If the elephants could be reared in captivity there is little reason to doubt that with a few centuries of selection they might be made to vary in many important ways. It is evident that the form and mental quality of these creatures is as plastic as those features in the other domesticated animals have been proved to be. Moreover, the group, though it is now represented by but two recognized species, was in comparatively recent times quite rich in varieties, a fact which raises the presumption that the existing kinds are open to modification by the selective process. As the elephant is not mature until it is near thirty years old, probably not reproducing until about that age, there is little inducement for any person to undertake the process of breeding them in the selective way; if the task is ever done it will have to be accomplished by government action or by that of a society which is pledged to such tasks. If the effort to bring the elephants into a more permanent relation with man is not made and the race is allowed to perish, we may be sure that in the time to come people will gravely censure us for any such neglect of the opportunities which this world affords as would be involved in the loss of this noble brute. It is clearly our duty to see that all such resources are preserved for the inquirers of the future.
Among the other tropical mammals which, because they have not as yet proved of economic value, are on account of their size and their attractiveness to sportsmen in danger of extinction, we may note the various species of rhinoceros, the giraffe, and the several African forms which are akin to the horse. None of these forms have been turned to use, none of them appear likely to be adopted by man for the service they can do; but they are, in common with all the host which cannot be mentioned here, of great interest to the naturalists of our time. Their importance in the inquiries which are hereafter to be made by our ever expanding science of life cannot be estimated. It certainly will not be possible to overreckon it in this very practical age. This plea for the sparing of the mammalian species in no case needs to be made so strongly, and in no other instance is so well entitled to a hearing, as when it is raised for the life of the monkeys. These interesting animals because of their collateral kinship with man afford precious evidence as to the stages of intellectual development which is likely to be of exceeding value to students in that field of inquiry. There is unfortunately little chance that any of the monkeys will ever prove useful; their habits are such that they are generally troublesome neighbors; moreover, their weakness makes it easy to exterminate them. The result is that some species have probably already been destroyed, and others are in conditions where during the next century they are likely to vanish. In the animate realm it is hard to choose the forms which are to be the most important for the naturalists of the time to come, but it is certain that these students will deplore the loss of the simian life and charge us sorely if we neglect due effort for its preservation.
Although the matter before us concerns the domestication of animals, it may be well to devote a little attention to the question of the wild plants which need protection or which promise to afford unwon values. It may be said that plants in general are much less likely than animals to be disturbed by the process of bringing a country under the conditions of civilization. With rare exceptions the individuals of each species are so numerous that, like the insects, they escape by their numbers the risk of the extinction of their kinds. Moreover, the ease with which nearly all the kinds can be brought under cultivation, and the fact that they present no self-will to be dominated, makes the task of dealing with them, in a protective way, infinitely easier than in the case of animals. So far as we know, there has not been an instance in which a continental species of plant has been exterminated by man, while there are a number of the larger animals which have been swept away apparently by human agency, and there are many more which are on the verge of extinction. Therefore, so far as the plant world is concerned, we may for the present at least trust the species to their own powers to maintain them against the rude assaults of civilization. If here and there one is overrun by the wheels of our economic engines, something of value to the student is lost, but the loss does not include the element of mind which is hereafter to be the subject of so much study.
The foregoing considerations make it evident that the problem of domestication shades into the question as to the preservation of the life which is now on the earth, and this with a view to the advantage which the arts, the sciences, or general culture may obtain from the preservation of the useful, the instructive, and the beautiful things in the realm of nature from the swift destruction which our rude subjugation of the earth threatens to inflict. To deal with this problem in an adequate manner we must ask ourselves what limits are to be set to the displacement of the ancient order which is now going on. We see that wherever civilization enters, and even where its first influences are felt, the olden societies of nature are disturbed or broken up. All the nobler members of these associations, the greater mammals, many of the larger birds, and a host of the lesser forms, are expelled or destroyed. In the condition of organic life when the supremely predatory creature man rose to domination, the species were grouped in those vast organizations which were of old termed faunæ and floræ, but which are now better known as biological fields or provinces. In each of these hosts the several species were, as regards their external life, so balanced with their neighbors that the assemblage from the point of view of these relations might well be compared with the polities or states of man's construction. Such an organic society represents the result of a series of trials and balances which began to be made in the immeasurably remote past and have been continued through the geologic ages, each age adding something to the accord. The plants give and take from the animals; the insects are equated with the birds, and each species in every group has set up an accord with its rivals. From time to time the host has by the changes of sea and land been compelled to migrate, moving this way and that to find its fit station. In these movements species are rapidly extinguished, much as the weaker soldiers of an army perish in forced marches. Into their places new forms hasten to take their place, so that every position of advantage is filled. At a less rapid rate, but perpetually, even without the change of abode, which it is often by climatic changes compelled to make, the organic host is slowly changing in character; old kinds give way in the endless contest to new varieties which have managed to establish a better relation to the environment. Still the legions press on towards the great accomplishment of a higher and nobler life.
No one, however well he may conceive the nature and history of the organic hosts of the earth, can hope to convey to the general reader an adequate sense of their majesty or the wonderful part they have played in the history of the life which has culminated in mankind. The largest words are freighted with too little meaning, and even the metaphors drawn from human associations fail to convey a sufficient picture of these enduring organizations which have enabled living beings to meet the difficulties of their long contest with this rude world, and to win the advance they have gained. The reader will have to tax his imagination to picture, it may be, a quarter of a million species dwelling in the same field, each united with the other in the method of exchange in such a way that the withdrawal of any one form is likely in some measure to change the estate of every other. In some cases this removal of one species means the loss of the life of many and perhaps the better opportunity of other neighbors; again, the influence on remoter members of the society may be so slight as to escape detection. Yet it is doubtful if the slightest change in the population of a biologic province can be brought about without some effect upon all the members of the society. It is a vast, sensitive thing, fit to be compared with the living body where every cell lives in accord with every other of the frame.
So long as the organic hosts were in the prehuman stage the maintenance of the accord was easily and naturally attained. Species arose and perished, each in turn effecting a simple reconciliation with the others, grasping only so much room and food as was necessary for its proper support. But with the coming of man, the species which by its swiftly progressive desires has become a host in itself, a disturbing element was introduced into the old order. Man as a primitive savage falls into the natural system without greatly disturbing it; but man as a soil-tiller, in so far as he carries out his subjugative work, utterly wrecks the ancient establishments of life. To attain his object he has to banish from the soil nearly all the plants which originally belonged upon it, and in their place, with or without intention, he introduces species from other organic provinces. With the change in plant-life necessarily goes a like, or even a greater, alteration in the native animals. They are driven into the wilderness or, it may be, extirpated. The reader who would obtain an idea of these changes will do well to study the invasions of weeds or of those noxious insects which in the economy of a civilized country may be likened to weeds. These pests are in nearly all cases invaders which owe their successes to the fact that our treatment of the regions they have entered has opened vacancies in the once closed ranks of the indigenous host, into which the foreigners are free to enter. In the fresh field they are not likely to find enemies which by long training are especially fitted to cope with them, and so they run riot and contest with man the gains he has won from the ancient possessors of the land.
Of all the large questions which the consideration of the future of man's work on this planet opens to us, there is none which now appears to be more serious or, in its consequences, more far-reaching than this concerning the treatment which he is to give to the old natural order of sea and land. The very first condition of civilization is an utter spoiling of that order, so far as the land areas are concerned, in the fields of the richest and highest life. It is clearly impossible to avoid this destruction over all the surface which we win to culture. Spare as we may, the subversion of the ancient balances and adjustments must be complete before the earth is ready for our tillage and other modes of use. This overturning is a part of the destiny of man. It is a characteristic of the new dispensation which came with his progressive desires. Yet the rational quality which has led to the mastery of man may be trusted to bring him to a point where he will endeavor to minimize the ill effects of his actions on the life which has been placed in his hands.
In considering the ways in which we can mitigate the evils of our rule over organic nature, we at once see that our aim should be to preserve all the varieties of living creatures from destruction, provided they are not distinctly harmful to man, and this with the intention of keeping for our successors in the inheritance all that can in any way afford a foundation for further experiments in domestication, materials for learned inquiries, or pleasure in contemplation. To attain this object we cannot trust to the share of this life which can be brought into zoölogical and botanical gardens, however extensive and well managed. The only way is to make certain reservations in various parts of the world, each containing an area and a variety of conditions great enough to afford a safe lodgment for a true sample of the life of an organic province. Owing to the fact that these provinces are never sharply bounded, it would naturally be impossible to select reservations which would in a complete manner represent all the conditions of the biologic societies; but if properly distributed the outlying animals and plants could in most if not all cases be introduced into one or other of these protected fields, so that there would be little reason to fear that any important part of the existing life would be lost.
Owing to the wise forethought of our American people, a practical foundation of the system of national reservations has been instituted in our so-called national parks. Although these reservations were established to preserve to the public certain natural beauties in the way of scenery or vegetation, or to secure the regimen of streams, they will, if properly guarded against depredations, effect the end which we have in view. Owing to their large area and somewhat varied positions, these parks provide a safe refuge for a great part of the life which belongs in the Cordilleran district of the United States. If the method should be extended to the whole country, we should have the peculiar satisfaction of having been the first state to institute the system of preservation which is here suggested.
To complete a system of reservations designed to perpetuate the aboriginal life of this country would require the institution of about a dozen other similar natural shelters. It would not be necessary to have these on as large a scale as that of the Yellowstone. In most cases areas of from ten to twenty thousand acres in extent would, if well guarded, suffice to give refuge to the animals and plants of the field in which it lay. The selection of these refuges would demand much consideration. In general, it may be said that they need to include at least two on the Atlantic coast, which might also be fitted for the use of marine birds as breeding places, one on the northern part of the coast of Maine, and another in southern Florida. The latter might serve as well for the protection of the turtles which resort to that shore to lay their eggs. Similar coast parks should be established on the shores of the Pacific. Yet other closed areas would be needed in the interior, the evidently desirable fields lying in the region about the headwaters of the Mississippi, in the Adirondacks, in the mountains of North Carolina, in the lower part of the Mississippi delta, in Arizona, and at least two points in Alaska; one of these should afford a place of refuge for the persecuted fur seals and another for the musk-ox.