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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.

A

MONG 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 expressionSurvival 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

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