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throughout, a larger number-through the operation of some deep-seated and innate principle, which wo cannot fathom-change abruptly into the other species at the second or third node, and change back again in the flower, or else effect a synthesis of the two species in a manner which is puzzling to understand. Iero is a change from one fixed law to another, as unaecountable, if not as great, as from one specific form to another.

An elaborate paper on the vegetation of the Ter tiary period in the southeast of France, by Count Gaston de Saporta, published in the Annales des Sciences Naturelles in 1862, vol. xvi., pp. 309-344-which we. have not space to analyze-is worthy of attention from the general inquirer, on account of its analysis of the Tertiary flora into its separate types, Cretaceous, Austral, Tropical, and Borcal, each of which has its separato and different history-and for the announcement that "the hiatus, which, in the idea of most geologists, intervened between the close of the Cretaceous and the beginning of the Tertiary, appears to have had no existence, so far as concerns the vegetation; that in general it was not by means of a total overthrow, followed by a complete new emission of species, that the flora has been renewed at each successive period; and that while the plants of Southern Europe inherited from the Cretaceous period more or less rapidly dis appeared, as also the austral forms, and later the trop ical types (except the laurel, the myrtle, and the Chamaerops humilis), the boreal types, coming later, survived all the others, and now compose, either in Europe, or in the north of Asia, or in North America,

tho basis of the actual arborescent vegetation. Expo cially "a very considerable number of forms nearly identical with tertiary formis now exist in America, where they have found, more easily than in our [Eu ropean] soil-less vast and less extended southwardrefuge from ulterior revolutions." The extinction of species is attributed to two kinds of causes; the ono material or physical, whether slow or rapid; the other inherent in the nature of organic beings, incessant, but slow, in a manner latent, but somehow assigning to the species, as to the individuals, a limited period of existence, and, in some equally mysterious but wholly natural way, connected with the development of organic types: "By type meaning a collection of vegetable forms constructed upon the same plan of organization, of which they reproduce the essential lineaments with certain secondary modifications, and which appear to run back to a common point of doparture."

In this community of types, no less than in tho community of certain existing species, Saporta recognizes a prolonged material union between North Amer ica and Europe in former times. Most naturalists and geologists reason in the same way-some more cautiously than others-yet perhaps most of them seem not to perceive how far such inferences imply the doctrine of the common origin of related species.

For obvious reasons such doctrines are likely to find more favor with botanists than with zoologists. But with both the advance in this direction is seen to have been rapid and great; yet to us not unexpected. We note, also, an evident disposition, notwithstanding

some endeavors to the contrary, to allow derivative hypotheses to stand or fall upon their own merits-to have indeed upon philosophical grounds certain prosumptions in their favor-and to be, perhaps, quite as capable of being turned to good account as to bad account in natural theology.'

Among the leading naturalists, indeed, such views -taken in the widest sense-have one and, so far as we are now aware, only one thoroughgoing and thoroughly consistent opponent, viz., Mr. Agassiz.

Most naturalists take into their very conception of a species, explicitly or by implication, the notion of a material connection resulting from the descent of the individuals composing it from a common stock, of local origin. Agassiz wholly eliminates community of descent from his idea of species, and even conceives a species to have been as numerous in individuals and as wide-spread over space, or as segregated in discontinuous spaces, from the first as at the later period.

The station which it inhabits, therefore, is with

What the Rev. Principal Tulloch remarks in respect to the phi losophy of miracles has a pertinent application here. We quote at second hand:

"The stoutest advocates of interference can mean nothing more than that the Supreme Will has so moved the hidden springs of Nature that a new issue arises on given circumstances. The ordinary issue is supplanted by a higher issue." The essential facts before us are a certain set of phenomena, and a Higher Will moving them. How moving them? is a question for human definition; the answer to which does not and cannot affect the divine meaning of the change. Yet when we reflect that this Higher Will is everywhere reason and wisdom, it seems a juster as well as a more comprehensive view to regard it as operating by subordination and evolution, rather than by interference or violation."

other naturalists in no wiso essential to the species, and may not have been the region of its origin. In Agassiz's view the habitat is supposed to mark the origin, and to be a part of the character of the species. The habitat is not merely the place where it is, but a part of what it is.

Most naturalists recognize varieties of species; and many, like De Candolle, have come to concludo that varieties of the highest grade, or races, so far partake of the characteristics of species, and are so far governed by the same laws, that it is often very dill cult to draw a clear and certain distinction between the two. Agassiz will not allow that varieties or races exist in Nature, apart from man's agency.

Most naturalists believe that the origin of species is supernatural, their dispersion or particular geographical area, natural, and their extinction, when they dise appear, also the result of physical causes. In the view of Agassiz, if rightly understood, all three are equally independent of physical cause and effect, are equally supernatural.

In comparing preceding periods with the present and with each other, most naturalists and palvontolo gists now appear to recognize a certain number of species as having survived from one epoch to the next, or even through more than one formation, especially from the Tertiary into the post-Tertiary period, and from that to the present age. Agassiz is understood to believe in total extinctions and total new creations at each successive epoch, and even to recognize no existing species as ever contemporary with extinct ones, except in the case of recent exterminations.

Thoso poculiar viows, if sustained, will effectually dispose of every form of derivative hypothesis.

Returning for a moment to De Candolle's article, wo are disposed to notice his criticism of Linnæus's "definition" of the term species (Philosophia Botanica, No. 157): "Species tot numeramus quot diversæ forma in principio sunt creata"-which he declares illogical, inapplicable, and the worst that has been propounded. "So, to determine if a form is specific, it is necessary to go back to its origin, which is impossible. A definition by a character which can never be verified is no definition at all."

Now, as Linnaeus practically applied the idea of species with a sagacity which has never been surpassed, and rarely equaled, and indeed may be said to have fixed its received meaning in natural history, it may well be inferred that in the phrase above cited he did not so much undertake to frame a logical definition, as to set forth the idea which, in his opinion, lay at the foundation of species; on which basis A. L. Jussieu did construct a logical definition-"Nunc rectius definitur perennis individuorum similium suc cessio continuata generatione renascentiun." The fundamental idea of species, we would still maintain, is that of a chain of which genetically-connected individuals are the links. That, in the practical recognition of species, the essential characteristic has to be inferred, is no great objection-the general fact that like engenders liko being an induction from a vast number of instances, and tho only assumption being that of the uniformity of Nature. The idea of gravitation, that of the atomic constitution of matter, and the like,

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