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Show 198 DAR WINIANA. the basis of the actual arborescent vegetation. Espe-m. a lly "a very considerable number o.f fo.r mAs nea.r ly identical with tertiary forms now exist m menca, where they have found, more easily than in our [European J soil-less vast and less extended southwardrefuge from ulterior revolutions." The extinction of species is attributed to two kinds of cau~es; the one material or physical, whether slow or rapid; the other m· he r ent in the nature of organic beings, ince.ss.an t, b t slow in a manner latent, but somehow ass1gmng t u the sp' ecies as to the individuals, a limi. ted per1.0 d 0 ' • b of existence, and, in some equally mystenous ut wholly natural way, connected with the develo~ment of organic types: 4' 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 de-parture." In this community of types, no less than in the community of certain existing species, Saporta recognizes a prolonged material union between North. America and Europe in former times. Most naturahsts and geologists reason in the same way-some more cau- . tiously than others-yet per~aps most ?f them seem not to perceive how far such Inferences 1m~ly the doctrine of the common origin of related spemes. · 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 s~en to have been rapid and great; yet to us not ~nexpect~d. We note, also, an evident disposition, notwithstandmg SPECIES AS TO VARIATION, ETC. 199 some endeavors to the contrary, to allow derivative hypo~heses to stand or fall upon their own merits-to have Indeed upon philosophical grounds certain presumptions in their favor-and to be perhaps quite a capable of being turned to good ac;ount as ~0 bad ac~ count in natural theology.1 Amo~g the le~ding naturalists, indeed, such views -taken 1n the widest sense-have one and, so far as we are now aware, only one thoroughgoing and thoroughly consistent opponent, viz., Mr. Agassiz. Most. nn.tural~s~s take into their very conception of a spemes, exphmtly or by implication, the notion of a material connection resulting from the descent of the individuals composing it frorp a common stock of local origin. Agassiz wholly eliminates commu~ity 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 £.rst as at the later period. The station which it inhabits, therefore, is with 1 What the Rev. Principal Tulloch remarks in respect to the philosophy 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 supplante~ by a higher issue. The essential facts before us are a certain set.ofpheno:nena, 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 reflec~ that this Higher Will is everywhere reason and wisdom, it aeems. a JUSter as well as a more comprehensive view to regard it as oper.atmg by subordination and evolution, rather than by interference or VIolation." |