was infected by germs transported on meteors from some +other system. According to this theory, organic dust through space is +ready to infect any planet which offers the conditions under which +life may arise. Of course this theory does not explain the origin of +life. It pushes back that origin a little farther or supposes that +life is as old as matter itself. Again we may leave to the scientist +the discussion and the elaboration of this or any other theory he may +promulgate concerning the origin of life. When he has established +clearly the process and can produce life we will accept his +explanation; meanwhile, we will always be interested in his attempts +to solve the problem, but still our simple formula, "in the beginning +God," serves our present needs and will satisfy us better than any as +yet unverified hypothesis. + +When we find through scientific investigation how life arises we will +simply know how God created it in the beginning. + +The next step in the understanding of early life is to study under the +microscope the simplest forms which we can find in existence to-day. +This, while far easier of execution than the problems which we have +thus far considered, is still not without serious difficulties. But +every day brings us nearer to the understanding of the structure of +living things. Life the scientist cannot see. All he can study is +living matter. Whether life can exist separate from living things is a +problem outside the range of his, at least present, possibilities. +Therefore, concerning it he has no answer whatever to give. But when +we come to study living things we find that all life is associated +with protoplasm. This apparently foamy, jellylike, transparent +material is the only living substance in all the world. Animals and +plants are larger or smaller collections of the little masses of +protoplasm which we know as cells. The lowest animals are each made up +of but a single cell. This consists of a small mass of protoplasm +surrounded almost always by a thicker skin or covering, known as the +cell wall and enclosing a complicated kernel known as the nucleus. The +protoplasm seems to be the living substance itself. The cell wall is +not a simple dead scum on the outside of the protoplasm, but is itself +able to do certain things which can only, so far as we know, be done +by living substances. For instance, of two materials dissolved in the +water in which the cell floats, the wall may permit one to soak into +the animal and keep the other out. The one allowed to enter will +usually be found good to be used for food by the cell. The nucleus +seems to store within itself the record of its past history and thus +enable the cell to do in the future what its ancestors did in the +past. + +Such simple cells can exhibit in very low form all the activities the +higher animals show in much more elaborate development. A one-celled +animal can move about, can recognize the proximity of food, can engulf +its food and digest it, can build up its own substance out of the +digested food, can absorb oxygen, can use this oxygen in the burning +of its own substance to produce its own activities, can act in +response to sensation gained from outside, can throw off its waste +matter produced by its own activities, and can grow. When the proper +time comes its nucleus can split in two, the cell itself enclosing the +nucleus can separate into two cells, each of which can grow to the +size of the parent cell and repeat its life. This is as simple an +animal as we have yet discovered. Every kitchen drain swarms with such +creatures. On a summer day the stagnant pools are full of them. The +simplest microscope will show them clearly. This is life in its lowest +terms with which we are acquainted. With such life, it seems to us, +the animal and plant world must have started their existence, when +first the earth began to teem with living matter. + +If, then, we may form any judgment concerning the first living things +upon the globe by considering the simplest creatures that live here +to-day, certain facts seem clear. In the first place, life began in +the water, and for a long time was only to be found in the water. +Single cells are so small and dry out so easily that it is necessary +to their existence that they should be kept entirely moist by the +presence of water all about them. It is true many of them will stand +drying, but while they are thus dried they can scarcely be said to be +much more than just alive. They are utterly inactive, or, as we say, +they are dormant. In such conditions they become covered with a tough +skin, almost a shell, and their protoplasm is itself nearly dry. Under +these circumstances the life processes hardly continue at all. The +protozoa, as these small animals are called, tolerate drought for a +time; but they only live, in any sense worth calling living, when +water is abundant and is neither very warm nor very cold. It is safe +to say that the early life of the world formed in the oceans of the +time. So absolutely is the habit fixed upon cells of protoplasm that +even to-day the activities of the cells of higher animals depend upon +the presence of moisture. The cells of our own bodies are to-day +living, as it were, in an ocean. Everyone can remember far enough back +to recall some time at which a tear slipped from his own eye onto his +own tongue; we know our tears are salt. The tongue has tasted, +undoubtedly, the perspiration from the lip on more than one summer +day; this perspiration tasted as salt as the tear itself. The lymph +that constitutes the "water" of a so-called "water blister" is also +salty, and even the little blood one gets into his mouth in trying +nature's method of stanching the flow from a cut finger gives the +impression that it contains a little salt. Every fluid of the body is +salty, and every cell of the body is bathed in salt water. It is too +long since the ancestors of our cells swam in the seas of the Eozoic +time for us to assert with any positiveness that the ancestral habit +is responsible for this trait in the descendants. Sure it is that +to-day our cells, like their ancestors of old, live in water, and this +water is slightly salty--as were probably the Archaean seas. + +The geologist tries as best he may to build up the geography of the +earth in the past. He endeavors to judge from the rocks as he now +finds them, where the seas, the bays, the dry land, and the mountains +of earlier geological times lay. The present aspect of the earth is +very recent, and earlier ages must have shown an entirely different +distribution of land and water. The North American continent was +certainly very much smaller than it is now. The first known lands lay +close to the Atlantic seaboard and probably extended out into the +water some distance beyond the present shoreline. The stretch of +continent was narrow, and grew narrower as it went southward. In what +is now the Canadian district, a considerable expanse probably existed +in very early times. Then a great internal sea, shallower than the +Atlantic, stretched its unbroken sheet over almost the entire area now +occupied by the United States, while only a comparatively small hump +of earth, ending in a narrower strip, lay where the great Western +plateau now rears its enormous bulk. + +A large portion of the history of the North American continent, with +its developing animals and plants, is tied up with the gradual +shrinkage of this interior sea. Slowly across the Canadian district, +the Eastern and Western lands became connected with each other, while +the waters progressively were pushed down the continent, which was +steadily growing from the east and from the north, though less slowly +from the west, into this internal sea. To-day only the Gulf of Mexico +remains as evidence of the broad stretch that once extended through to +the Arctic Ocean and west beyond the present position of the Rocky +Mountains. + +How this great Eastern backbone of the continent was produced, what +sort of animals lived while these rocks were being formed, or whether +this preceded entirely the existence of life upon the earth, no man +to-day may surely say. In the oldest of the rocks there are beds of +graphite, from which lead pencils are made. This substance is believed +by the geologists to be, like coal, the remains of vegetable life. But +these early rocks have been so heated and baked, so twisted and bent, +that whatever forms of life they once held are now obliterated, or so +altered as to give us no idea of what may have been their character. + +So far as anyone can now see, this past history is wiped out forever +and it will be impossible for men ever to demonstrate the character of +this early life. Speculations, more or less certain, will arise. They +may, after a while, seem so clear as to receive the acceptance of the +scientific mind. Yet the truth remains that the early history of the +earth, so far as animals and plants are concerned, is probably lost +forever. + +The most striking feature concerning the earliest layers of rocks in +which good fossils are found abundantly is the complexity of the life. +With the exception of the backboned animals, every important branch of +the animal kingdom is represented, and it is just possible that we +have even earlier forms of the vertebrates themselves. This, to the +evolutionist, is very disconcerting. To find the great groups all well +developed at least twenty-five million years ago and to find only +fossils built on the same lines since almost nonplusses him. When the +geologist tells him what an enormous length of time preceded the rocks +in which he finds these fossils and how absolutely these earlier +strata have been altered by the later geological activities he easily +understands why it is impossible to find fossils in them. As a +consequence, the evolutionist is forced to believe that all the +earliest animals have left no clear traces behind them. Life as he +first surely knows it is already extremely varied and quite well +developed in some of its groups. The early animals were as well +adapted to the times in which they lived as are the great majority of +the animals of to-day. The reader must not infer this to mean that +the animals of those days were like our present animals. They were +not. No one traveling in a far country could find there animals as +strange to him as would be those of the earlier stratified rocks. In +these there were no fishes as we know them to-day, not a single member +of the frog and salamander class, not a reptile, not a bird, not a +mammal, and probably no air-living insects. It is highly doubtful +whether there was any animal living upon the land and breathing the +air twenty-five million years ago. + +We start our study, then, at the period known as the Palaeozoic era, +the era of the ancient life of the globe, beginning twenty-five +million and ending ten million years ago. The first of the three +sections into which this period of life is divided is known as the +Silurian age, the age of invertebrates. The word invertebrate is an +unscientific but convenient term under which we embrace all the +animals below those having backbones. This period is called the age of +invertebrates because, although there is an enormous wealth of animal +and plant life in the Silurian, there are no backboned animals except +the lowest kinds of fishes. It was supposed for a long time that even +fishes were absent. Now we know they existed, but they were small and +inconspicuous. In this period corals were wonderfully abundant, +particularly in the great internal sea which spread over what is now +known as the Mississippi Valley. Everywhere over this region must have +grown in the shallow water great numbers of creatures called crinoids +or stone lilies. They were attached to the bottom by slender stems, +sometimes many feet long. These stems are jointed, and when they +became fossilized the sections were apt to separate, with the result +that over a wide area in the Mississippi Valley it is very common to +find these little segments which look not unlike checkers. At the end +of the stem was a rounded head, with a mouth at the top, and around +the mouth were branched, feathery arms. The creatures must have been +exquisitely beautiful, but they have completely disappeared from the +face of the earth, with the exception of a very few, found in the +obscurity of the almost fathomless depths of the great ocean. Here +they remain as peculiar relics, only preserved by the unvarying +conditions in the deep sea from the extinction that has met their +sisters. + +Those who are familiar with our seacoast will know an interesting +creature known as the horseshoe crab, or king crab, though in reality +it is not a crab at all. It is rather more nearly related to the +spiders than the crabs, though no one but a technical zooelogist could +possibly associate them together. The ancestors of these king crabs +were the finest and best developed animals in this early Palaeozoic +time. These creatures had bodies jointed like the tail of a lobster. +They were wide and flat, instead of narrow and rounded like a lobster, +and each joint of the body was highest in the middle and distinctly +lower at the two sides, thus forming three regions along their backs. +This structure gives to these creatures the name of trilobites. These +animals were the kings of the early ocean. They had an interesting +habit of curling up nose to tail before they died, and, as a result, a +large proportion of all the trilobite fossils we find are curled in +this peculiar manner. + +After these forms the most abundant fossils we find in Silurian times +were creatures that at first sight looked as if they might be related +to the clams. These are known as lampshells, because one shell +projects beyond the other and curls up at the tip so as to resemble +the clay lamps which are dug out of old Roman towns. The lampshells +also have nearly disappeared in modern times. Simple creatures +belonging with our present crab and snail had begun to make their +appearance, but they were not as abundant as we find them later on. + +The third group of the mollusks to which the nautilus and squid of +to-day belong is very abundantly represented in the Silurian by +fossils with coiled-up shells. As for the plant life of the time, it +is exceedingly difficult to say much about it. There must have been +nothing but marine plants, and these must have been on the general +line of the seaweeds. Little can be definitely said concerning them. + +The next period of the Palaeozoic is known as the Devonian age, or the +age of fishes. Now the backboned animals first make their clear and +unmistakable appearance. There are remains in the Silurian which show +that there must have been a few fishes at that time. The Devonian is +so full of them and they are so well developed and so diversified that +this period is definitely known as the "age of fishes." They do not +closely resemble the fishes of to-day, but anyone would recognize most +of them for what they are. Their bodies were covered, not so much with +scales as with heavy plates, often arranged like tiles, those on the +forward half of the animal being often larger than those surrounding +the rest of the body. The creature was encased, as it were, in armor. +These were the rulers of the Devonian seas. The land, as yet, was +probably nearly without animal life, the creatures thus far being +almost confined to the water. A few insects make their appearance and +a few thousand-leggers are running around among the lowly plants; a +few spider-like animals have arisen; there are a few snails that have +left the water and taken to the land. Altogether only the dawn of a +land fauna is to be noticed. In the Devonian the plants are creeping +up upon the ground. Ferns are growing about everywhere, though they +are not exactly our ferns, but are rather a sort of intermediate form +between these and the present seed plants. + +Now comes an entire change in the history of the world. By some means +a rise in the bottom seems to have cut off a great part of the +internal sea from the outer ocean and to have converted it into a +widespread shallow bay, much like the sounds which lie back of the +islands that line the Atlantic Coast from New Jersey to Florida. Just +as this coastal region to-day is covered with salt marshes, so the +whole internal sea of the Carboniferous period was converted into a +great swamp. Sometimes an oscillation of the crust of the earth +brought this marsh above the surface of the sea and a luxuriant growth +of plants spread over it. Then a sinking of the bottom allowed the mud +and sand to wash down the shores, and spread out over the marsh, and +enclose the muck of the marsh under a layer of sand or clay. Another +lift of the bottom would start the swamp growing once more, and a +series of alternations between marsh land and sound seems to have +followed. The plants of this period are not the plants of to-day, +though we still have some very degenerate representatives of them. The +common horse-tail, with its angular, slender, leaflike branches and +its club-shaped spore-bearing body, is a modern degenerate descendant +of the treelike calamites of the Carboniferous forest. A creeping +evergreen, known by the name of clubmoss, is in like manner the modern +degenerate remnant of the scalestem and sealstem, which were the great +trees of the forests of the coal period. + +All over the surface of the marsh, between these big trees, grew the +ferns. While the coal itself was formed generally from the scalestems +and sealstems, the most common fossils found in the shales that lie +upon the coal beds are the ferns which covered the surface of the +marsh. + +It is believed by many geologists that this great luxuriant forest +points to a time when the climate was far warmer than it is to-day, +when the air was moist and heavily laden with carbon dioxide, and when +a great mass of clouds practically enveloped the earth. In this way +only do most geologists account for the enormous wealth of vegetation +in the Carboniferous period and for the abundance of plants up to the +Arctic Ocean, of the kinds that now grow chiefly in the tropics. But +of recent years a few geologists point to the fact that the peat bogs +of to-day, which seem to be the beginnings of future coal deposits, +are found almost entirely in cold countries. Hence it is a serious +matter to attempt to describe the climate of any part of the +Palaeozoic era. Certainly of the climate earlier than the Carboniferous +it is very risky to say anything definite. + +The forests of the coal period seem actually to have cleared the air; +at least now we begin to find creatures related to our salamanders and +frogs moving about among the stumps of the marshes. These amphibians +are evidently the descendants of some of the fishes of the Devonian +times. Among these fishes were some which bear a great resemblance to +a few found in South America, in Africa and Australia to-day, and +which we know as lungfish. Anyone who has cleaned our fresh water +fishes in preparation for the table will remember that inside of them +there is a long slender bladder filled with air. This bladder assists +in making the fish light, hence making it easier for it to support +itself in the water. In certain swampy regions these lungfish swim +freely in the water of the marshes. When the dry season comes, +however, the water evaporates, draining the marshes completely. This +would prove the death of most fishes. The lungfish have a curious +habit which keeps them over the dry season. They cover themselves with +a coat of mud, inside of which there is a lining of slime produced +from their bodies. In such cocoon-like cases they survive the drought. +The means by which they breathe during this dry season is +interesting. The swim-bladder which we have just described in other +fishes is, with this lungfish, peculiarly spongy in its walls, +presenting a large surface full of blood vessels which absorb the air +on the inside of the bladder. This air the fish changes with moderate +frequency, the result being that the swim-bladder serves him exactly +as the lung serves a higher animal. To this fact he owes his name of +lungfish. + +We sometimes gain much light concerning the past history of any +particular form of animal by studying the development of that animal +in the egg, or, in the case of the mammals, before birth. It is an +interesting fact that when the lung begins to form in the embryo it +starts as a simple sac which is an offspring from the gullet, and +occupies the position of the swim-bladder of the fish. This sac later +divides into two, and develops into the lungs of the animal. This +assures the zooelogist that the origin of the lungs in the higher +animals is found in the swim-bladder of the so-called lungfish. In +this Silurian time certain of these lungfish were perhaps trapped in +the basin in the marsh by the uplifting of the border. The waters +becoming progressively shallower and more crowded, these fishes took +to the land, their fins developing into awkward limbs which slowly +became more perfect. + +To state the fact in this simple fashion is to make it seem far less +probable than is really the case. The simple forms of the life of +lowly creatures, as well as the simple character of the legs and feet +in the salamander class, make the explanation not so unlikely as would +at first sight appear. Suffice it to say that the scientist now +believes that out of the lungfish of the Devonian came the amphibians +of the Carboniferous period. + +At the end of the coal period came the greatest change the face of the +globe had seen for many millions of years. Slowly the continent rose +on both sides of the old interior sea. A great plateau formed in the +region of the Alleghenies and another in the western district, though +this latter uplift was to be completely washed away, and later to rise +again into the Rocky Mountains and the Sierras. With the uplift at the +edges of the continent came a steady rise of the internal marshes, +until what had previously been swamp land became progressively first +dry land and, in the western part, even desert, in that respect being +somewhat like what it is now. + +The amphibians of to-day (animals like the salamander and frog) all +lay their eggs in the water and their young have a tadpole stage. This +doubtless was true of the amphibians of the coal period. With the +beginning of the Mesozoic, or "middle life" period, a change and a +progression comes over the animal world. The tadpole life of the frog +is a rather lengthened one, while the toad has learned to crowd its +tadpole life within a few weeks. It would seem as if, in the earlier +times of the Mesozoic, this same change of habit had been going on. +With the drying up of the swamp, some of the amphibians crowded their +tadpole stage further and further back, until it was completely +accomplished before their young left the egg. An examination of the +development of the reptile in the egg will show a stage very similar +to the fish and to the amphibians, but this is all experienced before +the reptile emerges from the egg. The reptilian egg, unlike that of +the frog, is covered with a shell, packed away under the surface of +the ground, and left to its own fate. If, as most geologists believe, +the climate of the Mesozoic was distinctly warm, this habit of the +parent of forsaking the egg was not a serious matter. However the +creatures arose, it is certain that in this Mesozoic age reptiles +roamed the forests, swam the seas, and even flew in the air. Probably +at no other time in the earth's history has any one class of animals +so completely dominated the situation as did the reptiles of this age. +They were not only abundant; they were frequently enormously large. +Their skeletons are among the most interesting that we find to-day. +Gigantic lizards, seventy feet long and eighteen feet high at the +shoulders, dragged their heavy bodies through the marshy edges of the +lakes. Out upon the land others, not quite so heavy nor so large, +roamed about, some of them feeding upon the soft vegetation, others +having teeth fitted to tear down their herbivorous cousins. In some of +them the hind legs and tail were very heavy and the front legs so +light that it is quite clear they must have hopped around as do the +kangaroos to-day. Others of these reptiles went back to the sea, lost +the leglike development of their limbs and regained the flipper form, +though the bones of the fingers and toes are singularly +distinguishable in the paddle. + +Strangest of all, a considerable group of these wonderful reptiles +lengthened their little fingers, sometimes to three or four feet in +length, and had a skin stretched from these fingers over to the body +in such a fashion as to give them wings not unlike those of the bat. +In the wing of the bat, however, four of the fingers of the hand run +through the membrane and support it. In the pterodactyl, as these +flying reptiles are called, the middle finger supports the web, while +the remaining fingers can still be used to clasp objects or serve the +animal to lift himself, as the bat can do with his thumbs. + +Meanwhile an entire change is coming over the plant world. The last +third of this age of reptiles is known as the Cretaceous or chalk +period. Now, for the first time, the forests begin to take on more of +the character of our forests of to-day. Plants like our willow and +beech, poplar and sassafras appear in great abundance. Their broad +leaves serve better than those of any earlier plants to catch the +sunlight. But in addition they offered such effective evaporating +surface that they cast off rapidly the moisture obtained from the +ground by the plant. Accordingly in the winter season, when the water +in the ground is frozen and not available for plant purposes, they +were forced to throw away their leaves. It is quite possible that up +to and including the time of the Carboniferous, plants were all +evergreen. There had been before this little variation in climate over +the globe. Life in the Cretaceous begins to take on distinctly its +modern form. + +Among the reptiles of the forest there appear to have been a few small +creatures which to an observer of those times, if there could have +been an observer, would have seemed of the utmost insignificance +compared with their giant cousins. + +These little creatures climbed up into the trees to escape their +enemies. There were some in whom the skin, in front of the elbow and +behind the wrist, was loose, and stretched across the joint a little +like the wing of a bat. This reptile, climbing into the trees to +escape its enemies, found that this loose flap of skin served it +nicely, and sailed out of the trees in a manner not unlike that of +the flying squirrel of to-day. Among these experimenters in aviation, +certain forms produced scales which became elongated and finally slit +up along the side. These slit scales slowly developed into the +feathers of the birds of to-day. Whether the steps by which the change +occurred have been correctly stated or not, the result is sure. In the +rocks of the chalk period we find the remains of an interesting +creature. If nothing but its bones had been found it would have been +called a reptile. It had a long tail, it had claws on its front limbs; +it had teeth in its mouth; it had a flexible backbone. All of these +are reptilian rather than bird characters. Yet on the rocks +surrounding these bones are the unmistakable impressions of the +feathers of the wings and of the tail. Nothing in the world to-day has +feathers excepting the birds, and in this "ancient winged thing," for +this is the significance of its name--archaeopteryx--we have perhaps +the most remarkable link in the world between two distinct sections of +the animal kingdom. Here is a creature half reptile, half bird; +perhaps one-third reptile and two-thirds bird. It was about the size +of the crow. A little later unmistakable bird skeletons will appear, +but still their jaws are provided with long conical teeth. + +Still more interesting from our standpoint is another set of primitive +animals, utterly insignificant in appearance, but of momentous +importance on account of their later history. Among these reptiles +were a few small creatures perhaps not much bigger than mice or moles. +Their teeth were a little more complicated and specialized than the +teeth of their reptilian cousins. Between their scales were small and +sparse hairs. Almost nothing but their jaws remain to-day to tell us +anything about them. But in this humble little creature of the +Mesozoic, utterly insignificant beside the tremendous reptiles of the +time, we discern the ancestor of the mammals. These were the +progenitors of the horses and cows, of the cats and dogs, of the +monkeys and apes, of the men of to-day. + +During this chalk period, which forms the last portion of the age of +reptiles, life for the first time grew to look much as it does to-day. +Now, apparently, the cold of winter and the heat of summer followed +each other in regular succession. There have been colder and warmer +periods at various times in the previous history of the earth, but +undoubtedly they were more uniformly cold or uniformly warm than now. +Ages were warm, or ages were cold, but now the earth clearly shows the +annual alternations of summer and winter, and for the first time +clearly shows the bands of climate on the earth which we know as +zones. + +In the chalk period this new factor of cold works mightily in favor +of the mammals. Their reptilian ancestors were cold blooded. When the +climate was warm they were active; when the climate was cold they were +sluggish. With the continuation of the annual alternations of cold and +warm weather that had now set in upon the earth, the little birds and +mammals had in their warm blood an advantage which, in the long run, +enables them not simply to compete with their reptile forefathers, but +to outdistance them absolutely in the race. Here and there, on earth +to-day, exist a few big reptiles like the crocodiles and the boa +constrictors. But they are few and comparatively insignificant among +the multitudinous population of the globe and are confined to the +hotter portions of the earth. For the most part, the reptiles now play +an insignificant and unobtrusive part. The little molelike creatures, +practically unnoticed between their feet in the later Mesozoic, have +come to supplant them entirely, and almost to rival them in size. +While the reptiles have grown steadily smaller, the mammals have +steadily become larger. + +While there is no land mammal to-day as big as the heaviest of the +reptiles in the Mesozoic, the whale, which is one of the mammals that +has again taken to the ocean, surpasses in size even those gigantic +creatures. There never lived in the world before a creature quite so +big as the biggest of our whales. Size, however, is not the most +important point in any animal. Speed, sagacity, variability, and power +of adaptation, these are the qualities which the world prizes, and +these the new mammals possessed. + +The next geological era is the Cenozoic, or period of modern life. +This is divided into two quite distinct sections, the Tertiary and the +Quaternary. This era began about five million years ago, roughly +speaking, and is still going on. The greater half of it is known as +the Tertiary. It was during this time that the mammals came to their +own. At first these creatures belonged to what the scientist knows as +generalized types. They are jacks-of-all-trades. The student of early +animal life finds in the little Phenacodus, which was scarcely bigger +than a good-sized setter dog, the beginnings from which many forms +have subsequently developed. This creature showed points of structure +which to-day may be seen in such diversified animals as the dog, the +horse, the rabbit, and the monkey. It is not, of course, suggested +that Phenacodus was the immediate ancestor of any of these. But there +were no animals in those times more like these I have mentioned than +was Phenacodus, and from forms like it in main features all of these +other animals have since been derived, each species of animal having +become adapted to one particular kind of life. The development of +diversified situations on the earth, the varieties of climate, the +variation between marsh and upland, between valley and plateau, +furnish a complexity of environment into each niche of which a new +form of animal fitted itself. + +With the increased complexity of mammals comes the submergence of the +reptiles and amphibians to-day. In all sorts of situations we find +mammals. The old-fashioned continent of Australia is separated from +everything about it by deep water, impassable to any animal which +lives upon it. In this secluded country evolution is very slow and +animals are very antiquated. We still find there mammals with the +ancient habit of laying eggs in a hollow in the ground, though after +these eggs are hatched the young are nursed on the milk of the mother. +But on the great continental stretches, where competition is keen, +where the animal must battle for his life against a wide field of +other animals, where migration into new situations is possible, the +rapidity of the development has been very much greater. + +It is in such a situation that man has arisen. In the extreme +southeastern portion of Asia, and on the islands lying close to the +coast, his highest non-human relatives, members of the ape family, +have reached their best development. These, of course, are not man's +ancestors. They are the less progressive members who are left behind +entirely in the race. Whether we have to-day any traces of the steps +by which man arose from the animal beneath him is vigorously disputed. +Eminent scientists will be found on both sides of this question. + +Many scientific writers to-day take it for granted that one form, +discovered in Java, while it may not be in the absolutely direct line, +must be very close indeed to the line of ascent toward man out of the +apelike forms. A scientist by the name of DuBois, working in the banks +of a stream in south-central Java, found a thigh bone which seemed to +him exceedingly human in its general character and yet not absolutely +like the human thigh bone. The oncoming of the rainy season raised the +water in the river so that DuBois could not continue his search. +Returning a year later, and digging back deeper into this bank, he +found a skull cap and two molar teeth which seemed to him to belong to +the thigh bone, although they lay several yards farther back, but at +the same level in the bank. + +When these bones were subsequently presented to a meeting of European +scientists by DuBois, he claimed to have found the "missing link" for +which there was so eager a demand. Some of the best anatomists of the +meeting, notably Virchow, laughed at his claim and said that the skull +cap was simply that of a human idiot, and could be duplicated in any +large asylum. A committee of twelve naturalists was appointed to +report upon DuBois' find. Of this committee three asserted the bones +to be those of a low-grade man, three insisted that they belonged to a +high ape, of a type somewhat higher than any we know to-day, but still +distinctly an ape. Six members of the committee of twelve agreed that +the remains were those of a creature higher than an ape and lower than +any normal man, and represented, in their opinion, a stage distinctly +along the line of development out of the apes and into man. + +This so-called "Java find" is known in science by the name of +Pithecanthropus, which means the ape-man. Whether we look upon this +fossil as a serious find or not, it is very certain that in the caves +of Europe belonging to the Quaternary period we find abundant +evidences of primitive man. The older these evidences are, the more +likely they are to be distinctly below the grade of man of to-day, in +the size and shape of the brain case and in the length and massiveness +of the jaw. + +There are probably more races than one represented among these skulls. +Some of them are surely well-deserving of the title of low brow. Their +heavy ridges over the eyes, their small foreheads, their massive, +heavy-set jaws show a race of men far less endowed mentally and much +better endowed in the matter of brute force than the men of to-day. +These skeletons, or parts of skeletons, are turning up every year, and +we are just beginning to know much about them. Capable men are +studying them with much care. The next fifty years may not improbably +make the history of the ascent of man as clear as is now that of the +horse, to which we shall refer later. + +The whole question of the descent of man from the lower animals, or +his ascent from them, as Drummond aptly termed it, is to most people +so entirely repugnant as to set them at once, and finally, against all +willingness to consider the question of Evolution. This, however, does +not solve the problem. Even though truth be horribly unpalatable, it +is still to be believed if it is only the truth. There is practically +no doubt left among scientific men of the origin of man in lower +forms. The evidences grow more and more complete year by year, and +from every line of investigation. Whether we study his anatomy, his +embryology, his history, his language, or his civilization, all +indications point in the same direction. Constant discoveries indicate +the fact of an enormously long development from a very humble form. If +this proves to be true and remains unpalatable, the fault lies in the +palate and not in the truth. Gradually we are coming to understand +that there is no reason why this truth should be unpalatable. We +consider a rise from humble conditions to be the glory of our heroes; +we esteem it an added charm in their strength that they should have +developed from untoward surroundings. It is not a disgrace to man to +have descended from the apes. It is to the glory of man that he should +have ascended from forms not much more promising-looking than the apes +of to-day. We must repeat, however, that the apes were the +unprogressive members, and hence we must not judge man's ancestors too +harshly. It must have been in them to rise. But the great glory in the +thought of the humble ancestry lies in the possibilities of his +future. If out of a creature not materially unlike the gibbering ape +of to-day there should have come, under the guiding hand of an +Almighty God, creatures with the endowments and capabilities of man of +to-day, then this is only an earnest and foretaste of that which may +be expected in the future. A time will come when man shall have risen +to heights as far above anything he now is as to-day he stands above +the ape. Even then there seems no end. With Infinite Power as the +agent, and limitless time in which to work, man would be limiting God +to an extent unwarranted by the history of the past to imagine that +His process had stopped to-day, and that man, with his many +imperfections of body, of mind, and of morals, should be the best that +is yet to come. There cling to him still the limitations and dregs of +his brute life. Often the brute in him comes to the surface. Little by +little he is coming to be dominated by the qualities God has last +given him. Slowly the brute shall sink away, slowly the divine in him +shall advance, until such heights are attained as we to-day can +scarcely imagine. As we can scarcely conceive the beginnings of this +process, so we can with difficulty imagine its end. This only can be +seen by the Eternal through whom it shall all come to pass, and by +whom all will in time be accomplished. + + + + +CHAPTER VII + +HOW THE MAMMALS DEVELOPED + + +When the idea of evolution first began to be much discussed, +especially after the publication of the "Origin of Species," there +were several points which appeared to be more than commonly difficult +of explanation. It did not seem impossible that the various types of +domesticated cattle should have descended from a common ancestor. It +did not seem difficult of comprehension that the dog might once have +been a wolf. Though not quite so credible, it did not seem absurd that +the tigers, lions, and leopards should have once all been alike. The +resemblance between these are strong enough to make the idea seem +conceivable. Though men were willing to concede this much, they +insisted that the great branches of the animal kingdom varied so +widely from each other as to make it certain that each was a separate +creation. It was particularly objected that the mammals differed so +entirely from other animals in several important particulars that a +special divine act was necessary for their appearance. The mammals +have a furry covering entirely different from the clothing of any +other animal in the kingdom, and have warm blood, which is found +nowhere else except among the birds. But particularly their method of +producing their young seemed so entirely different from that of any +other group that here a special creation was deemed absolutely +necessary. + +Other young creatures are produced from eggs laid by the parent and +subsequently hatched. The young of the mammals are born alive and +comparatively well developed. In addition, their first food, the milk +of the mother, is so entirely different from the food of any other +creature that this again seemed to involve a separate creation. +Gradually we have come to understand the whole matter of reproduction +very much better. Minute and careful dissections of rabbits, of dogs +and cats, of animals slaughtered for food, with occasional post-mortem +examinations of human beings in various stages of the development of +the young, leave us no longer in doubt concerning the main features of +the process. The better we come to understand it the more clearly it +becomes evident that in the development of the mammals we have no new +procedure, but, as in so many other activities, new developments of an +old process. + +There are two entirely different methods by which new animals and +plants may arise. One sees sometimes in the home of a friend a +geranium of particular beauty, the like of which he would be glad to +possess. The accommodating friend cuts a small piece from the +geranium. This is stuck into poor but well-watered ground, develops +roots, and eventually grows into a geranium stalk exactly like the one +from which it came and of which it is in reality only a detached part. + +In similar fashion, if one wants a particular kind of apple, he never +trusts to planting an apple seed. Going to the tree of the variety he +desires, he takes from it a small twig provided with a bud and inserts +this bud into a cleft made in the young branch of another apple tree. +The young bud so inserted starts up into a new branch, resembling +almost absolutely, not the tree which feeds it with sap, but the tree +from which the bud was originally taken. + +When we wish a particular variety of potato we obtain pieces of the +potato of the kind we desire. Each of these must contain an eye, which +is a bud of the old potato. When the sprout appears the new plant will +be practically identical in character with the plant from which the +potato was taken. This sort of reproduction, in which a piece of the +old parent grows up into the new generation, is called the asexual +method. But one parent is concerned in the process, and the offspring +are as nearly as may be like the parent from which they arose. + +The gardener who wishes to obtain new varieties is not content with +this method. If he plant the seed of the potato the outcome will be +most uncertain. His seed must be taken, of course, from the fruit of +the potato, and most of these plants never fruit. Every grower of +large quantities of potatoes will have noticed occasionally, on the +tops of the plant, after the flowers disappear, a globular growth +looking not unlike a small tomato, but with a tendency to become +purplish green in color. This is the fruit of the potato and in it are +the seeds. When these are planted all sorts of potatoes are liable to +start up. Most of them will prove worthless. An occasional seed may +produce an uncommonly fine plant. This new variety may thereafter be +propagated from the tuber, as the potato itself is called, and the new +strain will be kept constant in this way. This method of using the +seed for reproducing the plant is called the sexual method, because +two parents cooeperate in the production of the seed. The pollen came +from one parent and the ovule, which after fertilization swelled up +into the seed, came from another. By this combination of two +individuals new varieties become quite possible. Nature seems to be +more concerned in improving her strain than in maintaining her older +strains. In all of her lowest plants and animals she uses the asexual +method of reproduction. As we go higher in the organic world the +two-parent method becomes increasingly common. When we reach the +higher animals, and most of the higher plants, this plan of double +parenthood, the sexual method, alone is used. + +In order that we may the more clearly understand how the mammals +produce their young and nourish them, we shall begin at the lowest +class of the backboned animals and note how the process is there +accomplished. As we pass upward through the kingdom the method +acquires greater complexity. When we finally reach the mammals, what +at first seemed an absolutely new process will prove to be, as is all +of nature's work with which we are thoroughly acquainted, but a +modification and an elaboration of some previously existing process. + +Some time ago I was passing the early months of summer by the side of +a lake in northern Pennsylvania. Near my tent, on the edge of the +water, was a wharf from which it was possible to look down into the +shallows about the edge of the lake. In early July the bottom began to +take on a strange appearance. Spots as big as a dinner plate became +evident because they were cleaned of the finer sand or mud which is +common on the bottom. A close examination showed that each of these +circular spots was being occupied and cleaned up by a sunfish. The +pebbles were lifted into the mouth of the fish and driven out again +with force. The water which emerged with the stones seemed to wash +away the dirt, while the pebbles themselves became gradually cleaned +of the green plant life which ordinarily covers them. After the +process was completed each spot was saucer-shaped and free from scum +and mud. Over each of these spots hovered the sunfish which made it, +and round and round the fish swam. The circles thus traversed were so +near each other that every now and then the occupants of two adjoining +nests would meet on the border. The fish which was most nearly on its +own ground would at once attack the other and drive him away. In a few +days the other partner in each family seemed to appear. Now two fishes +swam side by side over each nest, bringing the lower edge of their +bodies comparatively close together. In this position they moved +around over the pebbly bottom. The female was discharging her +multitudinous and very small eggs, so that they dropped to the bottom +of the nest. At the same time the male was expelling what in fish is +known as the milt. In this milt are the sperm cells of the male, each +consisting of a rounded head and a very slender body. These are +attracted by the eggs. Pushing up against them, the head of a sperm +cell, consisting almost entirely of the nucleus of the cell and +carrying the determinants which were to decide one-half of its future +characters, penetrated this egg and fused with its nucleus. This was +filled with the determinants of the characters inherited from the +mother. Of course many of the eggs, of which probably there are a +thousand, must have escaped fertilization. There are doubtless a +thousand sperm cells that went to utter waste for one which found an +egg to fertilize. These eggs nestled in the crevices between the +stones in the warm water of the edge of the lake. Here the sun could +easily penetrate to the bottom and hatch them. The little fish, still +guarded by one hovering parent, swam around in the water long before +the yolk of the egg, containing its large amount of food, had been +absorbed into the tissues of the young fish. This fatty store made the +abdomen of the fish in which it lay protrude enormously. Gradually the +fish grew larger and the yolk grew smaller until all had been +consumed. Soon the fish began to forage for himself and no longer to +demand or care for the company and protection of its parent. The +little sunfish is highly favored among his comrades in having any care +whatever by the parent. In the case of most fishes the female, +swimming slowly over the bottom, deposits her eggs, which are +fertilized by the male, which follows behind her. After the eggs have +thus been laid and quickened no other attention is paid to them by +either of the parents. + +Fish are stupid almost beyond the comprehension of those who are not +students of the minds of animals. Frogs and toads are a distinct step +in advance, and hence their mental activities play a larger part in +the process. + +In the love-making of the frogs and toads the song has an important +share. In each species the voice is a little different from that of +any other. In our familiar garden toad we have an excellent +illustration of the method common to the entire group. When spring +comes an impulse seems to stir in all the toads of a neighborhood. +Heretofore they have stuck faithfully to dry ground; now they start +off for the water. Whether their impulse is simply to move down hill +or whether they by some means detect the near presence of water, I +cannot say. Certainly a new fountain on a lawn will secure in spring +its prompt and full share of the neighborhood's toads. In any event +the toads of a district congregate in great numbers in any pond or +along the edge of any moderate stream. Within a short time their +flutelike, quivering voice is heard far and wide. That this note has +an attractive power over the female there is no doubt. She herself +makes no effort to imitate, but the song of her mate is persistent and +exceedingly sweet. I have seen a male sit upon a clump of grass and +utter his love call. Before he had been singing for more than half a +minute three females hastened toward him from a distance of perhaps +twenty feet. Each seemed anxious to reach as promptly as possible the +creature whose voice had proved so attractive. When the mating comes, +the female discharges a series of small shotlike eggs which are +encased in a very tenacious mucous. While they are being deposited the +male fertilizes them. No sooner have the eggs, fertilized by the sperm +cells, reached the water than the mucous at once begins to swell. The +result is that eggs appear encased in two slender strings of jelly, +each having a diameter about that of a lead pencil. At intervals of +not more than half an inch the shotlike eggs may be seen. The mother +toad, in laying these eggs, moves about rather restlessly in the +water. By this means she succeeds in wrapping the strings about the +grass and sticks of the pool. This will hold them quite safely even +against a considerable current of water, should the stream rise and +flood the side pools in which the eggs are laid. With this amount of +care, however, the attention of both parents to the young entirely +ceases. They are now abandoned to the chances of a fortune to them +exceedingly unkind. A toad will lay about five hundred eggs. It is +evident that on the average only two of these can attain maturity by +the time the parents have died, for the number of toads does not +materially alter season by season. The connecting string is made up +not of nourishment for the eggs, but of a bitter mucous so unpleasant +to the taste that fish are thus deterred from eating the otherwise +nourishing material. This secures for the young embryo a chance to +mature which in the absence of the jelly it would entirely lack. +Imbedded in this mucous is the embryo itself, surrounded by a small +amount of albumen and containing inside of itself a very considerable +amount of yolk. This gives to the egg a volume possibly a hundred +times that of the egg of the sunfish. Thus, even counting the care the +parent sunfish took of its offspring, which care is very uncommon +among fishes, the toad stands a distinctly better chance in life. The +protection of the bitter mucous and the large amount of yolk +permitting considerably larger development before leaving the egg, +give to the toad a material advantage. When the toad first emerges +from the egg it is amazingly like the fish. It has gills at the side +of its neck and swims by the movement of its tail. Later its limbs +develop, the hind ones coming first, its tail is absorbed, and it is +now a true toad, ready to leave the water. + +Altogether a higher state of reproduction is encountered when we reach +the reptiles, which are the next higher class of backboned animals. +Here very distinct developments of the process are discovered. The +turtle, to use the best known illustration, may lay but twenty eggs. +But she will not lay them at random in the water, as do the toads and +the fish. Each egg is wonderfully fattened with yolk. This means that +it is possible for the creature to develop to a far greater extent +before leaving the egg than was possible in the case of the toad. +Accordingly the little turtle, while it begins life not unlike a fish +and goes through the gilled and tailed period, during which it is not +unlike a tadpole, passes beyond this period before leaving the shell +and has already acquired its full turtle characters when first it +steps upon the scene. So big an egg as this would be highly nutritious +and animals would desire it immensely for food. Hence it becomes +necessary for the turtle to securely hide her eggs. In order to do +this, she scoops out a pit in the sand in which she deposits them and +here they develop. If no further provisions were made the eggs of the +turtle would dry completely and never hatch. Accordingly it becomes +necessary for the turtle to enclose each egg in a tough, leathery +membrane, known as the shell. Because the egg is thus encased it is +necessary for it to be fertilized before being laid. Accordingly the +male must place the sperm cells within the body of the female. These +cells swim nearly to the top of the tubes in which they are placed, +and there fertilize the descending eggs. Farther down the canal the +shell is secreted about the now swollen mass of yolk and white, +completing the egg just before it leaves the parent. + +If the evolutionist understands properly the line of descent, the +birds and mammals are both the descendants of the reptiles. While +there is less exterior resemblance between a chicken and a turtle than +between a cat and a turtle, the real relationship in the first case is +much closer than in the second. This is perhaps most easily seen in +the scaly legs of both bird and reptile. Another remarkable +resemblance lies in the fact that in both cases the eggs are large, +well stored with nourishment, and protected by a resistant shell. + +So few people know the turtle's egg that it will be better to describe +that of the hen, which it largely resembles. Underneath the hard shell +is a tough but flexible membrane which lies against the limey coating, +except at the blunt end, where a separation between the two gives room +for a bubble of air. Inside of this shell and its membrane lies the +white of the egg, which is nourishment for the chick, though not +nearly so rich as the yolk. This, besides the albumen which it +contains, is stored with large quantities of fat. It will be +remembered that upon breaking a hen's egg and dropping it into a bowl, +the yolk holds together because it is enclosed in a delicate sac. As +the yolk falls into the bowl there floats to the top of it a lighter +yellow spot as big as the end of a lead pencil. This is all of the egg +which thus far represents the chick itself. All the rest is +nourishment. This disk already consists of three reasonably +distinguishable layers of cells, which grow rapidly different from +each other. They spread and bend and twist, forming the young chick +and a set of organs which serve for its protection and maintenance +during its embryonic life. Within a few days these accessory organs +will have formed distinctly. Within the upper half of the yolk will be +found the small developing chick, which for the first thirty-six hours +of its development passes through a stage not unlike the fish, or the +earlier steps of the turtle. Within a few days it becomes clearly +evident that this creature is to be a bird, though it is much longer +before it is clearly a chick. + +This embryo is so soft that it is almost like curd in thickened milk, +and could be very easily destroyed were it not for a protective device +which Nature has employed. It seems necessary that it should be +protected with the utmost care. The matter will be better understood +if we recall a common experience. Almost everyone has tried to +dissolve some substance in water in a vial. If the bottle be filled +with fluid to the top and corked it is very difficult to shake up the +contents. Even vigorous agitation produces little movement of the +material on the inside. If we wish to shake up the solid with water +the bottle must be left partly empty. The brain of a human being is +protected by just the same device. If it simply lay within the skull +the first fall would mash the gray substance against the side of the +cavity. To prevent this calamity the bony case is made somewhat larger +in capacity than the brain itself, and the space between the two is +filled with a watery fluid. This serves to prevent jars and shocks. In +the hen's egg the same plan is pursued. The embryo lies on the inside +of a bag considerably larger than itself. This sac, called the amnion, +is filled with a watery fluid. With such a protection only the most +severe shock to the egg would sufficiently jar the embryo to do it any +harm. The ordinary experiences of an egg leave it undisturbed. + +Every living creature requires a constant supply of food and of +oxygen. The embryo is a living creature, and is no exception to the +rule. It needs an abundant supply of easily assimilated food and of +oxygen. When the hen's egg is first laid the entire contents, with the +exception of the little light-colored disk which floats on the top of +the yolk, form the nourishment. The disk alone is the living organism. +In the earliest stages the embryo receives its food by simple +absorption from the yolk. As the chick increases in complexity the +yolk at first grows swampy, with fluid trickling here and there +through the more solid portions. Thin walls form about these little +streams, thus producing blood vessels which cover the entire surface +of the yolk. These absorb the nourishment and turn it over to the +embryo. As the latter grows in size both the yolk and white diminish. +The embryo soon becomes larger than the remaining yolk and is attached +to it by a cord filled with blood vessels which enter the chick near +the center of its body. The abdominal wall has an opening at this +point. One of the later occurrences in the life of the chick, before +it breaks through the egg, is to have the last remnant of the yolk and +its sac slip to the inside of the abdomen, which then completely +closes over it. + +As yet, we have seen no arrangement for furnishing air to the chick. +At the same point at which the blood vessels from the yolk enter the +chick, another set of vessels pass in and out. These are attached to a +large flattened bag which floats above the embryo against the upper +side of the shell. This bag is called the allantois, and serves as a +sort of lung for the developing chick. The shell is porous enough to +allow air to pass through it. The blood vessels of the allantois take +in oxygen and give out carbon dioxide through the porous shell. The +blood thus altered is returned to the chick and serves its life +purposes. One of the reasons why the chicken must turn its eggs in the +nest is that, if the allantois remain too long in contact with the +upper shell of the egg, it will become attached to it and will not +thereafter perform its functions. + +The embryo thus enclosed in the egg finds its protection in the fact +that it is encased in a fluid contained in the amnion. It draws its +nourishment from the yolk upon which it lives and the nourishment is +transmitted to it by blood vessels. It draws its oxygen and throws off +its wastes through the instrumentality of the allantois, which covers +it over. Day by day the chick becomes larger, day by day it grows to +look more like what it is to be. By the nineteenth day it appears to +be complete. Its nervous organization is, however, not thoroughly +developed. If removed from the shell the chick still is indisposed to +stand upon its feet or to run about. If allowed to remain in the egg +until the twenty-first day, the chick will be able to push its beak +through the skin enclosing the bubble of air at the blunt end of the +egg and get the first breath into its lungs. Now it gives a faint +peep, breaks the shell of the egg, and steps out into the open air. + +I have given this somewhat lengthened description of the development +of the chick because of the light it throws upon the method pursued by +the mammals. The features which have been described in the case of the +chicken's egg could be as fully observed in the case of the turtle or +any of the other reptiles. Mammals are descended from the reptiles of +the Mesozoic, and whatever peculiarities there may be in their method +of producing their young must be derived from the reptiles. If we wish +to know how the earliest mammals produced their young, we can only +judge by the lowliest members of the group that live upon the earth +to-day. The most primitive of these is the so-called Duckmole, of +Australia. This little creature has habits not unlike those of the +muskrat. It burrows in the bank of a stream, and makes a nest at the +end of the burrow, where it lays its eggs. This is one of the very few +warm-blooded, hair-covered animals which still lays eggs. A little +higher in the scale stand the kangaroo and the opossum. These +creatures keep the egg inside of the body until it is hatched. But +this happens in so short a time that the young animal is exceedingly +immature and as yet unable to stand the outside air. Accordingly there +is a double fold of skin on the abdomen of the mother, covering her +breasts. This forms a suitable resting place into which these young +are conveyed as soon as they are born and from which they do not +emerge for many days. The little creature instantly fastens upon the +nipple of the mother, keeping its mouth constantly in this position. +At intervals the muscles of the breast force the milk into the mouth +of the young, which is still too undeveloped to suck for itself. As it +gets older the little opossum or kangaroo emerges from the pouch in +the pleasanter part of the day and in the absence of danger. It +returns to the mother's pocket as soon as it becomes cold or a cry +from its parent warns it of its defenseless position. + +These creatures are the lowliest of the class upon the earth. The +great majority of all mammals have elaborated a far finer plan, in +which the young are retained within the body of the parent until they +are quite able to stand the air. The length of this time varies in +different mammals from a few weeks to more than a year. The egg must +be fertilized before it leaves the body of the parent. If it should +fail in this it simply passes out and is wasted. If the fertilizing +cell reaches the egg before it has progressed far down the tube it +begins its development. The embryo forms for itself the sort of head +and tail and gill slits which would have served its fish or its +tadpole ancestor. Its limbs develop as little buds indistinguishable +from similar buds that would have formed fins for the fish or wings +for the bird. + +Around the embryo there forms a sac, the amnion filled with a fluid +which serves to protect the young mammals exactly as the growing chick +was protected. Under the forming creature there hangs a small but +empty yolksac. This is an actual remnant, a reminder of the past, when +the eggs of the mammals were also packed with yolk and the growing +embryo secured its nourishment exactly as does the maturing chick. But +a new method has been provided for the mammal, and consequently the +yolksac, though it has not entirely disappeared, has no nutritive +content for the growth of the embryo. + +The allantois of the chick now gains a new development and an altered +function. In the case of the chick it floats against the shell of the +egg and absorbs oxygen through the shell. Inside the body of the +mammal this is impossible, because the air is too far away. No shell +is formed about the egg because it is not to be laid. The tube of the +parent's body in which the egg lies becomes thickened at the point of +contact with the egg. It grows spongy and full of blood vessels. +Meanwhile the allantois is also growing spongy. These two tissues are +so closely pressed against each other that the blood vessels of the +transformed allantois mesh in with those of the thickened parent +wall. Thus the blood vessels of the mother are brought into close +contact with those of her offspring. Her blood seeps over into the +transformed allantois which is now called a placenta. From this it is +handed over to the offspring, which thus receives from the mother her +blood, and returns its own used blood for enrichment and purification. +So the allantois of the reptile has become the placenta of the mammal. +In the first instance it served only as an organ of respiration. Now +it has come to supply the embryo with rich blood containing both food +and oxygen derived from the mother. After the offspring is born this +thickened pad breaks loose, and subsequently is also extruded from the +body, forming what is known as the afterbirth. + +Thus far we have spoken of the change in the method by which the young +are brought to such a stage of development that they can stand the +outer air. One of the improved differences between the mammals and +other animals lies in the method by which they nourish their young for +some time after birth. The very word mammals signifies an animal who +is in the true sense of the word a mamma. This name for mother is +given to her because of the fact that she possesses what are +technically known as mammary glands, or, in simpler language, breasts. +It would seem as if here we had an entirely new organ. No other +animal gives nourishment to its young in such fashion; all mammals do. +What is the origin of the habit? How did the organ arise? + +A part of an animal's body that has the power to gather material from +the blood and pour it out in the shape of fluid is known as a gland. +Sometimes a whole organ does nothing else. Sometimes small glands are +scattered through, or over, the surface of another organ. There are +two kinds of glands in the skin of the mammal. The best known and most +frequently thought of are those which pour out the perspiration. These +have a double function. In the first place they assist in keeping the +temperature of the body uniform. When we are too warm they pour out a +watery fluid over the surface of the body. If the air is dry enough +and our body not too closely protected by clothing, this perspiration +passes off in the form of vapor. All evaporation requires heat, which +in this case is extracted from the body. So soon as the temperature +returns to its normal level the flow of perspiration ceases. The other +function of the sweat glands is to take from the blood some of the +waste matters of the body and pour them out upon the surface. This is +done in order that the body may free itself from substances which, if +they were to accumulate, would have a poisonous effect upon its +action. It is this function of the sweat glands which makes it +necessary for us to bathe the surface of our bodies with water. Dirt, +in the ordinary sense of the word, is not harmful to a sound skin. Our +reason for bathing is really to remove the wastes which we ourselves +have poured upon the surface of the skin. These, if allowed to remain, +soon decompose, like all nitrogenous substances, and become very +offensive. They may then be reabsorbed into the skin and nature's +effort to throw them off has been in vain. These glands, since they +contain waste matter, could not possibly yield food for the young. +They would poison and not nourish. Hence, whatever the breasts may be, +they are not altered sweat glands. + +There is another set of organs in the mammalian skin. At the base of +each hair lies an oil gland. The function of these is to pour out a +substance which spreads along each hair and over the surface of the +body. The outside of the skin is always dead, and would easily crack +were it not for the constant secretion of this oil. In winter, when +the blood circulates less freely and these glands consequently pour +out less oil, the supply frequently runs short. If what little is +poured out is too frequently removed by washing, the skin becomes +brittle, and, on bending a joint, the epidermis cracks. The gloss of +the hair is due to the oil thus poured out. This oil becomes one +ingredient in the milk produced by the transformed gland. But there +is another important constituent. When one does unaccustomed manual +work the ordinary result is the formation of a blister. The epidermis, +or scarfskin, becomes detached from the dermis, or true skin, and the +space between the two rapidly fills with the fluid portion of the +blood, known as lymph. The fact that no blood vessels have been broken +in this detachment results in there being no red corpuscles in this +fluid. Wherever a cavity forms in the body lymph is liable to enter +it. + +The milk glands of the mammals are modified oil glands. The fluid +which they now pour out is no longer exactly the old oil with the +addition of the lymph. Undoubtedly in the past the first milk was more +like this simple mixture. There seems no doubt that the breasts of +to-day are the enlarged and modified oil glands of earlier mammals. In +one of the most primitive of our mammals the young simply lick certain +bare spots on the surface of the mother's abdomen. As higher forms +arise there develops a smaller or larger mound with a distinct +projection, about which the lips of the offspring can easily fasten. +Lamarck would have said that the suction of the infant had produced +such a mound, and that this had been transmitted to later offspring +until it had grown to be the highly developed organ we now find, for +instance, in the cow. Since, however, we have come to disbelieve in +the transmission of acquired characters, this explanation will no +longer serve. We must content ourselves with saying that, by whatever +accident the nipple arose, the success of it when present determined +its selection by nature and its consequent persistence. With increase +in its function has come increase in the size of the glands. Lower +animals which, like the hog, produce a large number of offspring, +possess a large number also of these glands. With the diminishing +number of young and greater care of them as we rise in the scale has +come also a diminishing number of breasts in the female. Whether those +on the front of the body should persist, or those on the rear, depends +upon other factors in the life of the animal. Hoofed animals, perhaps +because their best weapon is the hoof and they can there best protect +their young, have retained them in the rear of the body. In the group +of animals known as the primates, including monkeys, apes, and man, +the habit of holding the young in the arms for protection has +determined the persistence of the breasts upon the chest rather than +the abdomen. + +It is interesting to notice that the habit of the elephant of +protecting its young by means of its tusks has also resulted in a +similar position of the milk glands. + +That the primates had once a larger number of offspring is confirmed +by double evidence. Even to-day the number of children at a birth is +often two, sometimes three, rarely four. The day before this was +written came the report of a case of five children at a birth, all of +whom seemed sound and all of whom lived. Still more direct evidence is +found in the fact that occasionally in the human female there are two +pairs of breasts, and very rarely three pairs. These are then disposed +in a double line down the front of the body. + +The new plan of caring for the young is one of the priceless heritages +of the higher animals. As we rise in the grade of life the number of +the young produced at one time steadily diminishes, while the care +spent upon them increases. The shad may lay four hundred thousand eggs +and trust them entirely to their fate. The sunfish will lay a +thousand, by no means all of which can be fertilized, but it guards +them somewhat after deposition. The toad lays several hundred, stores +them with a considerable amount of nourishment, and protects them by a +bitter deposit of mucous. The turtle has reduced the number of eggs to +perhaps a score. Each of these is supplied with abundant nourishment, +so that the young may develop to considerable size and activity before +emerging from the egg. This material is enclosed in a firm protective +shell and hidden away from sight by being buried in the ground. In the +mammals comparatively few eggs are produced at one time. These are +fertilized within the body of the parent, are attached to the parent, +and absorb her blood. No shell is needed because nothing will kill the +developing offspring that is not likely to injure the parent. Not only +do the young feed upon the blood of the mother up to the time of +birth, but they are practically dependent upon this same blood after +birth. Though they do not take it directly from the veins, the milk +is, none the less, the transformed blood of the mother. This assures +the young of food as well as of protection. Best of all, the young are +provided with the companionship of the mother. Now for the first time +animals learn by example. Heretofore they have been born with a nearly +undeviating instinct; now intelligence begins to arise. They can +imitate their mother. Heretofore no acquired characters affected the +young. In the mammals, although the young cannot inherit the acquired +habits of the parents, they can get them by imitation, which serves +nearly as well. + +There is, however, a more wonderful advantage that comes from the +close attachment between mother and offspring. This intimate +relationship brings about an affection of the mother for her young +heretofore unknown in the animal world. It is somewhat paralleled +among birds, but here the care of the nestling is less intimate, far +less maternal, than the care of the mammal for her young. As the +number of the young grows less and the care taken of them increases, +the intensity of the affection also increases. By the time we get as +high as the dog or the cat this fondness becomes a fierce, +self-sacrificing love. When we come to man, with his high intellectual +powers, with his deeper moral sense, we find a wonderful change. This +love of the mother for her child has grown into the finest emotion +possible to the human heart. It no longer is confined to the dependent +life of the child, but follows the offspring through its entire life, +guiding, guarding, shaping its destiny, handing on to the child the +treasured wisdom of the race. Influenced by the example of the mother, +the father comes to have a love for his children. It is not so strong +as that of the mother, nor so utterly unselfish, but it is still a +noble and exquisite love. Developing in a different direction, the +love of the mother for her children grows as civilization advances, +and spreads over the father of those children as well. Again +reflecting her love, the man finds himself filled with a new feeling +for the woman. It is never as unselfish, as free from desire, as is +her love, but it completely transforms his relation to her. What has +been with him simply desire is ennobled and enriched until it becomes +the finest passion of his life, absolutely transforming him, in +relation to her, from a selfish brute into a tender and life-long +companion. So utterly does the love thus engendered transfigure human +life that when we seek to express the divine nature in human terms, +and these are the only terms we know how to use, the richest +revelation that has come to us is the conception taught by the Master +that "God is Love" and that "as a father pitieth his children, so the +Lord loveth them that fear him." + + + + +CHAPTER VIII + +THE STORY OF THE HORSE + + +Ever since men have been familiar with the idea of evolution there has +been a temptation on the part of the zooelogist to draw up pedigrees +expressing the relationship between the various groups of the animal +kingdom. The impulse is natural, and, if the resulting tables are not +accepted with too much confidence, the result is not undesirable. The +truth of the matter is that all of these pedigrees are more or less +hypothetical. They simply show what connection seems most likely. In +all of them are spaces filled with doubtful names. Each addition to +our acquaintance with the past history of animals necessitates +revision of our tables. The student of fossils, trying to rebuild in +imagination the world of the past, finds himself often strangely +unable to link these animals together. The result is that the more we +know of fossils, the more distrustful we become of the easy +connections we have been making between groups. Accordingly we are +more than commonly pleased when we find the clear indication of a +genuine pedigree, actually illustrated by real examples, following +each other in time through the geological history. A few of these +lines are gradually becoming plain, and none of them is clearer than +the pedigree of our familiar and much loved horse. The example is a +particularly interesting one, not only because of our affection for +the animal, but because the horse originated in all likelihood in +North America on the land occupied to-day by our Western plains. As +though he loved the country of his ancestors, he returned after having +circled the globe, and once more went wild in the home of his +forefathers. The problem was first worked out in Europe and later +elaborated in this country. Now the history gets its finest expression +in the American Museum of Natural History in New York City. The +collection of fossil horses in that institution surpasses in +completeness and in excellence of mounting and of sympathetic +restoration any similar collection representing the ancestry of any +other animal in the world. + +In the table of Geological Times, given in chapter six, the era of +recent life known as the Cenozoic is seen to occupy something like +five million years. This figure, as was previously suggested, is very +uncertain, and may be three or may be six, but is safely represented +in millions. Through most of this time stretches what is known as the +Age of Mammals, the Tertiary Age. Its close, occupying only the last +few hundred thousand years, is known as the Age of Man, the +Quaternary. Through perhaps three or four millions of these years +stretches the known pedigree of the horse. + +When we go back to the early Tertiary we find a forest, with trees +that shed their leaves, interspersed with glades, in which already the +grasses were beginning to be developed. This state of affairs had +existed but for a comparatively short time, geologically speaking. It +had come only in the latter part of the preceding era. Lake and swamp, +meadow and forest intermingled to make a rich and varied scene. Slowly +the land toward the western side of North America lifted itself into +plateau and mountain range. Slowly the westerly winds began to be cut +off by the barriers thus raised across their path. As they swept over +the plateau and down into the eastern plain their moisture came to be +diminished. Gradually a very different state of affairs set in. The +ground became harder, the forest became sparser, the plants became +higher and firmer, the grasses tougher and more wiry, and, by the time +the Quaternary arrived, a condition probably even drier than that of +to-day existed over our western highlands. Throughout this long +change, spread over millions of years, a creature which has become our +horse steadily persisted and steadily advanced. Side lines developed +which finally disappeared, but the main line kept on, and when the +Quaternary came the horse arrived with it. Many of the skeletons in +this series were known before it was realized what they were. As time +went on and intermediate forms were found, it became possible to +recognize these as ancestors of the horse and to assign them their +proper position in the family tree. + +[Illustration: THE EVOLUTION OF THE HORSE'S FOOT + +_After H. F. Osborne and Charles R. Knight. By permission of the +American Museum of Natural History._] + +The earliest of the forerunners of the horse with which we are +acquainted would certainly not be recognized as such by any but the +most careful student of animals, if we could see him to-day. He stood +not higher than a fox-terrier dog, though his shape was very +different. But he would probably be more likely to be classed with the +dog than with the horse by the hasty observer, for he walked with four +toes of each foot upon the ground as the dog does to-day. Like the +dog, he had hanging at the inner side of his front foot a little +useless toe. He was long in body, comparatively short of leg, a little +long of head and neck, and distinctly long of tail. His grinding teeth +had points on them not unlike a pig's, and possessed no apparent +resemblance to the wonderful curved and ridged surfaces seen on the +teeth of the modern horse. What his skin and hair were like can only +be conjectured. In the restoration which Mr. Knight has made, at the +suggestion of Professor Osborne, an interesting inference has been +drawn. That he was a creature of the forest is suggested by his +spreading toes, which would keep him from sinking in the soft soil. It +is consequently surmised that he was dappled with spots which allowed +him to rest unnoticed on the sun-flecked floor of the forest. Mane he +had none, and his tail was probably tufted slightly at the end with +hairs, which were increasingly short as they approached the top. He +had no forelock, and the hair along the ridge of his neck was a little +longer than the rest, and stood erect. Browsing about on the soft and +tender herbage of his woodland home, his teeth had as yet no tendency +to become specialized. The molars had mounds upon them, developing, +perhaps, more into the shape of the points of the hog's, but even +still quite generalized teeth. His main enemies, from whom, perhaps, +he could with little difficulty escape, were creatures related to the +hyenas of to-day. Perhaps, like their modern representatives, they +preferred eating their flesh tainted to exerting themselves enough to +capture and kill their prey. By the time we advance a little further +into the Tertiary, though still in its early portion, a remarkable +change has already come about. The fifth toe, which in the earliest +horse hung upon the side of the front foot, has completely +disappeared. The change in the hind foot has gone still further. The +hind leg in many animals evolves more rapidly than the front. The +heavy work of running is always done by the hind feet, while the front +feet serve rather as a prop to keep the animal from falling than as +the actual means of locomotion. Hence the hind feet and the muscles of +the hind quarters are almost always heavier than the front. Possibly +on the front foot the little fifth toe was less of an obstruction, and +persisted after the early horse had lost the corresponding toe on his +hind foot. This process has gone on still further in this second +stage, and the hind foot has but three toes, while the front still +has four. This is not the only advance. Already the middle toe of the +original set of five is becoming emphasized. The weight is thrown more +forcibly upon it, as with the human foot it is upon the inner or big +toe. The middle toe is growing larger and larger, and the nail upon it +is spreading around it and is growing firmer. The creature, too, is +standing more nearly upon his toes; his legs are getting longer; he +stands higher from the ground, and now has come to be the size of a +hound. + +We can only surmise why this creature should have undergone such a +change, but the presence of flesh-eating animals having the size of a +fox, and presumably of the fox's swiftness, probably tells the story. +The little bands of early horses, pursued by their carnivorous foes, +were slowly modified into swifter creatures. It is not so much that +running made them fast, as that the slow ones were continually being +caught. If this process of constant elimination of the slow members of +any herd is kept up long enough, the group will necessarily develop +speed. As time goes on, of these early horses those which happened to +have longer legs and stood higher upon their toes won in the race, and +handed on their qualities to their long-legged descendants. As the +animal rose upon his toes, the inner toe, corresponding to our thumb, +was first raised off the ground and rendered useless, while a similar +change came over the corresponding toe on the hind foot. The hard work +of running being done on the latter, this superfluous toe was more +detrimental there than on the front foot, and disappeared, +consequently, more rapidly. In time, however, it also disappeared from +the front foot. Gradually the further elevation of the foot lifted the +toe, which corresponds to our little finger, off the ground, and this +now disappears also. + +With increasing toughness of the grasses, as the climate becomes drier +and the region more elevated, the teeth of the horse are given harder +work. The points begin to spread into ridges and to unite with each +other in such way as to form the crescents, which are later to be so +characteristic of the teeth of the modern horse. + +By the middle of the Tertiary this ancestral horse has risen in height +until he is taller and heavier than a setter dog. Three toes are found +on each front foot. The middle toe is getting constantly more +developed, though the smaller toes are evidently still of use. The +ridges of the teeth are quite crescentic now on the outer side, and +becoming better adapted to the evidently firmer food which the +creature is obliged to eat. + +As we come toward the end of the Tertiary, the development which had +been all pointing in one direction has advanced very much further. The +creature now would be undoubtedly recognized by anyone as a horse. The +legs are longer and straighter; the middle toe has become the only +useful toe, though on each foot a smaller toe, slender and probably +useless, still hangs on either side. Two similar useless toes to-day +hang at the back of the foot of the cow, which is now walking upon her +two toes, which give her the appearance of carrying a cloven hoof. +That is to say, the first toe on the foot of the cow has disappeared, +the second and fifth hang useless and much diminished at the back of +the foot, while the third and fourth are both well developed and +serviceable in walking. + +The late Tertiary horse has grown to be the size of a burro of to-day, +though probably it was a little more slender. The teeth are quite +horselike, both in shape of the crescentic ridges on their surface, in +the length of the teeth in the jaw bone, and in the fact that the +crinkled edges of enamel on the upper surface are protected on either +side by dentine or by cement. These surfaces, being softer than the +enamel, wore away somewhat more rapidly and allowed the sharp edges of +enamel to stand up in ridges. This plan increases the grinding power +of the teeth. + +With the oncoming of the Era of Man the horse reaches his modern +splendid development. During the early Quaternary the horse was +perhaps in some of his representatives a larger creature than he is +to-day. Each foot now has but a single toe. The nail has spread around +firmly and heavily, until it has become a splendidly developed hoof, +permitting the animal to travel with speed over firm and often stony +ground. The side toes have disappeared completely from the outside of +the horse's leg, although upon removing the skin it is easy to find +the long splints, which are the remnants of toes, which have not yet +quite disappeared. His heel has been lifted in the air until it is +eighteen inches off the ground, and he is standing like an expert +dancer upon the tip of his toe. The body of the horse thus being +lifted far off the ground, a new development becomes necessary. All +through the growth of the creature the neck and head have been obliged +to lengthen correspondingly. Every animal must be able to bring its +head down to the level of its feet in order that it may drink. Various +animals use different methods to accomplish this result. The giraffe, +with his enormously long legs, has a correspondingly long neck, which +lowers his mouth to the ground. Even with this extended neck the +giraffe's legs are so exceedingly long that he is obliged to spread +his front feet when he wishes to reach the ground with his head. The +elephant has pursued exactly the reverse plan. Using his tremendous +head as a battering ram in fighting, and using his enormous tusks both +in battle and in uprooting young trees, a lengthened neck is +absolutely out of the question. Furthermore his front teeth have grown +so prodigiously that they would interfere with his getting his mouth +to water. Accordingly, his nose has lengthened its tip until it +reaches the level of his feet, and this nose becomes to him the main +organ of grasp and of touch. To drink, its end is inserted in the pool +and water is drawn up the nostril. If the animal were to attempt to +draw it all the way back into his throat, it would inevitably strangle +him by getting into his windpipe. Accordingly, when the nose is well +filled with water, the tip of it is inserted in his mouth, and the +water discharged by a quick puff. The horse has taken a method +intermediate between these. It had moderately lengthened both neck and +head in order to get to the ground with its nipping teeth, and thus to +gather the grasses which serve as its principal food. + +The mammalian teeth, while of four kinds, really in most animals serve +but two purposes. The front teeth consist of the incisors and canines, +and are used for biting. The hind teeth, consisting of premolars and +molars, are used for grinding. In the horse, the jaw has lengthened +between these two sets, carrying the biting teeth far forward of the +molars. It is this gap in the row of the horse's teeth which makes it +possible for us to insert the bit into his mouth. + +Now comes a strange accident into the life of our American horse. +Creatures of the same kin had been evolving in Europe and Africa, but +the developments are more distinctly horselike, it would seem, in our +own country. Then for some reason the horse disappeared completely +from American soil. Doubtless two things happened. First of all, some +of them migrated across a stretch of open country which then connected +America with Asia in the neighborhood of Bering Strait. These +creatures spread first over Asia and then over Africa and Europe, +leaving their skeletons scattered over this enormous stretch of +country. Asses and zebras are still found abundantly and widely +scattered, but the wild horse of to-day is seen only in western Asia. +What happened to those who remained in America we shall possibly never +know. Some surmise that a fly not unlike the tsetse-fly of Africa +killed them out. Perhaps the members of the cat family, which are +steadily growing larger and fiercer, fed on their young if not upon +the older ones, and exterminated them. Perhaps the Glacial period +which followed was too cold for them. But, whatever may have been the +cause these horses died out not only in North but also in South +America, to which country they had spread. + +The old world horse was the companion of man. The skeletons of those +found with early man in the caves of Europe look as if the horse had +been a creature to draw man's burdens and to serve him for food, +rather than to bear him upon its back. Its roasted bones are often +found about the old tribal fires. Upon the discovery of the new world +the Spaniards brought with them to Mexico and to the Mississippi +Valley the horses which carried them in their battles against the +Indians. In the course of these frays many riders were killed and +their horses roamed wild. Slowly they made their way to the western +plains; gradually they became tougher and more wiry; their diminished +hoofs learned to catch more carefully in the rocks of their mountain +home; and the mustang and bronco of more recent years are the +descendants of the little dawn horse, whose dainty skeleton is found +in the rocks over which his later descendants, after a long stretch of +perhaps four million years, are now running. + + + + +CHAPTER IX + +EVOLUTIONARY THEORIES SINCE DARWIN + + +In considering the value of Charles Darwin's work and its permanent +effect upon the thought of mankind, we must be careful to distinguish +between two phases of his effort. It was his aim to prove two +propositions: first, that there is such a process as evolution; +second, that he had discovered the method by which evolution is +accomplished. Before his time there was no general agreement as to the +fact of evolution. People generally thought the idea absurd, as well +as irreligious. All previous efforts on the part of advanced thinkers +to persuade mankind of the truth of evolution had been nearly without +effect. Among the early philosophers the whole idea was purely +speculative. They made no attempt to prove it, and the conception was +without influence upon the thinking of the ordinary man. This remains +true until the time of Lamarck. This French genius succeeded in +persuading not a few people of the validity of the idea of evolution. +He probably could have convinced many more had it not been for the +hostility of Cuvier. Accordingly, Charles Darwin's "Origin of +Species" fell upon a world entirely hostile to the idea, when it +thought of it at all. Within fifty years of the publication of this +wonderful book, probably the entire scientific world is agreed that +evolution, in some form or other, is the undoubted solution of the +mystery of creation. The materialist may think of it as a mechanical +process relentlessly working itself out without design or purpose. The +theist will accept it as the plan by which Eternal Power steadily +works. The devout Christian or Jew will see in it God's method of +creation. The idea of development has penetrated every science that +has to do with animals or man. It is even beginning to influence such +inorganic sciences as Physics and Chemistry. We now hear of the +evolution of the elements, and the evolution of forces. The world has +been persuaded that evolution is true, and this is primarily the +result of the work of Charles Darwin. It is astonishing that so great +a revolution should have come in so short a time. + +The other phase of Darwin's work was his attempt to find the agent +which is bringing about the actual transformation of animals and +plants. As we have seen in the preceding chapters, it was his idea +that natural selection was the efficient agent which constantly +eliminated all unfit variations, leaving only the best to carry on the +work of the world and to reproduce their own fit kind. Many +biologists since his time have doubted whether unaided Natural +Selection will account for the constant advance in organisms. This is +the part of the work which is often seriously questioned. + +Weissman and his co-workers have contended that this unaided principle +will serve. Most biologists have asked for some more efficient cause, +and assert that selection does not account for the appearance of +variations, but only for their preservation, and that any valid theory +of evolution must show how variations originate. It is chiefly in this +respect that Darwin's work has failed to satisfy many later +biologists. When we hear a scientist speak of Darwinism as being dead, +this is what he means. He does not think evolution false, but believes +that Natural Selection is not sufficient to account for evolution. +There are three main difficulties involved in Darwin's theory. The +chief defect lies in the fact that selection cannot originate +varieties. In all his earlier works Darwin simply accepted variations +as he found them. He was content to say that all species varied +constantly, and in every direction. He gave no theory to account for +variation. Whenever he took measurements of the dimensions of any +large series of objects of the same kind he found these measurements +to vary, apparently, in all directions. Upon the facts of these +variations, and without accounting for them, he built his own theory +of evolution. He realized his weakness, and acknowledged it in his +book. He probably did not anticipate how insistently later biologists +would demand an explanation that would account for this variation. In +his later work, responding to this criticism, Darwin originated a +theory which he called Pangenesis. He believed that when an adult +animal had responded to his environment and acquired a new character +he could transmit this character to his offspring. At that time no one +doubted this fact. The whole theory of Lamarck was based on the +assumption that this could be done. Darwin suggested that every organ +of the body threw off minute particles, which he called pangenes. +These little bodies, carried by the blood, were taken up by the egg +cells or sperm cells, and the latter cells determined the future +development. Consequently, the character of the new individual was +determined by the parental pangenes. In this way the gain acquired by +one generation could be passed on to the next. This theory was purely +speculative. He never pretended that there was the faintest +corroborating evidence visible to the microscope in the organ, in the +blood, or in the germ cell. It was not an accounting for what is, but +for what it seemed possible to him might be. + +This theory of Pangenesis, in the shape in which Darwin promulgated +it, has dropped out of consideration almost entirely. DeVries of +recent years has revised it, but with distinct modifications, and most +biologists pay no attention to it. + +There is a school of biologists, headed by Weissman, who have come to +be known as Neo-Darwinians. These men have insisted that Natural +Selection, if properly understood and developed, is quite sufficient +to account for the fact of evolution, including the appearance of +variations. Weissman himself is a microscopist of more than common +skill. He is thoroughly accomplished in the most modern methods of +killing, fixing, staining, and mounting. This worker's acquaintance +with the intimate structure of the cell is probably as great as that +of any other man in the world. Weissman asserts that he has seen +inside the nucleus all the machinery necessary to explain how the +father hands over his qualities to his children. He insists, equally +strongly, that this process is such that no father can hand to his +child any qualities which he himself did not have at least in +potentiality at his birth. Everything the individual acquires during +his lifetime is his own possession, which he may use and develop to +the utmost extent, but it dies with him. His children, born after he +possesses it, can no more inherit it than those born before. Weissman +expressed this in his famous statement that "There is no inheritance +of acquired characters." The biological world has had no shock equal +to this since Darwin's time, and there are few other questions to +which scientists to-day return with such constant vigor. + +If what Weissman says is true, that no variation or development which +comes to an animal during his lifetime can be transferred into his own +germ cells and handed on to his children, then it becomes evident that +we must find some cause of variation that acts within the germ cells. +This is the difficulty which Weissman meets. He says that there are +small particles in the nucleus of each cell; that these particles +which he calls determinants decide the form and the course of +development of that cell; that when that cell divides to produce +another cell it gives to this other cell one-half of each determinant. +As a result the second cell grows to be like the first. This tells us +why offspring are like their parents. There is nothing in the theory +thus far to show us why offspring are not exactly like their parents. +In other words, there is no accounting, thus far in the theory, for +variation. When the biologist studies carefully the history of an egg +while it is being formed, he sees that at one stage in its development +it throws away not one-half of each determinant, but one-half of the +determinants. When an egg does this, it deliberately casts aside +one-half of the possibilities of its own development. This throwing +away is quite as effective for all its descendants. Any ancestral +quality now lost is lost from the line forever. In the formation of +the sperm cell set free by the male a similar throwing away of +one-half the characters has taken place. The egg cell and the sperm +cell fuse together. There are as many possibilities now as there were +in either parent, but not all the potentialities of both parents. Half +the possibilities of each have been thrown away, and hence cannot +appear in the offspring. By this constant process we get, in every +generation, new combinations of qualities. This is the main cause, +says Weissman, for variations. + +There is, however, another possible cause. Each cell has enough +determinants in it for many individuals, and it seems to be more or +less a matter of accident which qualities shall come out. It has been +suggested that as an egg lies within the gland, a blood vessel may +bring blood to it in such way that a determinant, lying in a certain +position in the egg, may get the richest supply of blood, and hence +develop at the expense of the less nourished determinant. By these two +methods variation comes into an animal's life, if Weissman and his +school are to be believed. + +This is a serious blow, if true, to many theories of evolution. The +great mass of evolutionists still feel that somehow there is an +influence by which the environment produces variation. How the +influences of the surrounding world can get down into the body of the +parent and affect the egg is unknown. This is freely confessed by +every biologist. All are agreed that Weissman's work has made us +cautious, and prevented our lightly accepting a belief in the +influence of the environment. Yet it is felt by many that slowly and +gradually, in the long run, the germ is affected in the same manner as +is the body of the parent. In other words, even those who are not +followers of Weissman, have accepted the idea that there is little +inheritance of acquired characters. Yet they return to the belief that +somehow, in some way as yet unexplainable, the main cause for +variation in animals lies in the situation in which they live, and +tends toward better adaptation to that situation. + +Whether men with this conviction are merely reactionaries whose +confidence is returning, or bold thinkers whose views will ultimately +prevail, time alone can tell. + +A second strong objection was brought against the theory of Natural +Selection. Darwin declared that small variations in favorable +directions are selected and become the starting point of new and +better things. It is soon seen, however, that the effect of unaided +Natural Selection would be but to mix new departures with the old +forms, and soon swamp out any progressive tendency. Whenever a genius +appeared, instead of finding a corresponding genius with which to +pair, it mated with the average of its own species. Hence its +offspring were nearer the average than it was, and their offspring +still nearer. Thus whatever advantage the genius originally possessed +gradually sank into the common level. + +It was Moritz Wagner, a German naturalist, who first insisted that if +favorable variations were to amount to anything these possessors must +not only mate with others of their same kind, but must also be +prevented from mating with the old average group. Accordingly, the +belief arose that, under ordinary circumstances, variations returned +to the common level. Wherever a varying group became separated by any +barrier from mating with the rest of its species, and had only its own +kind to pair with, a new species sprang up. This barrier might be a +desert, or an impassable mountain range, an arm of the sea, or +anything else that the animal could not, or would not, cross. Isolated +in this way, the little group that had an advantage in a different +direction could develop its tendencies, and a new species would be +made of what had been previously only a geographical race. In this +matter of geographical isolation Wagner is very strongly supported by +the American zooelogist, David Starr Jordan, who believes that no two +closely related species of animals ever occupied the same geographical +area. Both Wagner and Jordan are ardent admirers of Darwin and his +theory of natural selection, but both believe that it is necessary to +add the idea of isolation in order to make natural selection +effective. + +George John Romanes, a British naturalist, has added to Wagner's idea +of isolation, the expanded conception that there may be isolations +that are not geographical. For this phase, Romanes has coined the term +physiological isolation. Something in the structure or habit of the +animals with the new variation prevents them from mating with the +older type. Occasionally it is a difference in the structure of the +reproductive organs themselves. This, however, is not the only +possible divergence. The mating season in one group may come earlier +than that of the other, or may come during the day, while the main +group is in the habit of mating at night. Anything which keeps some +members of a species separate in their mating from the rest, will +result in the course of a longer or shorter time, says Romanes, in the +formation of a new species. + +A third great objection was raised against Darwinism. The theory said +that only useful variations were selected by nature. It was asserted +by objectors that the earliest beginnings of any variation must be +too slight to be useful, or as the term went, to have selective value. + +It has been noticed by a number of naturalists that certain animals +seem to carry the development of a peculiarity altogether too far. It +is seen for instance that in the Irish Elk, which has for some time +been extinct, the horns were so enormous as to be a source of danger +rather than of assistance to their owner. It was said that the +tendency to produce heavy horns had gained, as it were, a sort of +momentum, and that this impulse had carried the development beyond a +safe limit. The Irish Elk became extinct because his horns were too +heavy. During the Mesozoic period the reptiles grew too large. They +seemed to have carried size to a point at which it became a danger +instead of a help. They completely passed out of existence, leaving +behind them only very much smaller reptiles. + +Eimer, of Germany, has based on facts like these his theory of +Orthogenesis. He says that variations in animals are not indefinite +and in every direction, but that they follow along clear and definite +lines. These lines, in the case of the elk and of the Mesozoic +reptiles, developed too far, but ordinarily the effect of such a +tendency is distinctly beneficial to the animal. It particularly +assists in carrying on for a time the variations which have not yet +become useful to the animal. It has always been difficult on Darwinian +principles to understand how the beginnings of the useful variations +could be selected before they were strong enough to be of actual value +to the animal. This tendency to variations in certain directions +instead of at random would account for such early development. This +theory of Orthogenesis has not figured very strongly in the history of +the movement, but it recurs at intervals. + +Both in America and France there is a constant tendency on the part of +zooelogists to return to the Lamarckian idea that it is the use of an +organ that develops it, its disuse that makes it fade away. This is +undoubtedly true of the individual, and although Weissman insists that +it is useless to the species as a whole, many zooelogists are slow to +relinquish entirely the idea that somehow these favorable developments +become reproduced in the offspring. + +Professor Cope, the American paleontologist, was a strong believer in +the effect of activity, both upon the individual and upon his +descendants. He believed that the insistent beating of the foot of an +animal upon the hard soil of the drying Tertiary plateau, had +influenced the production of a firmer nail, which spread around the +entire end of the toe and made the hoof of the ungulate. He believed +that the use of the teeth in grinding produced a stronger and better +molar tooth, and that the offspring shared in this advantage. Since +Weissmann's time, however, every Lamarckian feels it necessary to +suggest some method by which the altered body of the parent can +produce modifications in the germ plasms from which the young are to +spring. One of our later biologists begins to talk of some effect +comparable with wireless telegraphy or induced electricity. He +believes that organs in the adult, not necessarily by direct action, +but by action from a distance, may alter the germ. Of this, there is +no proof at present. Others have suggested that just as the ductless +glands pour into the blood chemical substances which materially affect +the growth and development of other portions of the body, so similar +enzymes, or other chemical substances, may be sent into the blood, +which subsequently bathes the germ cells of the coming generation and +produces the change. But of this, again, there is no proof. We may +believe that acquired characters are transmitted, but we certainly do +not have a very clear idea as to how it can be done. + +One of the strongest objections to Darwin's idea of evolution by +natural selection of small and favorable variations, is that the +process is too inconceivably slow to account for the enormous progress +which has been made. The answer has always been that our observation +ran back so short a time that we really have no clear idea of how +rapid evolution may have been. Again, it has been answered that +transitional geological periods, in which there is much change in the +physical geography of a country, will produce more rapid evolution +than we at present are experiencing. + +Hugo DeVries, of Amsterdam, believes he has found the answer to this +difficulty. Outside of his botanical garden an American species of +Evening Primrose had run wild. In looking over a number of these +plants he found, every here and there, certain peculiar members of the +species. They differed noticeably to the practiced eye from the rest +of the group. When they were planted and crossed with each other, and +the resulting seeds were again planted, the peculiarity remained +constant in all the members of the collection. Here then we have a +true variation, not large in amount, but at the same time quite +definite, and which from the first remains true. Here are the +beginnings, says DeVries, of new species. They are true from the +first; they can live among other members of the species and still come +true; they do not need isolation, at least in Wagner's geographical +sense. These forms DeVries calls mutations. It is his thought that a +species may run along uniformly for a long time when, from some cause +which he has not determined as yet, instability comes into the species +and it varies in quite a number of directions. Each of these +variations may be the starting point of a new species. DeVries +believes that he has at least half a dozen mutants of his new Evening +Primrose. + +This theory of Mutation has been eagerly seized upon by many +botanists. The zooelogists have not accepted it quite so +enthusiastically. If this is the chief method by which species +transform, it seems strange that we do not find more mutations than we +do. Perhaps we do not look carefully enough; perhaps we shall find +them a little later. Just at present it seems premature to believe +that all evolution is by mutation, although quite possibly some of it +is. The main apparent advantage of mutation is that it hastens the +time in which a new species may arise. + +There are certain difficulties which run back into the problem, and +which must first be reasonably solved before a clear understanding of +the idea of evolution is possible. The first of these is as to the +nature of life. What is life? The reply of the biologist will probably +be that so far as its material side is concerned, it must be answered +in terms of physics and chemistry. As to any side not material, if it +have any such side, science says that the chemist can have nothing to +say. The chemist may have an opinion of his own based on some other +ground than his chemistry, but so far as he is a chemist, he has no +opinion. The chemical side of life is being very carefully and very +fully investigated. We are certainly being brought nearer to the +borders of the living substance. We are rapidly gaining fuller +knowledge of the physical and chemical processes which constitute +life, or with which life is always associated. If we gain this +knowledge we shall be in better position to solve many of our other +problems. Even then there is a problem which preceded and which will +possibly always defy solution. How did life originate? Has it +developed out of chemical and physical activities which we know as +heat, light or electricity? If so, what were the conditions under +which it developed? If we understand the nature of life, and the +conditions under which it developed, we may be able to produce it at +will. + +A few scientists may hope dimly that this will be attained. I suspect +a great majority believe it to be impossible, and that the question as +to whether life evolved upon this planet, or this planet became +infected with life through meteoric dust from some other center, will +forever remain an unsolved problem. + + + + +CHAPTER X + +THE FUTURE EVOLUTION OF MAN + + +The disturbance of mind created by the publication of Charles Darwin's +"Origin of Species" would have amounted to nothing if the theory had +been applied to the lower animals alone. Few people would have +disputed that a cow and a buffalo had descended from the same +ancestor, or that monkeys and apes were of a common blood. The whole +theory would have been looked upon by those outside the biological +world as entirely an academic question, in which they had little +concern, and less interest. But within this century the scientist has +so persuaded the world of the unity underlying the activities of the +universe, that so soon as a principle is established men begin to run +it out to the very end. Everyone knows perfectly well that if it could +be proved that the dog and the horse had a common ancestor, still more +if it could be made apparent that the dog and the frog and fish had +sprung from the same stock, then there could be no question of what +would be the final application of the theory. Man himself could be no +exception to the law. So the battle dropped at once upon this most +interesting point, and around this center the contest has waged. + +What is the origin of man? Who are his ancestors? As soon as we ask +the question there is no doubt whatever as to the answer, if we accept +the principle of evolution. Our only means of judging relationship +between animals is by the similarity of their structure. As soon as we +come to examine the other creatures even in the most cursory fashion, +there is only one group which in any close degree resembles the human +species. Our nearest relatives among living animals must undoubtedly +be the apes. Some little distance farther away stand the monkeys, and, +structurally speaking, there is more difference between a monkey and +an ape than there is between an ape and man. The gap between man and +his relatives of this group, known as the primates, is a mental, not a +physical one. While his brain and his mind have developed far beyond +theirs, the rest of his body is comparatively close to that of an ape. + +Probably no one can face the possibility of his being descended from +creatures not unlike the ape, without feeling a stirring sense of +repugnance. The least aristocratic of us hesitates to name in the line +of his ancestry creatures so unlike himself as the members of this +group. It seems to us impossible that we should have descended from +creatures as lowly as they. If evolution is true, these are among our +near ancestors. Back of the group of primates lies a far less +developed set of insectivorous animals, behind them the reptiles, +behind them the fishes. When we get back this far we are less certain +but most probably the worms take up the story. So our ancestry runs +back to the very beginning, when it originated in the one-celled +animals which are also the ancestors of all the rest of the animal +world. If we are inclined to deny our ancestors in the trees, what +shall we say of our forefathers in the seas? + +The question of course is not to be decided by our likes or our +dislikes. If the evolution of man is true it will not make it less +true because the process is not to our liking. It is our part, if this +be the truth, to accept it as we do any other truth. Surely those of +us who are moral of thought are not willing to disbelieve a truth +because it is unpleasant. + +The newness of the idea is the chief reason for our dislike of it. +This lowliness of origin should not be distasteful to us. Nothing +about Abraham Lincoln seems to us more wonderful than that a man who +towered head and shoulders above his generation, indeed above most +generations of men, in his fineness of life, in his nobility of +purpose, in the integrity of his aims, should have been of +exceedingly humble extraction. It only adds to the glory of his later +achievements that he should have lived in a cabin, have spent his +young manhood splitting rails and running a flat-boat, and have gained +his education almost unaided from a few books and much meditation in +front of a log fire. + +That the greatest military General on the Union side of the Civil war +should have been the son of a country tanner, and as a boy, not +over-shrewd in the matter of bargains, adds to the glory of his later +life. The simplicity of his childhood gives new luster to the power +with which he led the forces of a nation to victory, and then went to +a battle no less noble in his long fight for honor while suffering +from disease and approaching death. Why then should we feel that such +beginnings in the lower world are too humble for man? Why do we think +his present superiority diminished by his lowly origin? Why can we not +see that precisely the reverse is true? The more humble the level from +which he sprang the more gloriously creditable is his present +position. Instead of being ashamed of having risen from the brute, it +should be the glory of man that he has so sprung. His chief +superiority lies in the fact that while they have remained where they +are, he has so completely outdistanced them as to have placed a gap +between himself and them that seems almost impassable. Furthermore, +if man with his present glory of intellect and of moral impulse, has +sprung from a creature whose superiority to the ape lay chiefly in its +potentialities, then it does not yet appear what he shall be. We can +judge the future only by the past. Through the long ages the +development has been very slow. Through the last hundred thousand +years the development of man has been wonderfully rapid, compared with +what went before, though it seems slow enough when we look at it from +the standpoint of our historical and traditional reports. But with +this added impulse, this rapid improvement that has come with the +development of mind instead of muscle, of tooth and of claw, we have +every promise of an evolution that shall far surpass anything that has +yet come. To-day our leaders are way beyond the average of the mass. +Who shall doubt that in a not too distant to-morrow, the masses shall +be where the leaders of to-day now are. We shall not then have reached +a dead level of superiority. Our leaders will have moved on as rapidly +as have the masses, and will be as far ahead of them then as they are +now. It shall be their work to apprehend new virtues, and to work them +out in their lives. The masses, seeing the beauty of the lives of the +leaders, recognizing in those lives the revelation of the divine power +which they have apprehended, will hunger to learn of them and to lead +lives like theirs. To this process who shall set an end? The advance +is slow, as in all evolution; but anyone who wishes to do so may +easily detect the direction of the current. + +The evolution of man's physical frame probably has nearly ceased. +Gradually organs that are useless to him are passing away. Slowly his +hands are becoming more delicate and refined and skilled. But his +evolution has begun to work itself out on entirely other lines. We +sometimes hear that the men of the past were the full equivalent of +the men of to-day. Scholars like to tell us that the population of +Athens was finer in quality than any population that has existed +since. We must remember that group after group of men may be expected +to specialize intellectually and fail to develop morally and +physically. Under these conditions this little branch of the human +race runs through its forced flowering and comes to an end. With the +study of history and the earnest investigation of these lives of the +past, new possibilities arise within the human family. The next race +that flowers may take longer to decay because it understands better +the weaknesses that carried away the preceding civilization. In time +there will arise a civilization that understands the past. A whole +people will some time realize that intellectual development alone will +not save it, or Athens would have lasted; that moral development +alone will not suffice, or Judaea had been permanent; that physical +development will not serve, or Sparta would stand to-day. Some day +there will arise a nation that will see to it that every intellectual +advance is accompanied by an equivalent moral and physical advance. +When this time comes we shall have a race which can survive. Are we to +be that race? The sins of man are generally the dregs of his brute +ancestry. Bestiality of life was once common enough to attract no +attention. Kings and nobles were not supposed to be clean so long as +they confined their bestial relations to those below them in rank. +Gradually men are becoming ashamed of uncleanness in life. Some day +there will be no difference so far as purity of life is concerned, +between the two who present themselves at the altar asking the +blessing of God on their union. + +If anyone doubts that English speaking people are becoming cleaner of +life he needs only to consult the literature of the past. No one +dreams of finding fault with Chaucer because his stories related in +the company of men and women often would not bear such telling to-day. +Shakespeare, with all his wonderful genius, needs expurgating if one +would read him aloud comfortably to a mixed audience. And these are +the shining stars. When we drop below them, the literature of their +time becomes nearly impossible to read. Fielding and Smollett and +Stern helped to build up the English novel, but the stories they tell +speak of the grossness of their time in language that is unmistakable. +We are by no means clean to-day. A fair proportion of our novels leave +much to be desired. The stage is the scene of much we could wish to +see cleaner. Above all this grossness there towers a sweetness and +beauty of thought, and an earnestness of purpose, a sincerity of +effort, which makes the present time fuller of moral purpose, fuller +of the desire to be clean and to help others to be clean, than graced +any previous period in the history of either England or America. + +Under the change from country to city life man has suffered. Here too +evolution is necessary. City life tells hard on the second generation +and nearly destroys the third; but we have come to understand the +difficulty and are fast remedying it. It is more than possible that +the next generation will see such changes in the life of the worker in +the great center, as shall effectively stop the physical deterioration +that has come to the city dweller. God grant that modern civilization +has had teaching enough and learned its lesson well enough. God grant +further that we may give over slaughtering our most ambitious and +vigorous young men in battle to settle questions which battle can +never settle. God grant that we have come to a turning of the ways +where the life of men, women and children, no matter how humble their +station, shall stand higher in value than the profits of any +commercial venture. God grant that we will soon be firm enough to +declare that a business which can only live by sacrificing the health +and strength of the workers must be counted an unprofitable business, +and be allowed to cease. God grant finally that the American people +may learn from the past to guard against a like fate in the future; +that here may be the people whose strength, intelligence and +uprightness shall lead the world; not for the sake of exceeding the +world, but with the high mission of setting to the world an example of +what can come to a vigorous, free and God-fearing people. + +In the early history of the evolution of man the struggle almost +always concerns the individual. Gradually the family comes to be the +fuller unit. Only that is success which leads to the success of this +higher group. After a time the family broadens to the tribe, and then +the tribe to the nation. The evolution of social institutions is at +present going on at an enormously rapid rate. Throughout the civilized +world democracy is coming to its own. Even where the form of monarchy +still prevails, the subjects of the monarch are having more and more +rights. The people of England are surely as free as are the people of +the United States. Increasingly all forms of government will secure +for all their subjects, no matter what their station in life, a fair +share of the general prosperity. In this field, human evolution is +perhaps more rapid than in any other. + +Any individual human being is a network of traits and peculiarities. +He has all the ordinary attributes of humanity, but to the whole +complex he gives an individual peculiarity which is totally his own. +Where did he get his qualities? In the earlier times the fairies were +supposed to have blessed him or cursed him in his cradle. A later age +saw in the stars the rulers of man's destiny. He was jovial, or +saturnine, or martial, depending on the planet which was in the +ascendant at the time of his birth. Now we know "it is not in our +stars but in ourselves that we are underlings." Everything a man is +comes to him from within or from without; from nature or from nurture; +from his heredity or from his environment. From our ancestors we get +all the possibilities of our lives. To a certain extent we are slaves +to our heredity, but not by any means to any such extent as to make us +hopeless, unless our heredity is miserably bad. To the great mass of +us come larger potentialities than we ever develop, and such +possibilities of degradation as, fortunately, few of us ever reach. +Within an enormously wide range, man is the architect of his own +fortune. Only such traits develop as find a stimulus in the +environment. Accordingly, a very large proportion of the development a +man may achieve depends upon the circumstances under which he is +placed, or, what is far more to the point, in which he may place +himself. Man is not the blind sport of a relentless destiny. It is his +to choose his environment; it is his to modify his environment when he +cannot leave it. To an extent which no other animal has ever +approached, man is the arbiter of his own destiny. A hypothetical ass +may stand helpless between two equidistant bales of hay, but no human +being is ever so helpless a sport of his environment. As it is, he may +drift or he may rove as he pleases. To one man the current may be +stronger than to another. There may be now and then a child so +feeble-minded as to be unable to decide the course of its own life. It +will not be long before society will see to it that such a life leaves +behind it no strain cursed with its fatal weakness. In this effort to +advance, man has all the advantage that comes from concentrated social +effort. No man may live to himself. To every man in our community who +desires it, a helping hand will be stretched. Often a hand will be +stretched to him and he will be steadied whether he will or not, +until his own will reforms itself and gains the mastery. + +Inasmuch as all that is in man comes from his environment or from his +heredity, the only way in which the race of men can be advanced is by +improving their environment or by bettering their heredity. The first +of these is the province of the sociologist; the second that of the +eugenist. The sociologist has for some time been giving his careful +attention to the improvement of the environment. In every large city, +a man must build for himself a house fit to live in, if he build it at +all. Whether he erects it for himself or for another makes no +difference. Society will no longer allow him to build a home which is +a detriment to the one who lives in it. Not only must he make himself +a decent home but he must keep it in decent condition. The community +will not allow him to endanger his own health, or that of his +neighbor, by an insufficient method of attending to his garbage, or by +a lack of ordinary cleanliness. If he will not clean his premises +himself, the law sees to it that they are cleaned for him. Already we +are beginning to understand that no man has a right to employ another +man or woman or child at wages which are not sufficient to maintain +the one thus employed. The wages of many people are exceedingly +meager, notably those of women and children. He can read but ill the +signs of the times who does not foresee an early end to the exploiting +of the labor of these helpless creatures. Humanity has determined +firmly that these things must pass, that the young child must not +labor long or hard, that a woman must not be taxed beyond her +strength. Already in England there is a partially successful movement +which will doubtless spread to this country to provide that a woman be +granted a little time before and after the birth of her child during +which she shall not be allowed to suffer because her power to earn a +wage is temporarily gone. These things cannot fail in the long run to +strengthen the people. They strengthen chiefly the present generation. +The blight of the fact that acquired characters cannot be transmitted, +meets us here. This improved environment can only slowly, if at all, +improve the race, and every effort made in this direction must be +repeated with each generation. + +Under such circumstances is it to be wondered at that the eugenist is +hoping to raise the strain? Any improvement he can bring about is not +only valuable for the generation in which it comes but is carried on +into the generations which follow. This is the hope that strengthens +and sustains him in his effort. The science of eugenics is so new, so +little is surely known concerning the transmission of human +characters, that no one is able as yet wisely to say what course is +to be pursued in improving the race. But the problem is so interesting +and its outcome so overwhelmingly important that men will never cease +striving to know, and may, before many years, begin wisely to guide us +in our efforts to provide a finer stock. + +Heretofore our efforts at improving the strain have been confined to +cattle, chickens and plants. An almost unalterable repugnance rises as +soon as we speak of improving the human strain. Visions, if not +stories, start up at once, of experimental matings of human beings, +and of all other unspeakable abominations which no decent man expects +to happen or even wishes to attempt. If there is one thing in human +society the value of which has been demonstrated through the unending +ages, it is the monogamic marriage. All ideal workers must point to +the life-long union of a strong, vigorous, clean-minded and +clean-lived man with a similarly fine, strong, clean-minded and +clean-lived woman. Such an ideal may be slow in its attainment, but he +aims too low who aims to secure anything less than this. The long +struggle out of bestiality into pure monogamy has been so slow, so +gradual, so noble in its attainments, and is still so far from +perfection, that it would be an inconceivably stupid blunder to let go +a single point that has been gained. Whether divorce shall be allowed +to remedy a mistake may be a matter of dispute, but at best it is a +bad remedy for a mistake that should never have been made. No ideal +society could ever consider divorce as any permanent portion of its +activities. Children are not like cattle. It is not simply a question +of their being brought into the world sound and strong. Their long +infancy which in the biological as well as in the legal sense, lasts +until they are grown up, should be spent in surroundings which can +minister, by example and precept, to moral and intellectual +development. Surely no such end can possibly be attained when man and +woman mate lightly, to part quickly. + +At first sight it would seem a wise thing to require health +certificates for those who would be married. I doubt not the Chicago +Bishop who declined to marry his parishioners except under such +conditions, will exert a beneficial effect upon the country by the +attention he thus attracts to the subject. It would be a bad day for +the city if all the clergy and all the other authorities who are +authorized to solemnize marriage should take this step. We have not +yet arrived at such a stage of development that a marriage certificate +is essential to mating, and a restriction of this sort would simply +mean that there could be no legitimate union except of those in strong +health. To the burden of ill health would be added the still worse +handicap of an illegitimate parentage, with all its bitter train of +scorn and shame. Accordingly, it must be possible before the law for +those who are not thoroughly vigorous to marry. But, year by year, we +may come nearer accomplishing a finer mating by the aims and purposes +we foster in the growing generation. Marriages will never be worth +while when they are not freely entered into by the contracting +parties. Choice must be free and unrestricted if it is to last for +life; but this does not mean that it must be unguarded. It would be +bitter folly for parents to leave to their children, without attempt +to influence or restrain, the making of their marriages. The mating of +our children must be inspired, not directed. + +There is one taint from which society has the right and the duty of +freeing itself, so far as in its power lies. This is the taint of +feeble-mindedness. Of all the calamities that can befall a human +being, feeble-mindedness is, perhaps, the worst. From most misfortunes +it is possible to recover; with most of the rest one may exist without +detriment to the race. To be feeble-minded simply means to hark back +to the level of our animal ancestors, without regaining their power to +guide life. The animal is provided with a bundle of instincts which +tell him what to do in all the ordinary emergencies of life. The +human species, in its development, has lost a large portion of its +instincts, and has gained, instead, the power of intelligent choice +and the ability to learn by imitation. When these drop away, man +without his instincts or his intelligence is more helpless than the +brute. Students of sociology are making clear to us that a large +portion of the criminality of the world, much of the looseness of +life, and a large part of the alcoholic excesses are due to this taint +of feeble-mindedness. Recent investigations have made it clear that +one feeble-minded family in a community may, in the course of years, +poison the life of an entire state. The Jukes family in New York, the +Kallikak family in New Jersey, have shown the awful possibilities of +descent from a single feeble-minded ancestor. Prisons, almshouses, and +houses of shame owe their population in no small degree to this bitter +curse. It will not be long before society will learn to protect itself +against such poisoning of the human stock. Nothing is more clear to +the investigator of this subject than that the one overwhelming cause +for feeble-mindedness is feeble-mindedness in the parentage. + +There is one type of mental weakling, known as the Mongolian idiot, +which may arise right out of the heart of an apparently sound family. +But the number of these is comparatively small. The number of +feeble-minded, who are feeble-minded because of their heredity, is +dishearteningly and astonishingly large. Every attempt to examine +large numbers of school children shows a sickening proportion of those +who are distinctly feeble. Every little community seems to have its +boy or girl who is what is known as silly. Such people rarely live +long lives without leaving behind them feeble-minded children, no +small proportion of whom are likely to be illegitimate. Against this +fouling of the stream at its source, society must protect itself. +Legislators revolt at the somewhat inhuman but certainly safe method +of surgically preventing the possibility of the feeble-minded becoming +parents. It would be more creditable and just as effective if society +would take upon itself the tremendously expensive task of caring for +all its feeble-minded in institutions during their entire life. The +cost would be large for a generation, but would rapidly diminish and +eventually become small. It certainly would be the humane way. These +people in good institutions are by no means unhappy. Within the limit +of their capacities they can do many things. Wise management usually +will secure from them labor enough of wholesome and simple kind nearly +to pay for their own support. Nothing could be better for them than to +till the soil, care for the cattle, tend the chickens, and, in this +way, provide very largely the materials on which they are fed. How +this problem shall work out, time only can decide. With it once worked +out, there is no doubt that the level of humanity will be distinctly +raised. No other one feature in the program of eugenics seems more +absolutely hopeful than this. + +In several of the states of the Union it has recently become the +practice to remove the possibilities of parenthood from certain +classes of criminals. The purpose of this is clear and benevolent. +Society has a right to prevent the oncoming of new generations of +foreordained criminals. Underlying the practice is the theory that the +children of criminals are born criminals. It is far from likely that +this is the case. Criminality may be due to a wide range of causes. If +the criminal is one of those actual born degenerates whose whole +mental and physical make-up is so defective that nothing but +criminality can be expected of him, then we have a case in which it is +clear that society may, and should, remove the possibility of having +more generations of the same kind. Probably only a moderate proportion +of the criminals in our jails and penitentiaries belong to this class. +Doubtless a distinct majority are criminals more through environment +than through heredity. Born of average ability, or more, these people +have been criminals simply because they were reared among criminals, +because their surroundings were such as to lead them away from habits +of industry, while they must live. These people were not bolstered by +society, or the church, into a life of self-respect and self-help. +Under these circumstances they fell into evil ways. There is nothing +defective in their mental or physical make-up, that need appear in +their children. If these children are removed from contact with the +criminal class they stand every chance of being as vigorous, as +intelligent, as upright as the average of the community. + +At the recent Eugenics Congress in London one of the speakers +expressed a preference for the son of a husky burglar over the son of +a tuberculous bishop. This is doubtless quite correct, but why should +the bishop be tuberculous? The truth of the matter is, the reverse is +more likely to be the case. Personally, I should prefer to be the +offspring of a husky bishop. In dealing with criminals, then, with a +view to cutting off their posterity, we must be careful to understand +whether we are dealing with a hereditary or an acquired criminality. +If there is a genuine hereditary criminal taint, society is right in +freeing itself of it. If it is acquired criminality, then it is not +transmissible, and the offspring, if placed in a good environment, are +likely to be good citizens. All of which means that, until we are +clearly sure of what constitutes a hereditary criminal trait, we +should move very slowly in the matter of mutilating criminals. + +What steps may the eugenist, with his present limited knowledge, +clearly, hopefully and confidently take to improve the future of the +human species? There is one avenue open to us in this matter in which +we can hardly go wrong. Even our mistakes can work little harm, and +every well-done piece of work in this field will be a blessing to the +race. This step lies in inculcating in our boys and girls high ideals +of parenthood. This is more effective than legal prohibition of +certain forms of marriage which cannot prevent matings, and adds the +curse of illegitimacy to the other handicaps of the children of such +unions. The first step in this process has already been reasonably +well accomplished. Both our boys and our girls are in love with +health. A good husband and a good wife should be healthy and vigorous. +This does not mean that we expect a boy or girl who is looking forward +to marriage to sit down and ask himself deliberately about the health +of the person with whom he would mate. We must fill our children with +the love of outdoor life, with the love of exercise. This will foster +in them an admiration for people who are vigorous of body and alert of +mind. It ought to become practically impossible for a hearty and +vigorous boy to fall in love with a helpless and anaemic girl. It +should be equally impossible for a hale and active girl to admire a +man who was her inferior in either vigor or alertness. The modern +taste for outdoor life has largely brought this to pass among such of +our people as have leisure enough to indulge in vigorous sport. Among +the crowded dwellers in the closer sections of the city such life has +been so nearly impossible that no ideal of vigorous manhood or of +radiant womanhood has had a chance to grow up. With the oncoming of +the parks and play-grounds, all of this, we may hope, will change. +Health and vigor will be no less attainable and hence no less adorable +in the city than in the country. Rich and poor alike will be attracted +by rosy cheeks and an elastic gait. + +Our aim, however, should not cease with a vigorous body. We must teach +our young men and young women the glory of a well disciplined mind. +This should seem quite as admirable to them as a vigorous body. To +them, straight thought ought to be as lovable as a firm and supple +body. In this matter our young people are less exacting. The ordinary +conversation of people gathered together for social purposes is not +particularly intellectual, and any attempt to make it so at present +seems priggish. With a broader education, will come keener demand for +intelligence. We may hope the time is not too far distant when a +question of governmental policy, a new book or play, or a new +discovery in science will stimulate as much conversational zest as now +seems to be gotten from a pack of cards. + +A third feature of the ideals which should be instilled into the minds +of our children is the moral phase. There seems little doubt that this +is on the way. We must not mistake an evident laxness of religious +observance as being synonomous with moral looseness. The revelations +which our recent periodicals have brought us concerning the habits of +business men, of politicians, and of society, have left on many minds +the impression that this is distinctly an age of decadence. Exactly +the reverse is the truth. This is the age of intense sensitiveness to +wrong. In almost no particular is it worse than any previous age in +the history of our country. We openly discuss things which we left +untouched a little while ago. We insistently demand that business +practices to which nobody particularly objected a dozen years ago must +now certainly cease. All of this has produced an erroneous impression +that the times are out of joint. But the dust and dirt in the air is +the unavoidable accompaniment of house cleaning. When doubtful +practices simply have publicity many are awakened to the sense of +their duty to society. Persons who, of themselves, might be willing to +live low and godless lives, dare not do so in the face of society when +our social ideals are finer. I believe there is the utmost hope that +within two generations our young men and young women will scorn +meannesses which we are accepting with entire complacency. + +A close acquaintance with thousands of young men and young women +running through an experience of twenty-five years has taught me to +believe that our young people of to-day are altogether cleaner of +mind, of tongue, and of life than were their parents. There is freer, +franker discussion of many things that their parents would scarcely +have dared mention, yet I feel sure the moral tone is distinctly +higher. I look with entire hopefulness to an early season when the +young man who asks a woman to share her life with him will be met with +the entirely proper question, "Have you kept your life clean for this +event?" I believe that unless the answer can be in the affirmative the +young woman will not be able to have admiration enough for the young +man to cover uncleanness in his life. + +There is one temporary phase of present life which seems discouraging. +The increase in the cost of living, and still more rapid increase in +the standard of living is shifting too late in life the age at which +our young people marry. The result is that one of two things is likely +to happen; either a large number of people are likely not to marry at +all, or the romantic time of life is passed before the event occurs +which it is intended to bless. A young man and young woman who are in +this time of life can deny themselves for each other, can struggle and +plan together, can hope and trust together to an extent that can never +be the case if marriage is delayed beyond the romantic years. + +The best foundation possible for a life of happiness is vigor, ability +and good character. For the lack of none of these can wealth properly +atone. + +There is an apparent tendency to waken to the situation. I hope it +will come soon enough for our young men and young women to get past a +desire for such establishments in life as their parents already have. +With this difficulty removed, with our widespread education, with the +constant diffusion of both information and ideals from our periodical +press I have every hope that the evolution of a new, a finer, and more +vigorous race, will come with a rapidity which nothing that the past +has done would lead us to expect. + + + + +CHAPTER XI + +SCIENCE AND THE BOOK + + +We of the twentieth century have an overwhelming desire to be up to +the times. Nothing but the latest news on any subject will completely +satisfy. We are more anxious for late information than for accurate +information. We have an almost unconquerable feeling that if it is +late it must be accurate. All of us are sensitive to being thought +behind the times. We feel that no stigma can be more invidious in the +intellectual world than the stigma of being out of date. This pervades +the masses quite as strongly as it does the more cultured classes. +Under these conditions everybody wants to know the latest theory that +science has to offer concerning anything that can be brought within +the range of their interests. As a result everybody would like to know +about evolution, were it not for the fact that a great mass of people +have been brought to believe that there is something inherently +irreligious in the idea. Our people have a saving sense of the value +of religion. Denominational control may set lightly upon them. +Certain long revered doctrines may have little practical influence +upon them. Yet inherently they all believe in religion, and most of +them believe themselves to be religious, as indeed they really are. + +It is a most wholesome tendency which leads us to esteem religion as +the main interest in life. We must feel a sense of shame when we +consciously permit the influences, which most favorably mold our +character, to weaken their hold upon our lives. Certainly in our time +religion is the essential agent by which character is molded. Any of +us would be foolishly short-sighted were he willing to weaken the hold +of religion upon his life for the sake of a scientific theory, the +truth or falsity of which could have but little practical bearing upon +his conduct. We must hold to religion at all hazards. We may, when +circumstances so suggest, change our denominational allegiance. We may +and often do interpret our faith quite at variance with the +ecclesiastical body with which we are connected. We may constantly +modify and develop our beliefs. But it is a pitiful life which has +lost the staying and strengthening influence of religion. I believe +this conviction is deep-rooted in the minds of our people and that it +deserves the place it holds. + +To a mind thus essentially religious the announcements of science +often come as a shock. They seem to run counter to our deepest +convictions. It seems impossible to us that both can be true. +Sometimes the more we debate the questions the more contradictory they +seem to become. Every good mind needs unity in itself. No clear +thinker can be quite content when two distinct departments of thought +are at sharp variance in his mind. He may pursue one of two courses. +He may hold to one view with conviction and earnestness and look upon +the other as essentially false. To many religious people all science +that runs counter to their convictions is necessarily false. They +label it pseudo-science and pass it by. If the word pseudo-science is +unknown to them, they stigmatize it as rationalistic, or still worse +as materialistic and let it go at that. + +The other course is to have faith both in religion and in science. + +Such a fair-minded man must ask himself, what is the truth in the +matter? If the scientific fact is true it is to be believed. It may +run counter to what we have believed before. It may seem at first +entirely incredible. But when once he becomes convinced of its truth +the clear thinker must not only accept it, but must accept all +legitimate deductions from it. If it seems true to us we must believe +it. Absolute demonstrable truth, except in the simplest of matters is +almost unattainable. The best we can ordinarily get is a close +approach to certainty, and with this we must be content. In many +matters, indeed in most matters, we must trust the judgment of others +who are better trained in a particular line of thought. + +As to the truth of geology we are certainly wise to accept for the +present the facts and principles commonly accepted by competent +geologists. In biology, we should respect the concurrent opinion of +important biologists. We must not assume that a few biologists who +think as we do are right against the biological world, or that a few +geologists who think as we do are right against the geological world. +For theology, we had better go to the educated theologian. But when it +comes to reconciling two of these and to catching the inherent +correspondence between them, it is often likely that each of these +groups of men is unable to see clearly the view-point of the other. +Here lies our freedom. Here we must either think for ourselves or +think with those wiser than ourselves whose opinions seem to us to +ring true and to focus for us our wavering and uncertain thought. + +Among students of animals and plants there is no longer any question +as to the truth of evolution. That the animals of the present are the +altered animals of the past, that the plants of to-day are the +modified plants of yesterday, that civilized man of to-day is the +savage of yesterday and the tree-dweller of the day before, is no +longer debatable to the great mass of biologists. To older men +hampered by the convictions of an earlier age this dictum of modern +science may still be a little uncertain. + +The working biologists of the world have no doubt. They differ +radically as to what brought about this change, they dispute +vigorously as to the rate of change, but as to the fact of the change +there is no difference of opinion. Under these conditions the thinking +man is out of joint with the times when he sets himself against the +idea of evolution. He may be so immersed in other lines as to be +indifferent to the problem; but when he is hostile to it, he marks +himself as clearly against his day. Many have been against their day +and have been right. Very great men have often been against the +opinions of their times and have come to be leaders of the world's +later thought. But ordinary men in ordinary times who think +differently on a special subject from the specialists of the times are +not very likely to be right. It is safe for most of us to accept as +true an opinion on which specialists on that subject agree. It seems +clear to me then that the thinking man to-day has in the matter of +evolution a double duty. He must become reasonably acquainted with the +theory that so largely affects all present knowledge, and he must +wrestle with the theory until it no longer hinders the hold of +religion upon his life. He may be perfectly sure that he does not +clearly understand both, but he must get them into reasonable +concordance before he can be quite at peace. + +Truth is true no matter how it is acquired. There can be no doubt as +to the essential truth of religion: its fruits proclaim its worth. +There can be no doubt as to the essential truth of evolution; the +clarity it has brought into the sciences is the evidence of the value +of the conception. That it will persist in its present form, that it +will be unchanged by later additions to our knowledge is of course +unthinkable. It may be incomplete, it may be undeveloped, but so far +as it goes it contains the truth. Under these conditions, how can we +bring peace into our own mind? These two important provinces seem so +often to be at variance. The difficulty may lie in one of two places. +In the first place, each truth may be stated in terms so peculiar to +its own subject as to convey no meaning to the student of the other +branch. There is a second, and more harassing possibility. The same +words may be used by students in each branch but each side may put a +different significance into the terms. Then each believes he +understands the other, when he really does not. + +Our theology is man's interpretation of God's revelations of Himself +as recorded in the Bible. Our science is man's interpretation of God's +revelation of Himself in nature. Each is God's revelation, and so far +as we have understood it, that revelation is of the utmost importance +in our lives. Each has all the inherent short-comings of man's +interpretation. Each has all the difficulties necessarily found in any +stage of a developing understanding. We may be sure if we could +thoroughly understand God's revelation of Himself as recorded in the +Bible and his revelation of Himself as recorded in the rocks and the +tissues of animals as well as in the body and mind of man to-day, +there would be no difficulty. When we understand both completely, as +perhaps we never shall, there will be no contradictions of any kind +between them. Even now if we are firmly convinced that truth must be +in both, there will be little difficulty in reaching a workable unity +which will satisfy the present needs of the human mind and will not be +so crystallized as to prevent a future growth. If, however, we hope to +find a unity between a belief in evolution and a belief in the +inspiration and value of the Bible, we must accept both of these in +the terms of to-day. To reconcile a twentieth century statement of +science with an eighteenth century statement of theology would be as +absurd as it would be to reconcile a statement of twentieth century +theology with eighteenth century science. Each century must restate +its truths in terms of its own time. The truths may be at bottom the +same through many centuries but to be clearly intelligible in any +century they must be couched in the terminology of the age. + +It seems to me if we are to understand, in conformity with the thought +of the age, any particular book in the Bible, there are three steps +through which we must pass. We must first ask ourselves the kind of +people to whom the book was originally written. We must know their +habits of life and of thought. Until this is clear in our minds the +book can have little significance. Having built up as nearly as may be +the life and thought of the time, we must next decide what is the +inherent truth taught to the people of that time by the book under +consideration. Much that is written must be simply the setting in +which alone that truth could reach them. This extraneous detail gives +vigor and color to the message but is not the message itself. The last +step and the hardest one to take, the one that to some minds seems +almost irreverent, is to decide the form that message must take to-day +to convey to our minds the same truth which the original message +conveyed to the people of its time. In so far as we succeed in taking +these three steps, we shall get the true message which this book +holds for us to-day. + +When Paul in his first burning letter told the Corinthian congregation +that their women should be silent in their churches, he is not, it +seems to me, giving a message which in those terms applies to the +world to-day. If a woman has anything that is worth saying she has a +perfect right to say it in church. In any denomination in which +religious observance is not ecclesiastically formal she will be +allowed that privilege. By an interesting peculiarity of mind on our +part she may be permitted to do so upon Wednesday evenings, when our +early prejudice still prevents her speaking on Sunday. What is the +truth of the teaching of Paul in this matter? The Christians of +Corinthian times had already begun to suffer from persecution. They +were already despised and distrusted. Men had come to speak ill of +them. Paul's injunction concerning the silence of women in churches +was simply an injunction against their doing those things which in the +thought and habit of those times were associated generally with +looseness of character. Fine Corinthian women did not speak in public. +A woman who would consent to speak before a group of men of Corinth of +that day would by that fact have proclaimed herself a woman of loose +morals. Paul's injunction is that, in this desperate struggle +Christian women should do nothing which could possibly bring them into +disrepute. The lives of Christians must be above suspicion. This +message is certainly as true to-day as it was in the time of Paul and +Corinth. Whether or not a woman speaks in church to-day has no bearing +whatever upon the question. The question is how she speaks and what +she says. If her life gives force to her message and her message +contains God's truth she is entirely free to speak. + +In similar fashion we have changed most beautifully the message which +we have come to love, as the Mizpah message: "The Lord watch between +thee and me while we are absent one from the other." We have +absolutely transformed and glorified the message. It was once the +calling down of the wrath of Jehovah upon one or other of two herdsmen +if either of them should fail to comply with the agreement to remain +within his own boundary. These men whose herdsmen were constantly +stealing each other's cattle agreed to separate because they could not +live in unity. They set up a heap of unhewn stone, and called upon God +to guard and to see that neither of them passed beyond the boundary of +the other. What was once a threat between warring herdsmen has become +a binding link between Christian brothers. No longer do we call upon +the Lord to guard in our absence lest our enemy encroach upon our +domain. Now we call upon him to bind our hearts together so that +neither time nor circumstance can bring division between us. The +menace of a herdsman's wrath has become one of the tenderest messages +of Christian love. + +In the light of the principles stated above, what is the essential +truth that lies back of the earliest chapters of Genesis? First, that +there is one God. Slowly it had been borne in upon the Hebrew mind as +upon no other tribe in the world that the Lord God is one God. Nearly +all the world besides believed in many gods. Each nation had a God +peculiarly its own, each city had a minor god caring for it +particularly. There were gods of the woods, gods of the oceans, gods +of the streams. Gods and goddesses were everywhere. To this people +wandering through the terrible monotony of the sandy desert, the +"Garden of Allah," there came the inspired comprehension of the +eternal oneness of Almighty God. First, he was to most of them the God +of the Hebrew, stronger than the gods of the nations. After a while +under the teaching of prophet after prophet there finally came to the +entire nation the exalted conception that God is one and there is no +other God. This is one of the imperishable revelations of all time. +Beside this, all suggestions of fifth or sixth day, of hours or of +ages are absolutely insignificant. These are but the clothing of the +idea which makes it acceptable to its time. This clothing must change +with every age if it would reach thoroughly the minds of the age. +Underneath and forever lies the glorious truth that the Lord God is +one God. + +The second truth which seems to me to underlie this magnificent +parable of creation is the truth that this great God has created the +universe and that he cares for his people. Gods before had been +objects of terror. Gods before had lived lives such as the people +themselves would not have respected among their companions. Gods +before were to be shunned. If one could but escape the attention of +the gods it was his greatest good fortune. Now we have the conception +of an all-knowing, ever-present God to whom his people are dear. The +terms in which it was stated in those days matter but little. To +modern psychologists even the idea that people are dear to God seems +speaking too humanly. Yet the truth involved must come in terms that +the people of to-day understand. We can best comprehend God if we +think of Him as loving and chastening, even though down in our hearts +we know that these terms are not high enough, are too human to apply +to an Eternal God. But we know no better and they tell us the truth +even though the terms may in time pass completely away. + +Last of all and perhaps most characteristic of the Hebrew people is +the great lesson that this Eternal God, who created the universe and +cares for his people, demands righteousness of his people. To the +nations round about religion was not a matter of righteousness. For +them religion had nothing to do with morality. Thieves might have gods +favorable to them quite as well as righteous men. The worship of Diana +of the Ephesians or of Astarte in the groves of the Asia Minor coast +could be so unspeakably licentious and vile as not to admit of +description to-day. Yet this was all religion. To the Hebrew came the +inspired, exalted conception of a God who demanded righteousness of +his people. Beside this wonderful revelation to the human mind details +of serpents, and of apples, of names of men and of women, of gardens +and of swords are absolutely but the transitory clothing. This brought +them to the minds of the times. The value of the form is evidenced by +the fact that it brought the conception. But we must not lose the +glory of the conception in an over regard for the clothing in which +the idea came. + +Does this mean that Genesis has served its purpose and is to-day to be +conceived of as a beautiful relic of the past, to be reverently +enshrined but not seriously accepted? Far from it. The glory of the +Genesis story lies in its wonderful power to grow. It strengthened +the minds of a persecuted tribe wandering in the desert who finally +settled in a small and barren country. It brought the truth to them so +clearly that they have persuaded much of the world of that truth and +bid fair to persuade the rest. The story has grown with the mind of +man. As it served the Hebrew in his time it has grown to serve others +to this day. Each generation has read the story in the light of its +own times and each generation will continue to read the story in the +light of its advancing knowledge. The only part of the story that can +be affected is the clothing, the inherent truth remains forever. +Furthermore, the story which persuaded the childhood of race is the +story which will persuade the childhood of to-day. In no other form +could the great truth of the Bible be brought to our children as well +as in the form of these early chapters. In early life our children +will accept these stories as literally as the ancient Hebrew accepted +them. As they grow in knowledge, unconsciously and without jar, if we +do not jar them, our children will read into the story what God has +taught them in the world outside. The shock which came to their elders +need never come to them. It is our fault if our children are disturbed +by the conflict between religion and science which disturbed us. There +is no difference between God's revelation of Himself, as we have it in +the Bible, and God's revelation of Himself in nature. The better we +know the Bible and the better we know nature the clearer this will be +to us. + +Perhaps the most severe shock that has come to the mind of religious +man from the teachings of science has been the at first almost +unsupportable idea that man is the descendant of creatures of which +the ape is to-day the nearest representative. He had learned from +Genesis the altogether adorable conception that he was made in the +image of his Maker. It lifted him; it strengthened him; it gave him +more power to struggle. He might know that he had marred that likeness +by wrong-doing, he might understand that the fullness of the glory of +God's image could not shine through his own face. Yet he believed that +he was, in spite of all his imperfections, made in the image of his +Maker. Now comes this horrible linkage with a miserable brute to +either shock and confound him or to degrade him. We can easily +imagine, some of us have bitterly experienced, the shock of this +changed conception. But it was only because we mistook the clothing +for the truth in both cases. We read science in its own terms; we read +Genesis in its own terms. They did not use the same language and they +jarred us to the very soul. Slowly, however, we are coming out of the +darkness of that battle; slowly the glorious light of the beautiful +truth is breaking into our minds and our hearts. + +Michael Angelo painted a wonderful picture of "The Judgment." Here, +seated upon a throne, which after all is only a magnificent chair, +sits a venerable figure of what is really but a nobly-proportioned +man, to whom the nations come for their final reward. He separates the +righteous from those who must forever be sundered from their God. Seen +through the distant past it still remains a majestic picture; but no +painter would think of repeating its conception to-day. + +Quite in the modern spirit is the beautiful lunette which John Sargent +placed in the Boston Library, above his well known frieze of "The +Prophets." It represents "Jehovah confounding the gods of the +nations." The naked figure of suppliant Israel stands before an altar +of unhewn stones, on which burns the sacrifice. The smoke ascends to +Heaven. On one side stands the mighty figure of Assyria with uplifted +mace ready to strike its awful blow upon the shoulders of helpless +Israel. On the other side the lithe, subtle form of Egypt, clasping +the knout, watches its chance to bring its treacherous thong upon the +helpless shoulders of suffering Israel. But Jehovah may not appear, +man may not look on God and live. Jehovah is seen as a glory behind +the cloud of smoke shrouded by winged cherubim. From one side of the +cloud comes a mighty hand meeting with power the force of Assyria. +From the other side, a lithe and sinewy hand thwarts the subtlety of +Egypt. But Jehovah is behind the cloud. + +Again we understand that we are made in the image of our Maker. Again +we understand the power of the uplift of this idea. From the conflict +it has emerged in new and glorified form. Hath a God eyes that he may +see? Hath a God ears that he may hear? Hath a God hands that he may +work? These we know to be but human forms of speaking. Eyes, ears, and +hands we may owe to the brute from whom we have sprung; in our eyes +and ears and hands we show the relationship we bear to them. These are +not the image of God. God is a deeper, a finer, a nobler something +than hands, than ears and eyes. The image of God lies within +ourselves: the image of God is that which makes us what we are. In +every noble purpose, in every earnest endeavor to uplift ourselves or +our fellowman, in every thought that turns us from the evil of a +repented past, in every desire with which our hearts yearn to +strengthen, support and sustain our friends and even our enemies, +shines forth the image of Almighty God. This it is that links us with +the Eternal: this it is that makes it worth while that we should be +Eternal. Besides this what are hands and ears and eyes? We are made, +all in us that is noblest and highest, in the image of our Maker. + +A word in closing. The time is ripe for a broader conception of +theology and of science on the part of those who are not trained to be +specialists in either. We are becoming more and more inherently +religious. We are becoming more and more enamored of the truth in all +its forms. The times are ripe for us to cease the struggle and to +strive for peace. So long as men insist that the important things in +faith are the things on which men differ there will be eternal strife. +So soon as men endeavor to find the common ground between them and +each tries to state his belief in forms acceptable to himself but +involving no hostility to his neighbor, we shall be working for peace. + +Some of our finest men of to-day are being trained in modern science +and in modern theology. There is no scorn in their minds for early +science or for early theology. Each served its age, and each taught +its truth. But its truth must be restated in terms of to-day. The old +creeds will always be loved. The old creeds will always hold our +reverence and allegiance. But each age must be at liberty to interpret +these creeds in the terms in which that age best understands truth. +Each age must be at liberty "to restate the doctrines of the past in +accordance with the newness of the age and with the ancient verity of +truth." How feeble my own attempt is in this matter, I quite +understand; I am still a child of the struggle. It has all come in my +lifetime and I have seen and felt not a little of the bitterness of +it. I believe the time is ripe for a definite peace. I believe our +children, if we do not hamper them, will never know the struggle we +have had. In every great institution throughout this broad land men of +earnest mind and noble soul are teaching the truth as God gives it to +them to know the truth. Let us not hesitate to entrust our children to +their hands. To us they may seem to be teachers of discord but they +are not speaking in terms that we understand. They are using the +language of a new age. Underneath their teaching lies the everlasting +truth. Out of their teaching will come everlasting life. Let us trust +God in the world. Let us believe that in this age he is teaching men's +lips and dwelling in men's hearts. Only so can we give to our children +the best their times can give them. If we insist in holding these men +back to our conception we but deny them the privilege of moving with +God's great procession. We make them laggards when they should be in +the front ranks, their faces lighted by a nearer and clearer vision of +Almighty truth. + + + + +INDEX + + A + + Acquired characters not inherited, 52. + + Adaptation and purpose, 89. + + Adaptation for the individual, 87. + + Adaptation for the species, 125. + + Advanced teaching, 291. + + Agassiz and evolution, 19. + + Age of the earth, 156. + + Allantois of chick, 206. + + American Museum of Natural History, 221. + + Anaxagoras and evolution, 9. + + Anaximander and evolution, 8. + + Ancestry of man, 186. + + Andes rising out of Pacific, 32. + + Aquinas, Thomas, and evolution, 12. + + Archaeopteryx, 181. + + Aristotle and evolution, 9. + + Armadillo and glyptodon, 29. + + Artificial flavors, 161. + + Artificial proteids, 161. + + Artificial sugars, 161. + + Ascent of man, 189. + + Asexual reproduction, 194. + + Augustine, Saint, and evolution, 11. + + Australian mammals, 186. + + + B + + Bank swallow's nest, 146. + + Barnacles studies by Darwin, 34. + + Beagle and Darwin's voyage, 25. + + Beauty of human female, 127. + + Biologists accept evolution, 278. + + Bird colors, 131. + + Bird from reptile, 122. + + Bird nests, 145. + + Birds of a region definite, 61. + + Bird song, 135. + + Blowing viper, 107. + + Blue birds and frost, 61. + + Bradbury, Dean, 43. + + Buffon and evolution, 15. + + Bumble bees, 125. + + Butterfly colors, 129. + + Butterfly's mouth, 95. + + + C + + Carboniferous age, 174. + + Carnivorous teeth, 124. + + Caterpillars on leaves, 110. + + Cave man, 188. + + Cells live in water, 166. + + Cenozoic age, 185. + + Cicada killer, 143. + + Circular nest of bird, 147. + + City life in man, 256. + + Clothing of birds, 101. + + Coal plants, 174. + + Cold-blooded animals, 99. + + Color, concealing, Thayer, 115. + + Concealing appearance, 105. + + Cope and Lamarckianism, 244. + + Cope on taste of toad, 118. + + Coral reef formation, 32. + + Country life in man, 256. + + Cretaceous period, 180. + + Cricket song, 134. + + Crinoids, 171. + + Crossing and variation, 53. + + Cuvier criticises Lamarck, 19. + + + D + + Darwin, Charles, + along La Plata, 28. + at Buenos Ayres, 28. + at Keeling Atoll, 31. + at Galapagos, 30. + father of evolution, 21. + in Brazil, 27. + in Patagonia, 29. + in Peru, 30. + on Beagle, 26. + persuaded world of evolution, 21. + studies Lyell's Geology, 26. + studies Malthus, 35. + + Darwin, Erasmus, and evolution, 16. + + Darwin's ancestry, 22. + birth, 23. + burial in Abbey, 43. + death, 43. + education, 23. + narrative of voyage, 33. + patient mind, 45. + purity of mind, 29. + return to England, 33. + short sketches, 39. + study of barnacles, 34. + work double, 233. + + Deer horns, 138. + + Descartes and evolution, 12. + + Descent of man, 189. + + Determinants in nucleus, 238. + + Development of chick, 204. + + Development of pond-snails, 46. + + Devonian age, 173. + + Devonian fish, 173. + + DeVries and mutation, 246. + + Duckmole, 208. + + + E + + Early marriage, 272. + + Earth's age, 155. + + Ecstatic flight, 136. + + Egg-laying mammals, 208. + + Eimer and orthogenesis, 243. + + Elements of Geology, Lyell, 26. + + Emanuel Kant and evolution, 13. + + Embryo of chick, 203. + + Emerson and nature, 48. + + Empedocles and evolution, 8. + + English sparrow (see Sparrow, English). + + Environment in man, 258. + + Eugenic program, 269. + + Evening primrose and mutation, 246. + + Evolution since Darwin, 233. + + + F + + Feeble-mindedness, 264. + + Feet of mammals, 122. + + First living things, 165. + + Fish eggs, 145. + + Fish may freeze, 104. + + Fitz-Roy, Capt., and Beagle, 25. + + Freedom of teaching, 291. + + Fright paralysis, 108. + + Frog's long tadpole stage, 112. + + Frost and bluebirds, 61. + + Fur of seal, 100. + + Future evolution of man, 249. + + + G + + Galapagos Islands and evolution, 30. + + Geological periods, 158. + + Glyptodon and armadillo, 29. + + Goethe and evolution, 20. + + Graphite from plants, 168. + + Grasshopper's mouth, 93. + + Grasshopper song, 133. + + Groundhog and winter, 103. + + Growth of North America, 167. + + + H + + Haeckel advocates evolution, 42. + + Health certificates, 263. + + Henslow and Darwin's education, 24. + + Henslow suggests Darwin for Beagle, 24. + + Heredity and natural selection, 45. + + Heredity in man, 258. + + Homes, few animals have, 98. + + Homes, warm-blooded animals, 101. + + Horn of rhinoceros, 123. + + Horns of deer, 138. + + Horse and early man, 232. + earliest, 223. + neck, 229. + story of, 220. + three-toed, 227. + + Horseshoe crab, 171. + + How mammals developed, 192. + + Huxley at Oxford meeting, 42. + + + I + + Ichneumon fly, 142. + + Image of God, 288. + + Improving the environment, 259. + + Improving the stock, 261. + + Inheritance of acquired characters, 238. + + Insect's biting mouth, 93. + + Interpretation of Genesis, 284. + + Isolation, Jordan, 242. + + Isolation, Romanes, 242. + + Isolation, Wagner, 241. + + + J + + Java skull, 187. + + Jehovah confounding the nations, 289. + + Jordan and isolation, 242. + + Judgment, Michael Angelo, 289. + + Jukes family, 265. + + June-bug, 107. + + + K + + Kallikak family, 265. + + Kant and evolution, 13. + + Katydid's color, 111. + + Katydid's song, 133. + + Keeling Atoll and Darwin, 31. + + King Crab, 171. + + + L + + Lamarck and evolution, 17. + + Lampshells, 172. + + La Place's theory, 151. + + Leibnitz, and evolution, 13. + + Life from other planets, 162. + + Life in the past, 149. + + Life, its nature, 247. + + Linnaean Society and evolution, 40. + + Linnaeus and fixed species, 15. + + Locust's song, 135. + + Lucretius and evolution, 10. + + Lung-fish, 176. + + Lyell's Geology, 26. + + + M + + Male birds brighter, 131. + + Male insects sing, 134. + + Malthus and population, 35. + + Mamma, significance of, 211. + + Mammals, egg-laying, 208. + how developed, 192. + + Man and God's image, 288. + early, and horse, 232. + growing better, 255. + + Man's ancestry, 250. + future evolution, 249. + + Mating and song, 133. + + Mating antics, 136. + + Meaning of Genesis, 284. + + Megatherium and sloth, 29. + + Mesozoic age, 178. + + Michael Angelo, Judgment, 289. + + Migration of birds, 103. + + Missing link, 187. + + Mizpah, 283. + + Modern teachers of biology, 291. + + Mongolian idiot, 265. + + Mosquito's bite, 97. + + Mosquito's mouth, 96. + + Mother-love, 217. + + Multiplication and evolution, 54. + + Mutation and DeVries, 246. + + + N + + Nature of life, 247. + + Nature of milk, 214. + + Natural selection explained, 45. + in brief, 36. + + Nebular hypothesis, 152. + + Neck of horse, 229. + + Neo-Darwinians, 237. + + Nests for warm eggs, 101. + + Number and position of breasts, 215. + + + O + + Odor as protection, 117. + + Opossum playing dead, 107. + + Origin of birds, 181. + feathers, 102. + flight, 122. + hair, 102. + life, 159. + lungs, 177. + milk glands, 212. + placenta, 210. + variations, 50. + + "Origin of Species" published, 41. + + Orthogenesis and Eimer, 243. + + Oxford meeting of British Association, 41. + + + P + + Palaeozoic era, 170. + + Paley's Natural Theology, 87. + + Pangenesis, 236. + + Patagonia and its terraces, 29. + + Phenacodus, 185. + + Physical evolution of man, 254. + + Pithecanthropus, 188. + + Planetesimal theory, 155. + + Playing dead, 107. + + Playing 'possum, 107. + + Polygamy in animals, 137. + + Pond-snail, development of, 46. + + Potato worm, 142. + + Protective coloration, 109. + + Protoplasm, 164. + + Pterodactyl, 180. + + Puff adder, 107. + + Purpose and adaptation, 89. + + Purpose in nature, 88. + + + Q + + Quiet and escape, 105. + + + R + + Raining toads, 113. + + Religion and evolution, 74. + + Reptiles of Mesozoic, 179. + + Reproduction, asexual and sexual, 194. + in fishes, 196. + in frogs, 199. + in reptiles, 202. + + Rhinoceros horn, 123. + + Romanes and isolation, 242. + + Rooster finer than hen, 132. + + + S + + Saint Augustine and evolution, 11. + + Salamanders, 176. + + Sargent's picture, 289. + + Science and the book, 274. + + Science and theology, 280. + + Science, definition, 280. + + Seals and polygamy, 139. + + Sealskin and fur, 100. + + Sedgwick and Darwin, 24. + + Selection and evolution, 56. + + Sexual selection, 126, 128. + + Skunk's odor, 117. + + Sloth and megatherium, 29. + + Song and mating, 133. + + Sparrow, English, adapted to town, 66. + and hawks, 69. + and winter, 73. + eat varied food, 71. + eye-minded, 78. + feed young on insects, 72. + good qualities, 85. + has reached limit, 85. + in Philadelphia, 63. + introduction, 62. + lives near houses, 70. + nests early, 81. + nests often, 82. + once migratory, 80. + quarrels without animosity, 75. + sociable, 74. + spread of, 65. + stays over winter, 79. + successful, 83. + transported in cars, 67. + unafraid of man, 69. + wintering, 73. + + Sparrow, House, 62. + + Sphex wasp, 143. + + Spider cocoons, 139. + + Spider, young, 140. + + Spontaneous generation, 159. + + Stone lilies, 171. + + Story of the horse, 220. + + Struggle against enemies, 104. + for food, 91. + for shelter, 92. + for the individual, 90. + for the species, 91, 125. + + Sunfish and young, 196. + + + T + + Taste of toad, 118. + + Teeth of mammals, 98. + + Temperature of mammals, 99. + + Tertiary era, 185. + + Thayer, concealing color, 115. + + Theology and science, 280. + + Theology, definition, 280. + + Thomas Aquinas and evolution, 12. + + Three-toed horse, 227. + + Toad, bad taste, 118. + color, 112. + enemies, 113. + short tadpole stage, 112. + + Tomato worm, 142. + + Turtles and young, 202. + + Tusks of elephant, 124. + + Tussock worm, 64. + + Two methods of reproduction, 194. + + Types of insect mouth, 93. + + + U + + Understanding the Bible, 281. + + Underwing moth, 130. + + + V + + Variation and natural selection, 49. + by crossing, 53. + + Virchow and man's ancestry, 187. + + Vireo's color, 115. + + + W + + Wagner and isolation, 241. + + Wallace and evolution, 39. + + Warm-blooded animals, 99. + + Weissman and evolution, 235. + + Wilberforce, Bishop, and evolution, 41. + + Wintering of ground hog, 103. + + Wintering of mammals, 103. + + Wintering of squirrels, 103. + + Woodchuck, 103. + + Woodpecker's nest, 146. + + + Y + + Young growing finer, 272. + + + + +APPENDIX + +BIBLIOGRAPHY + + +In connection with each chapter, wherever this is possible, there are +four classes of references. First is named a small and inexpensive but +satisfactory book on the subject. Second, a more comprehensive book, +readily accessible and not unduly expensive. Then a few of the most +satisfactory reference books on the subject independent of cost or +ready availability. Fourth, a list of references to articles in the +eleventh edition of the Encyclopedia Britannica. + + +CHAPTER I. _Evolution before Darwin._ + +1. -- -- -- -- + +2. Biology and Its Makers, Locy. + +3. From the Greeks to Darwin, Osborn. Chapters 1, 2, 3, 19. + +4. Encyclopedia Britannica, 11th edition, article, _Evolution_, +section, _History_. + + +CHAPTER II. _Darwin and Wallace._ + +1. The Coming of Evolution, Judd. + +2. Charles Darwin, Poulton. + +3. Life and Letters of Charles Darwin, by his son, Francis Darwin. 2 +vols. + +My Life, A. R. Wallace. 2 vols. + +4. Encyclopedia Britannica, articles _Darwin_, _Wallace_. + + +CHAPTER III. _The Underlying Idea._ + +1. Evolution, Geddes and Thompson. + +2. The Origin of Species, Charles Darwin. + +3. The Evolution Theory, Weissmann. 2 vols. + +4. Encyclopedia Britannica, articles _Variation_ and _Selection_. + + +CHAPTER IV. _Adaptation for the Individual._ + +1. Colin Clout's Calendar, Grant Allen. + +2. Evolution and Animal Life, Jordan and Kellogg. Chapters 16, 19. + +3. Darwinism, Wallace. + +4. Encyclopedia Britannica, articles _Adaptation_, _Colours of +Animals_, _Hibernation_. + + +CHAPTER V. _Adaptation for the Species._ + +1. Colin Clout's Calendar, Grant Allen. + +2. Evolution and Animal Life, Jordan and Kellogg. + +3. Darwinism, Wallace. + +4. Encyclopedia Britannica, articles, _Metamorphosis_, _Song of +Birds_. + + +CHAPTER VI. _Life in the Past._ + +1. The Story of Our Continent, Shaler. + +2. Elements of Geology, Blackwelder and Barrows. + +3. The Story of Evolution, McCabe. + +4. Encyclopedia Britannica, article, _Geology_ (palaeontological and +physiographical). + + +CHAPTER VII. _How the Mammals Developed._ + +1. -- -- -- -- + +2. Plant and Animal Children, Torelle. + +3. -- -- -- -- + +4. Encyclopedia Britannica, article, _Mammalia_. + + +CHAPTER VIII. _The Story of the Horse._ + +1. The Evolution of the Horse in America, Osborn, in _The Century_, +November, 1904. + +The Evolution of the Horse, Matthew. + +2. The Horse, Flower. + +3. Encyclopedia Britannica, article, _Horse_. + + +CHAPTER IX. _Evolution Since Darwin._ + +1. The Evolution of Living Organisms, Goodrich. + +2. Biology and Its Makers, Locy. Chapters 14, 18. + +3. Darwinism To-day, Kellogg. + +4. Encyclopedia Britannica, articles, _Romanes_, _Weissmann_, +_Mendel_. + + +CHAPTER X. _The Future Evolution of Man._ + +1. The Problem of Race Regeneration, Ellis. + +2. Inquiries into Human Faculty, Galton. + +3. Heredity, Thompson. + +4. Encyclopedia Britannica, articles, _Eugenics_, _Galton_. + + +CHAPTER XI. _Science and the Book._ + +1. -- -- -- -- + +2. The Origin and Permanent Value of the Old Testament, Skater. + +3. The Life and Literature of the Ancient Hebrews, Abbott. + +4. Encyclopedia Britannica, articles, _Genesis_, _Bible_ (Old +Testament Canon). + + +REVIEW QUESTIONS + +_Foreword._ 1. What is the purpose of this book? + +Chapter I. 1. What were some of the theories of the Greek +philosophers, and what shadowing of truth was there in their beliefs? +2. What was Lucretius's idea? 3. What were the explanations of Genesis +given by St. Augustine and by Thomas Aquinas? 4. What were theories of +Descartes, Leibnitz, and Kant? 5. How is the delay of the thought of +evolution accounted for? 6. What were the contributions of Linnaeus, +Buffon, Erasmus, Darwin, Lamarck? 7. What check to progress was made +by Cuvier and Agassiz? 8. What phases of evolution were studied by +Goethe? + +Chapter II. 1. Sketch the life of Charles Darwin. 2. What advantages +did he derive from the "Beagle" expedition? 3. What is the theory of +Natural Selection, and how did Darwin arrive at it? 4. Describe the +Wallace and Wilberforce incidents. 5. What has been the progressive +attitude toward the Darwinian idea? + +Chapter III. 1. Explain Heredity as the conservative force of nature. +2. Explain Variation as the progressive tendency in nature. 3. In what +ratio is the Multiplication of animals? 4. How does the process of +Selection make for the survival of the fittest? 5. What three +possibilities are open to animals under a change of environment? 6. +What is the history of the English Sparrow in this country, and how is +his increase accounted for by his powers of adaptation? + +Chapter IV. 1. Show how the struggle for existence as affecting food, +results in adaptations in the individual. Give illustrations. 2. Do +the same for the results of struggle for shelter. 3. What are some of +the adjustments resulting from the need of protection from foes? + +Chapter V. 1. Discuss coloration. 2. How is sound used as an +attraction? 3. What are some of the other methods of attracting mates? +4. What are some of the specializations produced by polygamy? 5. +Describe some of the protections and provisions for the young. + +Chapter VI. 1. What is La Place's Nebular Hypothesis? 2. What is the +Planetesimal Theory? 3. What bases have been used for calculation of +the age of the earth? 4. Reproduce the Table of Geological Times. 5. +What is the Theory of Spontaneous Generation? 6. What is the theory of +life development from organic dust in space? 7. Discuss protoplasm. 8. +What was the probable growth of the North American continent? 9. What +is the nature of the fossils in the earliest layers of stratified +rock? 10. Describe the life of each of the three periods of the +Palaeozoic era. 11. Do the same for the Mesozoic era. 12. What was the +effect upon life of the development of seasons and of climates? 13. +What physical characteristics of the earth helped in the development +of new animal forms in the Cenozoic era? 14. What has been the ascent +of man? + +Chapter VII. 1. Illustrate the asexual method of reproduction. 2. +Trace the two-parent method of reproduction upward from the simplest +forms. 3. What has been the development of the milk glands? 4. How +does the prolonged care of the young by the mother indicate the higher +development of the animal? + +Chapter VIII. 1. Describe the earliest known ancestor of the horse? 2. +What changes took place in the second stage of development? 3. What is +the form by the middle of the Tertiary period? 4. What was the size of +the late Tertiary horse, and how was the grinding power of the teeth +increased? 5. How was the early Quaternary horse adapted for speed and +for eating? 6. How is the extermination of the horse in North and +South America accounted for, and how was he introduced again? + +Chapter IX. 1. How extensive has the belief in evolution become since +Darwin's day? 2. How does the theory of Natural Selection fail in +accounting for Variation; how did Darwin try to amend his original +theory; and what is Weissmann's belief. 3. What second objection has +been brought against the theory of Natural Selection, and what have +been the contributions of Wagner, Jordan, and Romanes to the +discussion? 4. What is the third objection to Darwinism, and what is +the bearing upon it of the theory of Orthogenesis? 5. What is the +American and French tendency toward the belief that use is the cause +of the persisting of organs? 6. How did DeVries discover the +principle of mutation, and how does it apply to the discussion of +evolution? + +Chapter X. 1. What was the cause of the passing of the civilization of +Athens, of Judea, of Sparta? 2. What promise of uniform development is +evident to-day, and what are some of the hindrances? 3. What has been +the changing emphasis in the evolution of man? 4. How is man the +arbiter of his own destiny? 5. What is the task of the eugenist; how +is he trying to accomplish it, and what are some of the possibilities +suggested. 6. What is the promise for the future? + +Chapter XI. 1. What is the duty of the fair-minded person toward the +essential truths of religion and of science? 2. What two difficulties +lie in the path of reconciliation, and why should each century restate +its truths? 3. What three steps are desirable in studying the Bible? +Illustrate. 4. What is the essential truth of the early chapters of +Genesis, and what its glory? 5. Interpret the meaning of "creation of +man in God's image." 6. What is our duty to ourselves and our +children? + + + + + +End of the Project Gutenberg EBook of The Meaning of Evolution, by +Samuel Christian Schmucker + +*** END OF THIS PROJECT GUTENBERG EBOOK THE MEANING OF EVOLUTION *** + +***** This file should be named 29422.txt or 29422.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/2/9/4/2/29422/ + +Produced by Juliet Sutherland, Chris Logan and the Online +Distributed Proofreading Team at http://www.pgdp.net + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. 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