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Show 4G4 RECAPITULATIO~. CHAP. XIV. strata must somewhere have been deposited at these ancient and utterly unknown epochs in the world's history. I can answer these questions and grave objections only on the supposition that the geological record is far more imperfect than most geologists believe. It cannot be objected that there has not been time sufficient for any amount of organic change; for the lapse of time has been so great as to be utterly inappreciable by the human intellect. The number of specimens in all our museums is absolutely as nothing compared with the countless generations of countless species which certainly have existed. We should not be able to recognise a species as the parent of any one or more species if we were to examine them ever so closely, unless we likewise possessed many of the intermediate links between their past or parent and present states; and these many links we could hardly ever expect to discover, owing to the imperfection of the geological record. Numerous existing doubtful forms could be named which are probably varieties; but who will pretend that in future ages so many fossil links will be discovered, that naturalists will be able to decide, on the common view, whether or not these doubtful forms are varieties? As long as most of the links between any two species are unknown, if any one link or intermediate variety be discovered, it will simply be classed as another and distinct species. Only a small portion of the world has been geologically explored. Only organic beings of certain classes can be preserved in a fossil condition, at least in any great number. Widely ranging species vary most, and varieties are often at first local,-both causes rendering the discovery of intermediate links less likely. Local varieties will not spread into other and distant regions until they are considerably modified and im- CHAP. XIV. RECAPITULATION. 4.65 proIv ed·; and when they do spread I'f d' d . 1 . ' Iscovere In a geo ogiCa formation_, they will appear as if sudden! created there, and will be simply classed as . Y ~1 .(! • new species. ost 10rmatwns have been intermittent . th . I . In err ac-cumu atwn ; and their duration, I am inclined to believe, has been shorte~ than the average duration of specific forms. Successive formations are separated from each other by enormous blank intervals of time . .(!0 .(! 'li .(! .(! • , 11 r 10SSI - 1erous . 10rmatwns, thick enough to resist future de-gradati_ on, can .be accumulated only where much sediment IS deposited on the subsiding bed of the D . h 1 sea. uring t e a ternate periods of elevation and of station-ary level the record will be blank. During these latt periods th~re will probably be more variability in t~: f?rm~ of hfe; dunng periods of subsidence, more extinction. With respect to the absence of fossiliferous formations beneath the !ow~st S~urian strata, I can only recur to the h~pothesis gi~en. In the ninth chapter. That the ?'e~lo?ICal record IS Imperfect all will admit; but that It I~ n~.perfect to the degree which I require, few will be Inclined to admit. If we look to long enough intervals of time, geology plainly declares that all species ha:e changed ; and they have changed in the manner whiC~ my theory requires, for they have changed slowly and In . a gra~uated manner. We clearly see this in the fossil remams from consecutive formations invariably being much more closely related to each other than are the fossils from formations distant from each other in time. . Such. is th~ sum of the several chief objections and dtfficult1es which ma! justly be urged against my theory; and I have now briefly recapitulated the answers and explanations which can be given to them. I have felt these difficulties far too heavily during many years to x3 |