apply to the other, and, philosophically speaking, there is no other mode of approaching the question. We must deal with life as we find it, and however much science may fail in its demonstration, it is bound at least to make the attempt. In the present state of human knowledge, reason may be unable to grasp all the subtle and multifarious conditions that regulate the development of vitality on our globe; under a deeper and broader insight into nature's operations, the truth may begin to dawn upon us, and all the sooner and clearer the sooner and more earnestly we commence the investigation.

Admitting the philosophy of the methods, we may still be permitted to inquire how far any or all of these hypotheses are adequate to the solution of the problem? In the first place, it is obvious that external conditions operate powerfully in the distribution of plants and animals, and it is also admitted that they modify, in the long-run, the species subjected to their operation; but it seems incredible that they could transform one species into another species, or one order into another order, without the aid of other and more intimate physiological causes. Even combining

the force of external conditions with the use and disuse of organs, and with the impulse of hereditary tendencies in the embryonic or foetal stage of each successive generation, the combination seems inadequate without some other factor to keep the successive development in conformity with the known plan of vitality. Should we add the operation of natural selection, which is admittedly a powerful and everactive agent in the modification of species, still the questions remain-how plants and animals should exist in their present ordinal arrangements, and how their appearance in time should coincide, in the main, with these ordinal arrangements? There are clearly some other factors over and above all those which have yet been brought for

ward, to account for the plan of vital development; some physiological law for the general order of Life analogous to that which governs the growth and development of the individual. The better, then, that we understand the physiology of individual growth and varietal divergence-the fuller our knowledge of the paleontological order and ascent of vitality-the sooner will we be enabled to arrive at some indication of this Law of progressional development. If the teachings of Geology are not a delusion, the fact of vital progression on this globe is as certain as the succession of its stratified formations. Science has already done much to arrange and elucidate the one; may we not hope that under the light of increasing knowledge and more philosophical methods, human reason shall by-and-by attain to a satisfactory explanation of the other? It is admitted that in course of time, and under new conditions, plants and animals do break into new varieties. Variation is thus merely a matter of time and continuance of condition. And if this be admitted, we have only to discover in the respective species those physiological peculiarities which give direction and character to the new variations. Mysterious as the ordainings of life may seem, the problem is manifestly bound up with the operating forces of the universe, and as such is hopefully within the reach of science, as it is certainly within its legitimate domain. All that we know of the growth, reproduction, and decay of vitality are the results of physical causation, which can be investigated and determined; shall we cease to believe that its development in time is similarly produced and as capable of demonstration?

The outcry that has been raised in certain quarters against these hypotheses of vital development is utterly senseless and unworthy. Investigators perceive that certain plans pervade the vegetable and animal kingdoms, and that the whole is inseparably associated in one vital

scheme. They perceive that life is governed in its distribution and existence by the operating forces of the universe; they learn from Geology that it has taken a certain order of ascent in time, from lower to higher forms; and as students of nature, they endeavour to account for its progression by appealing to the forces by which it is manifestly affected. Philosophically there is no other course

left to them. They must deal with life as they deal with the other phenomena of the universe; and human reason is never more religiously occupied than when earnestly striving to comprehend and account for the designs and methods of the Creator. If there has been any irreverence in dealing with this problem, that irreverence must rest with those who would circumscribe the range of reason, and seek, by unworthy clamour, to deter the human intellect from rising to some conception, however faint, of the laws by which the Creator has chosen to develop the phenomena of His marvellous universe. The authors of these hypotheses may be right, or they may be wrong, in their views; they may ascribe too much or too little to certain agencies: but so long as they honestly endeavour to arrive at the truth, their opinions ought to be gratefully received and treated with candour. As students of science, they abide by scientific methods; and unless Life is to be altogether removed from the category of Natural Science, they have no alternative but to treat it in all its bearings— its rise, progress, and inter-relations-as they would deal with any other problem that comes within the scope of their investigations. Higher than mere material phenomena, more subtle in its relations than any physical agency, more marvellous in its growth and reproduction than any other department of nature, its comprehension, no doubt, taxes the severest efforts of the human understanding; but still, as portion of the universe, it partakes of all

its progress, and must be amenable to all its laws. In this view, Life is simply one of the great features of the universe, carried along with it through all its mutations, and governed by the same great law of creational progression.

And this great law of creational progression is alike operative in the material, vital, intellectual, and moral phenomena of the universe. Nothing stands still. That which has been will never occur again; that which appears now will assume a different aspect in the future. All the former distributions of sea and land, with their various surfaces, climates, and productions, have disappeared; and the existing distribution is as incessantly passing into newer forms and aspects. All the phases of life which Geology has revealed differ with each successive formation; higher succeeds lower at each advancing stage; and the present, we may rest assured, will be followed by a similar progressional advancement. Man, too, in all his interrelations, is subject to the same all-pervading law. Physically, the lower variety has preceded the higher, and the highest variety of the present day stands on a lower platform than that which is destined to succeed it. Race after race has risen from barbarism to higher and higher stages of intellectualism and civilisation; and in the moral world clearer and purer views gain, age by age, a wider recognition and more general fulfilment. Nothing stands still; truth alone is eternal; and as the whole world, physical, vital, intellectual, and moral, must partake of this progress, truth itself will illuminate a broader field, and lead to nobler and more godlike activities.*

"In the lapse of ages, hypothetically invoked for the mutation of specific distinctions," says Professor Owen, "I would remark that Man is not likely to preserve his longer than contemporary species theirs. Seeing the greater variety of influences to which he is subject, the present characters of the human kind are likely to be sooner changed than those of lower existing species. And with such change of specific

Such seems to have been and to be the destined order and succession of vitality. As in existing plants and animals we perceive a vast variety of grades from lower to higher forms, so throughout the development of Life in time there has been a coincident ascent from the lower to the higher orders. During the primary periods the lands and waters were peopled only by the lowest forms; but as time rolled on, higher and higher orders gradually made their appearance, each successive rock-system bearing testimony to the introduction of newer and more highly organised existences. Imperfect as the geological record admittedly is, and limited as may be the portions of the earth's crust yet examined, there is such a coincidence in the fossil life of all the surveyed tracts, that we may regard the order of ascent as an established fact, subject only to minor modifications in the details. The differences that have arisen among geologists relate not to the facts of the ascent, but to the mode or modes in which the development has been brought about. As we know more of extinct life and more of the physiology of existing life, these differences will in a great measure disappear, and conflicting hypotheses give way to a uniform and satisfactory theory. In the mean time every earnest endeavour is entitled to our regard, and however startling its views, or how little soever it may seem to clear the way to sounder conclusions, it ought to be gratefully received as a contribution towards the solution of the highest and most interesting problems, perhaps, that the progress of discovery has submitted to the consideration of modern philosophy.

character, especially if it should be in the ascensive direction, there might be associated powers of penetrating the problems of zoology, so far transcending those of our present condition as to be equivalent to a different and higher phase of intellectual action, resulting in what might be termed another species of zoological science."-Preface to Comparative Anatomy and Physiology of Vertebrates.