Chapter XV: Part 15

Now that it has been seen that there has been a gradual progression and development of animal types all through the ages up to the era of man, the question naturally occurs whether or not the changes are still going on which will result in a higher development. Man coexisted in Western Europe with several remarkable mammals in the later portion of the Post-Pliocene Period. While we do not know the causes which led to the extinction of the mammoth, woolly rhinoceros, cave-lion and others, yet we do know that scarcely any mammalian species have become extinct during the historical period. The species with which man coexisted are such that presumably required a very different climate to that now prevailing in Western Europe. Some of the deposits in which man’s remains have been found in association with the bones of extinct mammals incontestably show that great changes in the physiography and surface-configuration of the country had taken place since the period of their accumulation, the human implements themselves bearing evidence of an exceedingly barbarous condition of the human species. Post-Pliocene, or Palæolithic man, was clearly unacquainted with the use of the metals. Not only was this the case, but the workmanship of these ancient races was much inferior to that of the later tribes, who were also ignorant of the metals, and who also used nothing but weapons and tools of stone, bone, etc., in war, chase and domestic affairs. When first man spread over the earth, he had no domestic animals, perhaps not even the dog, and had no knowledge of agriculture. His weapons were of the rudest character, and his houses scarcely worthy of the name. No doubt can exist that his food, habits and entire manner of living have varied as he has passed from country to country, for he must then have been far more subject to the influence of external circumstances, and in all probability more susceptible of change. Moreover, his form, which is now stereotyped by long ages of repetition, may reasonably be presumed to have been more plastic than is now the case. As long as man led a mere animal existence, he would be subject to the same laws, and would vary in the same manner as the rest of his fellow-creatures. But when at last he had acquired the capacity of clothing himself, and of making weapons or tools, he has taken away from nature, in a great measure, that power of changing the external form and structure which she exercises over all other animals. From the time, then, when his social and sympathetic feelings came into active operation, and his intellectual and moral faculties became fairly developed, man’s physical form and structure would not be so much influenced by natural laws, and, therefore, as an animal, he would become almost stationary, his environment ceasing to have upon him that powerful modifying effect which it exercises over other parts of the organic world. But from the moment that his body became less subject to the changes of the surrounding universe, his mind would become acted upon by the influences which the body had escaped. Every slight variation in his mental and moral nature, which would consequently be brought about, and which would enable him better to guard against adverse circumstances, and league together for mutual comfort and protection, would be preserved and accumulated. The better and higher specimens of our race would therefore increase and diffuse themselves, while the lower and more brutal would succumb and successively die out, and that rapid advancement of mental organization would occur, which has raised the very lowest races of men, whose mentality was scarcely superior to the animal, to that high position which it has attained in the Germanic races. It would be too bold an assertion to say that man’s body has become stationary. Slow and gradual changes still take place, although his mere bodily structure long ago became of less importance to him than that subtle energy, which is termed mind. No one can doubt that _this_ gave his naked and unprotected body clothing against the varying inclemencies of the seasons and enabled him to compete with the deer in swiftness and the wild bull in strength by giving him weapons wherewith to capture or subdue them both. Though less capable than most other animals of subsisting on the herbs and the fruits of unaided nature, it was this wonderful faculty that taught him to govern and direct nature to his own benefit, and compel her to produce food for him when and where he pleased. From the moment, then, when the first skin was used as a covering, the first rude spear fashioned to aid in the chase, and the first seed sown or shoot planted, a grand revolution was effected in nature, a revolution which had had no parallel in all the previous cycles of the world’s history, for a being had arisen who was no longer necessarily subject to a changing universe, a being who was in some degree superior to nature, inasmuch as he knew how to control and regulate her action, and could maintain himself in unison with her, not by a change brought about in the body, but by a growth and advance in mind. Therein are shadowed forth the true grandeur and dignity of man. Not only has he achieved for himself a great victory in this rising by the power of mind superior to nature in a sense, but he has also gained a directing influence over other existences, in that he has been able to grasp from nature some of that power which, before his appearance, she universally exercised. From all that man has accomplished in the past, it is easy to anticipate the time when only cultivated plants and domestic animals will be produced by the earth, and when the ocean, which, for countless cycles of ages ruled supreme over the globe, will be the only domain in which that power can be exercised.

That man has improved under civilization there can be no question. Statistics show that, since the introduction of civilization, the population of the earth in general has increased. No one can fail to observe that under its influence the means of subsistence have increased even more rapidly than the population. Far from suffering for lack of food, the most densely peopled countries are those in which it is, not only absolutely but even relatively most abundant. A thousand men live to-day in plenty upon an area of ground that would scarcely afford a scanty and precarious subsistence to a single savage. There is no denying the fact that happiness is increased by civilization. To talk of the free and noble savage is folly. The true savage is neither free nor noble. He is a slave to his own wants, his own passions. Imperfectly protected as he is from the weather, he suffers at night from the cold and by day from the heat of the sun. Ignorant of agriculture, living by the chase, and improvident in success, hunger ever stares him in the face, and often drives him to the dreadful alternative of cannibalism or death. The life of all beasts in their wild state is certainly an exceedingly anxious one. So it is with the savage. He is always suspicious, always in danger, always on the watch. He can depend on no one, and no one can depend upon him, for he expects nothing from his neighbor, and does unto others as he believes that they would do unto him. His life is one prolonged scene of selfishness and fear. Even in his religion, if he has any, he creates for himself a new source of terror, and peoples the world with invisible enemies. More wretched is the position of the female savage than that of her master, for she not only shares his sufferings, but has also to bear his ill-humor and ill-usage, being little better than his dog, little dearer than his horse. Few of them, it is believed, are so fortunate as to die a natural death, being despatched ere they become old and emaciated, that so much good food shall not be lost. Indeed, so little importance is attached to women, either before or after death, that it may be doubted whether the man does not esteem his dog, when alive, quite as much as he does his woman, and think of both quite as often and as lovingly after he has made a meal of them. Not content, moreover, with the pleasures incident to their mode of life, savages appear to take a melancholy delight in self-inflicted sufferings. They not only tattoo their bodies, but practise the most extraordinary methods of disfigurement and self-torture, some amputating the little finger, while others drill immense holes in the under-lip, or pierce the cartilage of the nose. These and many other curious practices, none the less painful because they are voluntary, are in vogue among savage people. Turning now to the bright side of the question, we cannot but conclude that the pleasures of civilized man are greater than those of the savage. While man will never be able to improve the organization of the eye or the ear, yet, on the other hand, the invention of the telescope and the microscope is equivalent in its results to an immense improvement of the eyes, thus opening up to us new worlds, fresh sources of interest and happiness, while the training of the ear will enable us to invent new musical instruments and compose new melodies. The savage, like a child, sees and hears only that which is brought directly before him, but the civilized man questions nature, and by the various processes of chemistry, electricity and magnetism, and a thousand ingenious contrivances, forces nature to reveal herself, thereby discovering hidden uses and unsuspected beauties, quite as marvellously as though he were endowed with some entirely new organ of sense. Through the discovery of printing, we are brought into communion with the greatest minds, and thus the thoughts of a Shakespeare or a Tennyson, or the discoveries of a Newton or a Darwin, become the common property of mankind. Already the results of this all-important, though simple, process have vastly improved our mental faculties, and day by day, as books become cheaper, schools are established and education more general, a greater and greater effect will be produced.

Nor are all these new sources of happiness accompanied by any new liability to suffering. On the contrary, while our pleasures are increased, our pains are lessened. In a thousand ways we can avoid or diminish evils which to our ancestors were great and unavoidable. No one can estimate the misery which, for instance, the simple discovery of chloroform has spared the human race. The capacity for pain, so far as it can serve as a warning, remains all the same, but the necessity for endurance has been greatly diminished. With increased knowledge of the laws of health, and attention thereto, disease will become less and less frequent, and those tendencies to disease which we have inherited from our ancestors will gradually die out, and, if fresh seeds are not sown, the race will one day enjoy the inestimable advantages of a more vigorous and healthy existence. Thus, then, with the increasing influence of science we may confidently look forward to a great improvement in the condition of man. But it may be alleged that our present sufferings and sorrows arise chiefly from sin, and that any moral improvement must come from religion and not from science. This separation of the two mighty agents of improvement, the great misfortune of humanity, has done more than anything else to retard the progress of civilization. But even if we admit for the nonce that science will not render us more virtuous, it must certainly make us more innocent, for in fact the most of our criminal population are mere savages, persons who can rarely read and write, and whose crimes are but injudicious and desperate attempts to live a savage life in the midst, and at the expense, of a civilized community. Men do wrong either from ignorance or in the hope, unexpressed perhaps even to themselves, that they may enjoy the pleasure and yet avoid the penalty of sin. All that they have to do they think, when they have committed sin, is to repent. The religious teaching of the day has much to do with this misapprehension. Repentance is too frequently regarded as a substitute for punishment. Sin it is thought is followed either by the one or the other. So far, therefore, as this world is concerned, this is not the case; repentance may enable a man to avoid sin in future, but has no effect on the consequences of the past. The laws of nature are not only just and salutary, but they are also inexorable. While all men admit that “the wages of sin is death,” yet they seem to think that this is a general rule to which there may be many exceptions, that some sins may possibly tend to happiness. That suffering is the inevitable consequence of sin, as surely as an effect follows a cause, is the stern yet salutary teaching of science. And certainly if this lesson were thoroughly impressed upon our minds, that punishment and not happiness is the consequence of sin, then temptation, which is the very root of crime, would be cut away, and mankind must therefore necessarily become more innocent. May we not go still further and say that science will also render us more virtuous? He who studies philosophy can only obtain a just idea of the great things for which Providence has fitted his understanding. Such a study not only makes our lives more agreeable, but it also makes them better, and every motive of interest and duty should constrain a rational being to direct his mind towards pursuits which all experience has shown to be the sure path of virtue and happiness.

Man is in reality but on the threshold of civilization. Far from showing any indication of having reached the end, the tendency to improvement seems laterally to have proceeded with augmented impetus and accelerated rapidity. There is no reason to suppose that it must now cease. Man has not attained the limits of intellectual development, nor exhausted the infinite capabilities of nature. There are many things not yet dreamt of in our philosophy which science must reveal, many discoveries yet to be made which will confer upon the human race advantages which as yet, perhaps, we are not in a condition to grasp and appreciate. We seem, when we compare our present knowledge with the great ocean of truth that lies all undiscovered before us, like little children playing on the sea-shore, and picking up a smoother pebble and prettier shell than any they had met with before. Thus, it is obvious, that our most sanguine hopes for the future are justified by the entire experience of the past. It is surely unreasonable to presume that a process which has been going on for so many thousand years should have now suddenly ceased; and he must indeed be blind who thinks that our civilization is unsusceptible of improvement, or that we ourselves are in the highest state possible for man to attain. Theory, as well as experience, forces the same conclusion upon us. That principle of Natural Selection, which in animals affects the body and seems to have little influence on the mind, in man affects the mind and has little influence on the body. In the former it leads mainly to the preservation of life, and in the latter to the improvement of the mind, and consequently to the increase of happiness. It ensures, in the words of Spencer, “a constant progress towards a higher skill, intelligence, and self-regulation--a better coördination of actions--a more complete life.” Nearly all the evils under which we suffer, it will be conceded, may be attributed either to ignorance or sin. That ignorance will be diminished by the progress of science is, of course, self-evident; and that the same will be the case with sin, seems little less so. Thus, then, do both science and theory point to the same conclusion. That which poets hardly dared to hope for, the future happiness of our race, science boldly predicts. Even in our own time we trust to see some wonderful improvement. But the unselfish mind, however, will find its highest gratification in the belief that, whatever may be the case with ourselves, our descendants will understand many things which are mysterious to us now, will better appreciate the beautiful world in which we live, avoid much of the suffering to which we are subject, enjoy many blessings of which we are not yet worthy, and escape many of those temptations which we deplore but cannot wholly resist.

We have thus seen that all life has been progressive. There has been through the ages a steadily growing upward tendency to higher life. But the changes have mainly been in the line of physical form and structure. And such, too, had been the case with man, until his social, intellectual and moral faculties had begun to assert themselves, when his body ceased in a great measure to be acted upon by physical laws, and development began to manifest itself in a higher type of mental organization. From the low, simple, childlike mind of palæolithic man has come that wonderful intellect which now characterizes the Germanic races, and which is destined to make itself felt in its contact with all the earth. Those peoples that are able to embrace the new civilization brought to their doors, so to speak, will survive, while the others, unable to adapt themselves thereto, like the Tasmanian, will succumb in the struggle with a superior being and go to the wall. Animals and plants will be brought into new relations and new conditions, and such as can meet the new requirements will, as certain species have done before, endure. They will, in other words, have partaken of an enlightened civilization. Thus things will go on until all life, vegetal and animal, will be brought under the controlling and elevating influence of man, and then will be inaugurated on earth that condition when the lion and the kid shall lie down together, and a little child shall be found in their midst. Nothing harmful will anywhere exist. Heaven will then have been brought down to earth, and peace and harmony will universally prevail. Then will have come the complete triumph of mind over body. All growth and development of the reformed and regenerated earth-man will be in the direction of mind, and his accomplishments will he share with the inferior subjects of his peaceful and happy domain. Progression, however, will not cease, but will go on steadily advancing as the years increase. And if there is a life beyond the earth-life, then the intellect or mind, or soul if you please, shall, in some form or other, exist therein, and reach up into higher and yet higher growth and development.

SURVIVAL OF THE FITTEST.

Among organic beings in a state of nature there is some individual variability. This is an admission about which there can be no dispute. But the mere existence of individual variability and of a few well-marked varieties, though necessary as the foundation for the work, assists us but little in understanding how species originate in nature. Those exquisite adaptations of one part of the organization to another part, and to the conditions of life, and of one organic being to another being, which we know to exist, seem as mysteries. We see them in the humblest parasite that clings to the hairs of a quadruped or the feathers of a bird, in the structure of the beetle that dives through the water, and in the plumed seed that is wafted by the gentlest breeze. In short, we see beautiful adaptations everywhere and in every part of the organic world. And yet, how few have paused while admiring these beautiful and wonderful co-adaptations to ask themselves the question: How have these been perfected?

If the existence of any well-marked varieties be admitted, how is it that these varieties, which may be denominated incipient species, become ultimately converted into good and distinct species, which in the generality of cases obviously differ from each in a greater degree than do the varieties of the same species? How do these groups of species, which constitute what are authoritatively called genera, and which differ from each other more than do the species of the same genus, arise? All these results, as will presently be seen, follow from the Struggle for Existence. Owing to this struggle, all variations, no matter how slight they may be, or from what cause soever they may proceed, will, if they be in any degree profitable to the individuals of a species in their infinitely complex relations to other organic beings and their physical conditions of life, unavoidably conduce to the preservation of such individuals, and generally be inherited by the offspring. The offspring, too, will thus have a better chance of surviving, for, of the many individuals of a species that are periodically born, but a very small number can survive. That principle, by which each slight variation, if useful to the individual, is preserved, has been termed Natural Selection by Darwin, in order to distinguish it from the selection which is exercised by man over the plants and animals which he has brought under subjection for his own wants. But the expression--Survival of the Fittest--so frequently used by Spencer, is more accurate, and sometimes equally convenient. Man can certainly produce great results by this power, and can adapt, through the accumulation of slight but useful variations given to him by the hand of nature, organic beings to his own uses. But Natural Selection, as is well known, is a power incessantly ready for action, and is as infinitely superior to man’s feeble efforts as the works of nature are to those of art.

All organic beings are exposed to severe competition. Nothing is easier than to admit in words the truth of the universal struggle for life, or more difficult than constantly to bear this conclusion, which has been reached through the investigations and researches of De Candolle, Lyell, Herbert, Darwin and others, in mind. Unless, however, it be thoroughly ingrained in the mind, the whole economy of nature, with every fact on distribution, rarity, abundance, extinction and variation, will be but dimly perceived or quite misunderstood. We behold the face of nature radiant with gladness, and food everywhere in excessive abundance, but we do not see that the birds which are happily singing round us mostly live on insects or seeds, and are thus constantly destroying life, or we fail to remember how largely these songsters, or their eggs, or their nestlings, are destroyed by birds and beasts of prey. Yes, we do not always bear in mind that, though food may now be superabundant, it is not so at all seasons of each recurring year. The term, Struggle for Existence, must be used in a large and metaphorical sense. It must be construed to include the dependence of one being on another, and also not only the life of the individual but also its success in leaving offspring. Two carnivores, in a time of scarcity of food, may be truly said to struggle with each other for maintenance of life. But a plant on the edge of a desert is said to struggle for life against the drought, though, properly speaking, it is dependent for its existence upon the moisture. A plant, however, that annually produces many thousand seeds of which on an average only one comes to maturity, may in a much truer sense be said to struggle with the plants of the same and other kinds which already invest the ground. While the mistletoe is dependent on the apple and some other trees, yet it cannot be said, unless in a far-fetched sense, to struggle with these trees, for, if too many of these parasites are found upon the same tree, it will certainly languish and die. Several seedling mistletoes, however, growing close together upon the same branch, may more truly be said to struggle with each other.

From the high rate at which all organic beings tend to increase, there must inevitably follow a Struggle for Existence. Every being which, during its natural lifetime, produces several eggs or seeds, must necessarily suffer destruction during some part of that period, and during some season or occasional year, otherwise, on the principle of Geometrical Increase, its numbers would become so inordinately excessive that no country would be able to support its product. Therefore, as more individuals are produced than can possibly survive, there must be in every case a Struggle for Existence, either one individual struggling with another of the same kind, or with individuals of distinct kinds or species, or with the conditions of the environment. This is the doctrine of Malthus applied with manifold force to the entire vegetable and animal kingdoms. Although some species may be now increasing at a very high rate in numbers, yet all cannot do so, for the earth would not be able to contain them. Slow-breeding man has doubled in twenty-five years, and should he go on at this rate for a few thousand years, there would literally not be standing room for his progeny. It has been calculated that, if an annual plant produced only two seeds, and their seedlings next year produced two, and the same rate of increase was kept up for twenty years, there would be a million of plants as the result. Even the elephant, which is reckoned the slowest breeder of all known animals, would after a period of from seven hundred and forty to seven hundred and fifty years leave nearly nineteen million elephants as descendants from the first pair.

Much better evidence than mere theoretical calculations are not wanting on this subject. Instances are recorded of the astonishingly rapid increase of various animals in a state of nature, when conditions have been favorable to them, during two or three succeeding seasons. More striking, however, is the evidence from domestic animals that have run wild in several parts of the world. Were not the statements of the rate of increase of cattle and horses in South America, and latterly in Australia, where millions now abound, well authenticated, they would have been incredible. Cases could be mentioned of introduced plants that have become quite common throughout entire islands in a period of less than twelve years. Several of these plants, the cardoon and a rare thistle, which were introduced from Europe, clothe square leagues of the surface of the wide plains of the La Plata almost to the exclusion of all other plants; and there are plants which now range in India, from Cape Comorin to the Himalaya, which have been imported from America since its discovery. In all such cases, and endless instances could be adduced, no intelligent person supposes that their fertility has been increased in any sensible degree by change of habitat, the obvious explanation being that the conditions of environment have been very favorable, and that there has consequently been less destruction of old and young, and that nearly all the latter have been enabled to breed. The extraordinarily rapid increase and wide diffusion of naturalized productions in new homes, a result which never fails to evoke surprise, is only to be explained on the principle of the Geometrical Ratio of Increase. As in nature almost every plant produces seed, and there are very few animals that do not annually pair, therefore we can confidently assert that all plants and animals are tending to increase in a geometrical ratio; that all would most rapidly stock every station in which they could in any way exist, and that the tendency to increase must be checked by destruction at some period of life. Among our larger domestic animals we see no great destruction falling on them. We forget that thousands are annually slaughtered for food, and that in a natural state an equal number would have to be disposed of in some way or other. Between organisms which annually produce seeds or eggs by the thousands, and those which produce extremely few, the only difference is that the slow breeders would require a few more years to people, under favorable conditions, a whole district, let it be ever so large. But a couple of eggs are laid by the condor, while the ostrich lays a score. Yet in the same country the condor may be the more abundant of the two. The Fulmer petrel lays but a single egg, yet it is believed to be the most numerous bird in the world. A large number of eggs is of some importance to those species which depend upon a rapidly-fluctuating quantity of food, for it permits them to increase rapidly in number; but the real importance of a large number of eggs or seeds is to make up for the great destruction that goes on at some period of life, and this period in the vast majority of cases is an early one. If an animal can in any way protect its own eggs or young, a small number may be produced, and the average stock be kept up; but if many eggs or young are destroyed, then many must be produced or the species will become extinct. Therefore, the average number of any animal or plant depends, though only indirectly, upon the number of its eggs or seeds. We should never forget, in taking a survey of nature, that every single organic being around us may be said to be striving to the utmost to augment its members; that each lives by a struggle at some period of its existence, and that heavy destruction falls either on the young or old during each generation or at recurrent intervals. Let any check be lightened, or the destruction be mitigated ever so little, and the number of the species will almost instantaneously increase to any extent.

But of the nature of the checks to increase we know little, although this subject has been very ably treated by writers of eminence. Eggs or very young animals seem generally to suffer the most, but this is not invariably the case. While there is a vast destruction of the seeds of plants, but it is the seedlings which are believed to suffer the greatest, from germinating in ground already thickly stocked with other plants, and from being destroyed in large numbers by various enemies. The amount of food for each species of course determines the extreme limit to which each can increase, but very often it is not the obtaining of food, but the serving as prey to other animals which fixes the average number of a species. Thus there seems to be little doubt that the stock of partridges, grouse and hares on any large estate depends mainly on the destruction of vermin. Were not a single head of game shot during the next twenty years in England, says Darwin in substance, and no vermin were at the same time destroyed, there would in all probability be less game than at present exists, although hundreds of thousands of game animals are now annually killed for the market. In some cases, on the other hand, as in the case of the elephant, none are destroyed by beasts of prey, for even the tiger in India, bold and venturesome as he is known to be, rarely dares to attack a young elephant protected by its mother. Climate, also, plays an important part in determining the average number of a species, and periodical seasons of extreme cold or drought are seemingly the most effective checks of all. The action of climate appears at first sight to be altogether independent of the Struggle for Existence; but in so far as it chiefly acts in the reduction of food, it brings on the most severe struggle between the individuals, whether of the same or different species, which subsist on the same kind of fare. Even when climate, extreme cold for example, acts directly, it will be the least vigorous animals, or those which have been the poorest fed through the advancing winter, that will suffer the greatest. This will be most readily seen from what we shall now relate. When we travel from south to north, or from a damp region to a dry, we invariably see some species getting rarer and rarer by degrees, and finally disappearing. Change of climate being conspicuous, we are inclined to ascribe the entire effect to its direct action, but this is a false interpretation of the phenomenon, for we fail to remember that each species, even where it most prevails, is constantly suffering enormous destruction at some period of its existence, from enemies or competitors for the same station and food; and if these enemies or competitors be the least favored by any slight change of climate, they will necessarily increase in numbers, while the other species, each area being already stocked with inhabitants, will correspondingly decrease. And when we travel southward and see a species decreasing in numbers, we may feel reasonably sure that the cause lies quite as much in other species being favored as in this being hurt. So it is when we travel northward, though in a less degree. When we go northward, or when we ascend a mountain, we far oftener meet with stunted forms, due to the directly injurious action of climate, than we do when we go southward or descend a mountain. When, however, we reach the Arctic regions, or explore snow-capped summits, or absolute deserts, we perceive the struggle for life to be almost exclusively with the elements.

That climate operates mainly, but indirectly, in favoring other species, may be clearly seen in the prodigious numbers of garden plants that can thoroughly well endure our climate, but which can never become naturalized, inasmuch as they cannot compete with native vegetation nor resist destruction by native animals.

When a species, owing to highly favorable conditions, increases inordinately in numbers in a small tract of country, epidemics, especially in game animals, often occur, and here we have a limiting check independent of the Struggle for Existence. But some of these so-called epidemics appear to be due to parasitic worms, which have from some cause, possibly in part through ease of diffusion among the crowded animals, been disproportionately favored, and here comes in a sort of struggle between the parasite and its more illustrious prey.

But, on the other hand, as is frequently the case, a large stock of individuals of the same species, relatively to the number of its enemies, is absolutely essential to its preservation. We thus see how it is possible to raise with ease a plentiful supply of corn in our fields, because the seeds are greatly in excess of the number of birds which feed thereon. Nor can the birds, though blessed with a superabundance of food at this one season, increase in number in proportion to the supply of seed, as their numbers are checked during the winter. Any one, however, who has made the experiment, knows how troublesome it is to get seed from a few wheat or other such plants sown broad-cast in a garden. Some singular facts in nature, such as that of very rare plants being sometimes extremely abundant in the few spots where they do occur, and that of some social plants being social, or abounding in individuals, even on the extreme confines of their range, are readily explainable by this view of the necessity of a large stock of the same species for its preservation, for in such cases we may believe that a plant could only exist where the conditions of its life were so favorable that many could exist together and thus save the species from extinction.

Complex and varied are the checks and relations between organic beings which have to struggle together in the same country. In the case of every species, many different checks, some very complicated and unintelligible to man at present, acting at different periods of life, and during different seasons or years, come into play, some one check or some few being generally the most powerful, but all concurring in determining the average number or even the existence of the species. Widely-different checks sometimes act on the same species in different districts. Looking at the plants and bushes that clothe an entangled bank, we are tempted to ascribe their proportional numbers and kinds to what we call chance. But this is a very false view to take of the matter. Chance has no part in such things. They follow in obedience to laws of which we know comparatively little. When an American forest is cut down a very different vegetation springs up. Ancient Indian ruins have been observed in the southern parts of the United States, which must in former times have been cleared of trees, but which now display the same beautiful diversity and proportion of kinds as are now found in the surrounding virgin forest. What a struggle must have gone on during long centuries between the several kinds of trees, each annually scattering its seeds by the thousand, and what a war between insect and insect, and between insects, snails and other animals with birds and beasts of prey, all striving to increase, all feeding on each other, or on the trees, their seeds and their seedlings, or on the other plants which once clothed the soil, and thus checked the growth of the trees! It is easier to account for the fall of an apple from a tree, or the descent of a stone to the earth when hurled into the air, than to account for the action and reaction of the innumerable plants and animals that have determined in the course of untold centuries the proportional numbers and kinds of trees that are now found growing on these old Indian ruins. But the struggle will almost invariably be the severest between individuals of the same species, for they frequent the same districts, require the same food and are exposed to the same dangers. In the case of varieties of the same species, the struggle will generally be almost equally severe. If several varieties of wheat be sown together, and the mixed seed be re-sown, some of the varieties which best suit the soil or climate, or are naturally the most fertile, will beat the others and so yield more seed, and will consequently in a few years supplant the others. Such extremely-close varieties as the variously-colored sweet-peas must be separately harvested each year, and the seed mixed in due proportion, or the weaker kinds will steadily decrease in number and disappear. So, again, with the varieties of sheep. Certain mountain-varieties will starve out other mountain-varieties, so that they cannot be kept together. Similar results have followed from keeping together different varieties of the medicinal leech. In view of all that has been said, it is questionable whether the varieties of any of our domestic plants and animals have so exactly the same vigor, constitution and habits that the original proportions of a mixed stock could be kept up for a half-dozen generations if they were permitted to struggle together like beings in a state of nature, if the seed or young were not annually assorted.

Species of the same genus having usually, though not invariably, much similarity in habits and constitution, and always in structure, the struggle will be more severe between species of the same genus, where they come into competition with each other, than between species of distinct genera. One species of swallow has caused in certain parts of the United States the decrease of another species, just as the missel-thrush in parts of Scotland has caused the decrease of the song-thrush. The small Asiatic cockroach has everywhere in Russia driven before it its great congener, and the imported European hive-bee is rapidly exterminating in Australia the small, stingless bee, indigenous to the country. Hundreds of such cases might be cited, but we forbear. We can clearly see why the competition should be most severe between allied forms, which fill nearly the same place in the economy of nature; but it is perhaps not possible to individualize a case and say with preciseness why such species has been victorious over another in the battle of life. That the structure of every organic being is related, in the most essential yet often hidden manner to that of all the other organisms with which it comes into competition for food or residence, or from which it has to escape, or on which it preys, is a corollary of the highest importance deducible from the foregoing remarks. Very obvious is this in the structure of the teeth and talons of the tiger, and in that of the legs and claws of the parasite which clings to the hair on the tiger’s body. But in the beautifully-plumed seed of the dandelion and the flattened and fringed legs of the water-beetle the relation seems at first restricted to the elements of air and water, yet the advantage of plumed seeds undoubtedly stands in the most intimate relation to the land, being already densely clothed with other plants, so that the seeds may be widely diffused and fall on unoccupied ground, while in the water-beetle, the structure of its legs, so admirably adapted for diving, allows it to compete with other aquatic insects, to hunt for its own prey and to escape destruction by other predaceous animals. All organic beings, it will thus be seen, are not only striving to increase in numbers, but are called upon some time in their lives to struggle for existence or to suffer serious if not utter destruction. When we reflect on this struggle, we can console ourselves with the full belief that this war of nature is not incessant, that no fear is felt, that death is generally sudden, and that the vigorous, healthy and happy survive and multiply.

Seeing what a potent influence the principle of Selection has in the hands of man, in regard to variation, can it be applied in nature? We can see that it can act most effectually. But in our domestic productions the variability is not directly produced by man, for he can neither originate varieties nor prevent their occurrence. All he can do is to preserve and accumulate such as do occur. Unintentionally he exposes organic beings to new and changing conditions of life, for under domestication, plant and animal organizations become in some degree plastic, and variability ensues. Similar changes, however, do occur in nature. When it is borne in mind how infinitely complex and close-fitting are the mutual relations of all organic beings to each other, and to their environment, and consequently what infinitely-varied diversities of structure may be of advantage to each being under altered conditions, can it then be thought improbable, seeing that variations useful to man have undoubtedly occurred, that other variations useful in some way to each being in the great and complex battle of life should sometimes occur in the course of tens of thousands of generations? If such do occur, can we doubt, when it is remembered that many more individuals are born than can possibly survive, that individuals possessing any advantage, no matter how slight, over their fellows would have the best chance of surviving and of procreating their kind? Any variation, on the other hand, we may feel sure if in the least degree injurious would be rigidly destroyed. This preservation of useful and favorable variations, and the destruction of those that are injurious, is called Natural Selection, or the Survival of the Fittest. Variations neither advantageous nor deleterious would not be affected by Natural Selection, and would be left either a fluctuating element, as seen in certain polymorphic species, or would alternately become fixed, owing to the nature both of the organism and its conditions.

We shall best understand the probable cause of Natural Selection by taking a country undergoing some physical change, as of climate for example. The proportional number of its inhabitants would almost immediately undergo a change, and some of its species might become extinct. From the complex and very intimate manner in which the inhabitants of each country are bound together, we may conclude that any change in the numerical proportion of some of its inhabitants, independently of the change of climate itself, would seriously affect the others. Were the country open on its borders, new forms would certainly immigrate, and this, too, would often seriously disturb the relations of some of its former inhabitants. In the case, however, of an island, or a country hemmed in by barriers, into which new and better-adapted forms could not readily enter, we would then meet with places in the economy of nature which would assuredly be better filled up, if some of the original occupants were in some manner modified, for had the area been open to immigration, these same places would have been seized by intruders. Thus, slight modifications, which any way favored the individuals of a species, would by better adapting them to changed conditions tend to become preserved, and Natural Selection would there have free scope for the work of improvement. Changes in the conditions of life cause or excite a tendency to vary. In the foregoing case the conditions are supposed to have changed, and this would manifestly be favorable, by giving a better chance of profitable variations occurring, to Natural Selection, for unless such do occur, Natural Selection can do nothing. As man, by adding up in any given direction individual differences, can certainly produce a great result with his domestic animals and plants, so could Natural Selection, but far more easily from having an incomparably longer time for its action. No great physical change, as of climate, nor any unusual degree of isolation to check immigration, is actually necessary, it would seem, to produce new and unoccupied places for Natural Selection to fill up by modifying and improving some of the varying inhabitants, for as all the inhabitants of a country are struggling together with nicely-balanced forces, extremely-slight modifications in the structure or habits of one species would often give it an advantage over others; and still further modifications, so long as the species continued under the same conditions of life and profited by similar means of subsistence and defence, would often still further augment the advantage. No country can be mentioned whose native inhabitants are now so perfectly adapted to each other and to their environment that none could be better adapted and improved, for in all countries the natives have been so far conquered by naturalized productions as to have allowed them to take firm possession of the land. And as foreigners have thus in every country beaten some of the natives, it may be safely concluded that the latter might have been modified with profit so as to have better resisted the intruders.

A man by his methodical and unconscious means of selection can produce and has produced great results. What may not Natural Selection effect? Man can only operate on external and visible characters, but nature cares nothing for appearances, except in so far as they are beneficial to any being. She can act on every internal organ, on every shade of constitutional difference and, in fine, on the entire machinery of life. Man selects exclusively for his own advantage, but nature solely for that of the being she tends, and under her judicious selection the slightest difference of structure or constitution may well turn the nicely-balanced scale in the Struggle for Existence, and thus be preserved. As fleeting as are the wishes and efforts of man, and as short as is his earthly career, so poor, therefore, must be the results which he accomplishes when compared with those accumulated by nature during whole geological periods. Is it a wonder, then, that her productions should be far _truer_ in character than man’s, and that they should be infinitely better adapted to the most complex conditions of life and should bear the stamp of far higher workmanship? Metaphorically speaking, Natural Selection may be said to be daily and hourly scrutinizing, throughout the world, the slightest variations, rejecting the bad, preserving and adding up the good, and silently and insensibly working, whenever and wherever opportunities occur, at the betterment of each organic being in relation to its organic and inorganic conditions of life. So slow is her work that we see nothing of the changes in progress, and only when the hand of time has marked the lapse of ages do we perceive that changes have been produced; but then so imperfect is our view into long-past geological periods, that we see only that the forms of life are now different from what they formerly were. That any great amount of modification in any point should be effected, a variety once formed must again, perhaps after a long interval of time, present individual differences of the same favorable character, and these must again be preserved, and so onward step by step. As individual differences of all kinds perpetually recur, this can hardly be considered as an unwarrantable assumption. Judged by the extent the hypothesis accords with and explains the general phenomena of nature, notwithstanding the ordinary belief that the amount of possible variation is a strictly-limited quantity, we are justified, it seems to us, in assuming that all this has actually taken place. But in looking at many small points of difference between species, which in our ignorance seem quite unimportant, we must not lose sight of the facts that climate, food and modes of life may have produced some direct effect, and also of the truth that, owing to the Law of Correlation, when one part varies, and the variations are accumulated through the Survival of the Fittest, other modifications often of the most unlooked-for nature will ensue.

As under domestication these variations are known to appear at a particular period of life, and tend to reappear in the offspring at the same period, so, in a state of nature, it is reasonable to infer that Natural Selection will be enabled to act on and modify organic beings at any age, by the accumulation of variations useful at that age, and by their inheritance at a corresponding age. Thus, if it be profitable to a plant to have its seeds more and more widely disseminated by the wind, there can be no greater difficulty in conceiving this to be effected through Natural Selection than in conceiving the increasing and improving of the down in the pods on his cotton-trees by a wise selection upon the part of a cotton-planter. Natural Selection may modify and adapt the larva of an insect to a score of contingencies, wholly different from those which affect the mature insect, and these modifications through Correlation may work changes in the structure of the adult. On the other hand, modifications of the adult may affect the structure of the larva, but in all such cases Natural Selection will insure that these changes shall not be injurious, for, if they were so, the extinction of the species would be the inevitable result. Thousands of instances might be given to show the influence which Natural Selection, or Sexual Selection, which is only a less vigorous phase of the former, has had all through the ages in the adaptation of life to the places in nature which it was intended to occupy in pursuance of the plan formulated by the Great Originator and Designer of the Universe.