continuation, through numerous geological, goographical, and more recently historical changes, of anterior vegetations, the actual distribution of plants is seen to be a consequence of preceding conditions; and geologi cal considerations, and these alone, may be expected to explain all the facts-many of them so curious and extraordinary-of the actual geographical distribution of the species. In the present essay, not only the distribution but the origin of congeneric species is rogarded as something derivative; whether derived by slow and very gradual changes in the course of ages, according to Darwin, or by a sudden, inexplicablo change of their tertiary ancestors, as conceived by Heer, De Candolle hazards no opinion. It may, how ever, be inferred that he looks upon "natural selection" as a real, but insuflicient cause; while somo eurions remarks upon the number of monstrosities annually produced, and the possibility of their enduring, may be regarded as favorable to Heer's view.

As an index to the progress of opinion in the direction referred to, it will be interesting to comparo Sir Charles Lyell's well-known chapters of twenty or thirty years ago, in which tho permanence of species was ably maintained, with his treatment of the samo subject in a work just issued in England, which, however, has not yet reached us."

A belief of the derivation of species may be maintained along with a conviction of great persistenco of specific characters. This is the idea of the excellent Swiss vegetable paleontologist, Heer, who imagines a sudden change of specific typo at certain periods, and perhaps is that of Pictet. Falconer adheres to

comowhat similar views in his elaborato paper on elephants, living and fossil, in the Natural History Review for January last. Noting that "there is clear evidence of the true mammoth having existed in America long after the period of the northern drift, when the surface of the country had settled down into its present form, and also in Europe so late as to have been a contemporary of the Irish elk, and on the other hand that it existed in England so far back as before the deposition of the bowlder clay; also that four well-defined species of fossil elephant are known to have existed in Europe; that "a vast number of the remains of three of these species have been exhumed over a large area in Europe; and, even in the geological sense, an enormous interval of time has clapsed

between the formation of the most ancient and the most recent of these deposits, quite suflicient to test the persistence of specific characters in an elephant," he presents the question, "Do, then, the successivo elephants occurring in theso strata show any signs of a passage from the older form into the newer?"

To which the reply is: "If there is one fact which is impressed on the conviction of the observer with more force than any other, it is the persistenco and uniformity of the characters of the molar teeth in the earliest known mammoth and his most modern successor.. Assuming the observation to be correct, what strong proof does it not afford of the persistence and constancy, throughout vast intervals of time, of the distinctive characters of those organs which are most concerned in the existence and habits of the species? If we cast a glance back on the long vista

of physical changes which our planet has undergone since the Neozoic epoch, we can nowhere detect signs of a revolution more sudden and pronounced, or moro important in its results, than the intercalation and sudden disappearance of the glacial period. Yet the 'dicyclotherian' mammoth lived before it, and passed through the ordeal of all the hard extremities it involved, bearing his organs of locomotion and digestion all but unchanged. Taking the group of four European fossil species above enumerated, do they show any signs in the successive deposits of a transition from the one form into the other? Here again tho result of my observation, in so far as it has extended over the European area, is, that the specific characters of the molars are constant in each, within a moderato range of variation, and that we nowhere meet with intermediate forms." . ... Dr. Falconer continues (page S0):

"The inferences which I draw from theso facts are not opposed to one of the leading propositions of Darwin's theory. With him, I have no faith in the opinion that the mammoth and other extinct elephants made their appearanco suddenly, after the typo in which their fossil remains are presented to us, The most rational view, seems to be, that they are in some shapo the modified descendants of earlier progenitors. But if tho asserted facts be correct, they seem clearly to indicato that tho older elephants of Europe, such as E. meridionalis and E. antiquus, were not the stocks from which the later species, E. primigenius and E. Africanus sprung, and that we must look elsewhere for their origin. The nearest aflinity, and that a very close one, of the European E. meridionalis is with the Mioceno E. planifrons of India; and of E. primigenius, with tho oxisting India species.

"Another reflection is equally strong in my mind-that tho

moans which have been adduced to explain the origin of the species by 'natural selection,' or a process of variation from external influences, are inadequate to account for the phenomona. The law of phyllotaxis, which governs the evolution of leaves around the axis of a plant, is as nearly constant in its manifestation as any of the physical laws connected with the material world. Each instance, however different from another, can be shown to be a term of some series of continued fractions. When this is coupled with the geometrical law gov. erning the evolution of form, so manifest in some departments of the animal kingdom, c. g., the spiral shells of the Mollusca, it is difficult to believe that there is not, in Nature, a deeperscated and innato principle, to the operation of which natural selection is merely an adjunct. The whole range of the Mainmalin, fossil and recent, cannot furnish a species which has had a wider geographical distribution, and passed through a longer term of time, and through moro extremo changes of climatul conditions, than the mammoth. If species are so unstable, and so susceptible of mutation through such influences, why does that extinct form stand out so signally a monument of stability? By his admirable researches and earnest writings, Darwin has, beyond all his contemporaries, given an impulse to the philo sophical investigation of the most backward and obscure branch of the biological sciences of his day; he has laid the foundations of a great edifice; but he need not be surprised if, in the progress of erection, the superstructure is altered by his successors, liko the Duomo of Milan from the Roman to a different style of architecture."

Entertaining ourselves the opinion that something more than natural selection is requisite to account for the orderly production and succession of species, we offer two incidental remarks upon the above extract.

1. We find in it-in the phrase "natural selection, or a process of variation from external influences "an example of the very common confusion of two distinct things, viz., variation and natural

selection. The former has never yet been shown to have its cause in "external influences," nor to occur at random. As we have elsewhero insisted, if not inexplicable, it has never been explained; all wo can yet say is, that plants and animals are prone to vary, and that some conditions favor variation., Perhaps in this Dr. Falconer may yet find what ho seeks: for "it is difficult to believe that there is not in [its] nature a deeper-seated and innate principle, to the opera tion of which natural selection is merely an adjunct.” The latter, which is the ensemble of the external influences, including the competition of the individuals themselves, picks out certain variations as they arise, but in no proper sense can be said to originate them.

2. Although we are not quite sure how Dr. Falconer intends to apply the law of phyllotaxis to illustrate his idea, we fancy that a pertinent illustration may be drawn from it, in this way. There aro two species of phyllotaxis, perfectly distinct, and, wo suppose, not mathematically reducible the one to the other, viz.: (1.) That of alternate leaves, with its varieties; and (2.) That of verticillate leaves, of which op posite leaves present the simplest case. That, although generally constant, a change from one variety of alter nate phyllotaxis to another should occur on the samo axis, or on successive axes, is not surprising, the dif ferent sorts being terms of a regular series—although, indeed, we have not the least idea as to how the chango from the one to the other comes to pass. But it is interesting, and in this connection perhaps instructive, to remark that, while some dicotyledonous plants hold to the verticillate, i. c., opposite-leaved phyllotaxis