D'Orbigny, that, irrespectively of general and sudden catastrophes, or any known adequate physical cause, there has been a total depopulation at the close of each geological period or formation, say forty or fifty times, or more, followed by as many independent great acts of creation, at which alone have species been originated, and at each of which a vegetable and an animal kingdom were produced entire and complete, full-fledged, as flourishing, as wide-spread and populous, as varied and mutually adapted from the beginning as ever afterwards, such a view, of course, supersedes all material connection between successive species, and removes even the association and geographical range of species entirely out of the domain of physical causes and of natural science. This is the extreme opposite of Wallace's and Darwin's view, and is quite as hypothetical. The nearly universal opinion, if we rightly gather it, manifestly is, that the replacement of the species of successive formations was not complete and simultaneous, but partial and successive; and that along the course of each epoch some species probably were introduced, and some, doubtless, became extinct. If all since the tertiary belongs to our present epoch, this is certainly true of it: if to two or more epochs, then the hypothesis of a total change is not true of them. Geology makes huge demands upon time; and we regret to find that it has exhausted ours, that what we meant for the briefest and most general sketch of some geological considerations in favor of Darwin's hypothesis has so extended as to leave no room for considering "the great facts of comparative anatomy and zoology" with which Darwin's theory "very well accords," nor for indicating how "it admirably serves for explaining the unity of composition of all organisms, the existence of representative and rudimentary organs, and the natural series which genera and species compose." Suffice it to say that these are the real strongholds of the new system on its theoretical side; that it goes far towards explaining both the physiological and the structural gradations and relations between the two kingdoms, and the arrangement of all their forms in groups subordinate to groups, all within a few great types; that it reads the riddle of abortive organs and of morphological conformity, of which no other theory has ever offered a scientific explanation, and supplies a ground for harmonizing the two fundamental ideas which naturalists and philosophers conceive to have ruled the organic world, though they could not reconcile them, namely: Adaptation to Purpose and the Conditions of Existence, and Unity of Type. To reconcile these two undeniable principles is a capital problem in the philosophy of natural history; and the hypothesis which consistently does so thereby secures a great advantage. We all know that the arm and hand of a monkey, the foreleg and foot of a dog and of a horse, the wing of a bat, and the fin of a porpoise are fundamentally identical; that the long neck of the giraffe has the same and no more bones than the short one of the elephant; that the eggs of Surinam frogs hatch into tadpoles with as good tails for swimming as any of their kindred, although as tadpoles they never enter the water; that the Guinea-pig is furnished with incisor teeth which it never uses, as it sheds them before birth; that embryos of mammals and birds have branchial slits and arteries running in loops, in imitation or reminiscence of the arrangement which is permanent in fishes; and that thousands of animals and plants have rudimentary organs which, at least in numerous cases, are wholly useless to their possessors, etc., etc. Upon a derivative theory this morphological conformity is explained by community of descent; and it has not been explained in any other way. Naturalists are constantly speaking of "related species," of the "affinity" of a genus or other group, and of "family resemblance," vaguely conscious that these terms of kinship are something more than mere metaphors, but unaware of the grounds of their aptness. Mr. Dar win assures them that they have been talking derivative doctrine all their lives without knowing it. If it is difficult and in some cases practically impossible to fix the limits of species, it is still more so to fix those of genera; and those of tribes and families are still less susceptible of exact natural circumscription. Intermediate forms occur, connecting one group with another in a manner sadly perplexing to systematists, except to those who have ceased to expect absolute limitations in Nature. All this blending could hardly fail to suggest a former material connection among allied forms, such as that which an hypothesis of derivation demands. Here it would not be amiss to consider the general principle of gradation throughout organic Nature, -a principle which answers in a general way to the law of continuity in the inorganic world, or rather is so analogous to it that both may fairly be expressed by the Leibnitzian axiom, Natura non agit saltatim. As an axiom or philosophical principle, used to test modal laws or hypotheses, this in strictness belongs only to physics. In the investigation of Nature at large, at least in the organic world, nobody would undertake to apply this principle as a test of the validity of any theory or supposed law. But naturalists of enlarged views will not fail to infer the principle from the phenomena they investigate, to perceive that the rule holds, under due qualifications and altered forms, throughout the realm of Nature; although we do not suppose that Nature in the organic world makes no distinct steps, but only short and serial steps, not infinitely fine gradations, but no long leaps, or few of them. To glance at a few illustrations out of many that present themselves. It would be thought that the distinction between the two organic kingdoms was broad and absolute. Plants and animals belong to two very different categories, fulfil opposite offices, and, as to the mass of them, are so unlike that the difficulty of the ordinary observer would be to find points of comparison. Without entering into details, which would fill an article, we may safely say that the difficulty with the naturalist is all the other way,-that all these broad differences vanish one by one as we approach the lower confines of the two kingdoms, and that no absolute distinction whatever is now known between them. It is quite possible that the same organism may be both vegetable and animal, or may be first the one and then the other. If some organisms may be said to be at first vegetables and then animals, others, like the spores and other reproductive bodies of many of the lower Algæ, may equally claim to have first a characteristically animal, and then an unequivocally vegetable existence. Nor is the gradation purely restricted to these simple organisms. It appears in general functions, as in that of reproduction, which is reducible to the same formula in both kingdoms, while it exhibits close approximations in the lower forms; also in a common or similar ground of sensibility in the lowest forms of both, a common faculty of effecting movements tending to a determinate end, traces of which pervade the vegetable kingdom,while on the other hand, this indefinable principle, this vegetable animula vagula, blandula, graduates into the higher sensitiveness of the lower class of animals. Nor need we hesitate to recognize the fine gradations from simple sensitiveness and volition to the higher instinctive and other psychical manifestations of the higher brute animals. The gradation is undoubted, however we may explain it. Again, propagation is of one mode in the higher animals, of two in all plants; but vegetative propagation, by budding or offshoots, extends through the lower grades of animals. In both kingdoms there may be separation of the offshoots, or indifference in this respect, or continued and organic union with the parent stock; and this either with essential independence of the offshoots, or with a subordination of these to a common whole, or finally with such subordination and amalgamation, along with specialization of function, that the same parts, which in other cases can be regarded only as progeny, in these become only members of an individual. -- This leads to the question of individuality, a subject quite too large and too recondite for present discussion. The conclusion of the whole matter, however, is, that individuality - that very ground of being as distinguished from thing — is not attained in Nature at one leap. If anywhere truly exemplified in plants, it is only in the lowest and simplest, where the being is a structural unit, a single cell, memberless and organless, though organic,the same thing as those cells of which all the more complex plants are built up, and with which every plant and (structurally) every animal began its development. In the ascending gradation of the vegetable kingdom individuality is, so to say, striven after, but never attained; in the lower animals it is striven after with greater, though incomplete success; it is realized only in animals of so high a rank that vegetative multiplication or offshoots are out of the question, where all parts are strictly members and nothing else, and all subordinated to a common nervous centre, fully realized, perhaps, only in a conscious person. So, also, the broad distinction between reproduction by seeds or ova and propagation by buds, though perfect in some of the lowest forms of life, becomes evanescent in others; and even the most absolute law we know in the physiology of genuine reproduction, that of sexual cooperation, has its exceptions in both kingdoms in parthenogenesis, to which in the vegetable kingdom a most curious series of gradations leads. In plants, likewise, a long and most finely graduated series of transitions leads from bisexual to unisexual blossoms; and so in various other respects. Everywhere we may perceive that Nature secures her ends, and makes her distinctions on the whole manifest and real, but everywhere without abrupt breaks. We need not wonder, therefore, that gradations between species and varieties should occur; the more so, since genera, tribes, and other groups into which the naturalist collocates species are far from being always absolutely limited in Nature, though they are necessarily represented to be so in systems. From the necessity of the case, the classifications of the naturalist abruptly define where Nature more or less blends. Our systems are nothing, if not definite. They are intended to express differences, and perhaps some of the coarser gradations. But this evinces, not their perfection, but their imperfection. Even the best of them are to the system of Nature what consecutive patches of the seven colors are to the rainbow. Now the principle of gradation throughout organic Nature may, of course, be interpreted upon other assumptions than those of Darwin's hypothesis, - certainly upon quite other than those of materialistic philosophy, with which we ourselves have no sympathy. Still we conceive it not only possible, but probable, that this gradation, as it has its natural ground, may yet have its scientific explanation. In any case, there is no need to deny that the general facts correspond well with an hypothesis like Darwin's, which is built upon fine gradations. We have contemplated quite long enough the general presumptions in favor of an hypothesis of the derivation of species. We cannot forget, however, while for the moment we overlook, the formidable difficulties which all hypotheses of this class have to encounter, and the serious implications which they seem to involve. We feel, moreover, that Darwin's particular hypothesis is exposed to some special objections. It requires no small strength of nerve steadily to conceive not only of the variation, but of the formation of the organs of an animal through cumulative variation and natural selection. Think of such an organ as the eye, that most perfect of optical instruments, as so produced in the lower animals and perfected in the higher! A friend of ours, who accepts the new doctrine, confesses that for a long while a cold chill came over him whenever he thought of the eye. He has at length got over that stage of the complaint, and is now in the fever of belief, perchance to be succeeded by the sweating stage, during which sundry peccant humors may be eliminated from the system. For ourselves, we dread the chill, and have some misgiving about the consequences of the reaction. We find ourselves in the "singular position" acknowledged by Pictet, - that is, confronted with a theory which, although it can really explain much, seems inadequate to the heavy task it so boldly assumes, but which, nevertheless, appears better fitted than any other that has been broached to explain, if it be possible to explain, somewhat of the manner in which organized beings may have arisen and succeeded each other. In this dilemma we might take advantage of Mr. Darwin's candid admission, that he by no means expects to convince old and experienced people, whose minds are stocked with a multitude of facts all viewed during a long course of years from the old point of view. This is nearly our case. So, owning no call to a larger faith than is expected of us, but not prepared to pronounce the whole hypothesis untenable, under such construction as we should put upon it, we naturally sought to attain a settled conviction through a perusal of several proffered refutations of the theory. At least, this course seemed to offer the readiest way of bringing to a head the various objections to which the theory is exposed. On several accounts some of these opposed reviews specially invite examination. We propose, accordingly, to conclude our task with an article upon "Darwin and his Reviewers." REVIEWS AND LITERARY NOTICES. Modern Painters. By J. RUSKIN. Vol. V. Smith, Elder, & Co. London. THE Completion of a work of the importance of the "Modern Painters," which has occupied in its production the thought and a large portion of the labor of fourteen years, is an event of more interest than it often falls to the lot of a book to excite; but when, as in this case, the result shows the development of an individual taste and critical ability entirely without peer in the history of art-letters, the value of the whole work is immensely enhanced by the time which its publication covers. The first volume of "Modern Painters " was, as everybody will remember, one of the sensation-books of the time, and fell upon the public opinion of the day like a thunderbolt from the clear sky. Denying, and in many instances overthrowing, the received canons of criticism, and defying all the accepted authorities in it, the author excited the liveliest astonishment and the bitterest hostility of the professional critics in general, and at once divided the world of art, so far as his influence reached, into two parts: the one embracing most of the reverent and conservative minds, and by far the larger; the other, most of the enthusiastic, the radical, and earnest; but this, small in numbers at first, was increased, and still increases, by the force of those qualities of enthusiasm and earnestness, until now, in England, it embraces nearly all of the true and living art of our time. But that volume, professedly treating art with reference to its superficial attributes and for a special purpose, the redemption of a great and revered artist from unjust disparagement and undeserved neglect, touched in scarcely the least degree the vital questions of taste or art-production. It had no considerations of sentiment or discussion of principles to offer: it dealt with facts, and touched the simple truths of Nature with an enthusiastic fire and lucidness which were proof positive of the knowledge and feeling of the author; and the public, either conversant with those facts or capable of being satisfied of them without much thought, abandoned itself to the fascination of his eloquence and acquiesced in his teachings, or arrayed itself in utter hostility to him and his new ideas. The second volume was more abstruse and deeper in feeling, and comparatively few of Mr. Ruskin's followers through the first cared to get entangled in the metaphysical mazes of the second, and it is generally neglected, although containing some of the deepest and most satisfactory studies on the fundamental principles of art and taste which have ever been printed. The third and fourth volumes, coming up again nearer the surface, made an application of the principles investigated to the material for art which Nature furnishes; and here again the author found in part his audience diminished among those who had at first been carried away by his enthusiasm or silenced and convinced by his unhesitating dogmatism. A partial reaction took place, owing not only to the change in the tone of the "Modern Painters," but to the springing up of a new school of painting, the consequence, mainly and legitimately, of the teachings of the work, the pre-Raphaelite, which, at once attacked virulently and immeasurably by the old school of critics, and defended as earnestly by Mr. Ruskin, became the subject of the war which was still waged between him and them. Turner in the meanwhile had passed away and was admitted to apotheosis, the malignant critics of yesterday becoming the ignorant adulators of to-day his position was conceded, but the hostility to Ruskin was sustained with unabated bitterness on the new field. He was demolished anew, and proved, many useless times over and over, an ignorant pretender; the public in the meanwhile, even his opponents, taking up in turn his protégés, as he pointed them out to their notice. The effect of his criticisms in enhancing the value of the works they approved would be incredible, if one did not know how glad an English public is to be led. As a single instance, - a drawing which was sold from one of the water-color exhibitions at fifty guineas, sold again, after Ruskin's notice, at two hundred and fifty; and in the lists of pictures sold or to be sold at auction, one sees constantly, "Noticed by Mr. Ruskin," "Approved by Mr. Ruskin," appended to the title. The third volume, being devoted to the correction of the ideas of Style and the Ideal, to Finish, and a review of the Past Landscape-Painting, recurs to Turner in its closing chapter, "On his Teachers"; the fourth was given to Mountain Beauty, following the parallel of the first, which treated of the Truth of Mountains, and bearing as its burden of moral the expression of that Ideal by Turner; and the fifth now comes to conclude the investigations on the Ideal by chapters: first, on "Leaf Beauty," an exceedingly interesting investigation of the development of the forms of trees and plants as concerned with the laws of beauty; second, " Cloud Beauty"; and then of the "Ideas of Relation," in which the author comes finally to the demonstration of the right of Turner to his position amongst the thinking and poetic painters. From the first division, "Leaf Beauty," we must make one extract. The author has been speaking of the influence of the Pine on Swiss character. "But the point which I desire the reader to note is, that the character of the scene which, if any, appears to have been impressive to the inhabitant is not that which we ourselves feel when we enter the district. It was not from their lakes, nor their cliffs, nor their glaciers, though these were all peculiarly their possession, that the three venerable cantons or states received their name. They were not called the States of the Rock, nor the States of the Lake, but the States of the Forest. And the one of the three which contains the most touching record of the spiritual power of Swiss religion, in the name of the convent of the 'Hill of Angels,' has for its own none but the sweet, childish name of 'Under the Woods.' "And, indeed, you may pass under them, if, leaving the most sacred spot in Swiss history, the Meadow of the Three Fountains, you bid the boatman row southward a little way by the Bay of Uri. Steepest there, on its western side, the walls of its rocks ascend to heaven. Far in the blue of evening, like a great cathedral-pavement, lies the lake in its darkness; and you may hear the whisper of innumerable falling waters return from the hollows of the cliff like the voices of a multitude praying under their breath. From time to time, the beat of a wave, slow lifted, where the rocks lean over the black depth, dies heavily as the last note of a requiem. Opposite, |