26o 



NATURE 



[July ii, 1895 



similar to that which was observed in the original case. It also 

 frequently occurs that the range of rank is found to Iw greater in 

 one or both directions than is to be observed in other cases. By 

 such means a know ledge of the order of faunal and floral, .is well 

 as of stratigraphical, succession far beyond that which could be 

 obtained in any one region, has been acquired. 



It is upon such empirical facts as these that the early geologists 

 based their investigations concerning the chronological arrange- 

 ment of the sedimentar)- formations of the earth, and the grand 

 result of which was the adoption of a general scheme and the con- 

 stniction of a corresponding scale for their classification. This 

 scale, which in its present condition is a masterpiece of inductive 

 reasoning, necessarily originated in Eurojie. l)ecause it was there 

 that geology was first systematically studied, and it is there also 

 that its adaptation is more complete than elsewhere. 



Although the scale now in use was established l)efore the truth 

 of the pri^essive evolution of oi^anic foniis was acccptefl by 

 naturalists, and when all differences between those forms was 

 t)elieved to be due to special creations, general progression in 

 average biological rank during geological time was perceived by 

 the early geologists, .-is well as by those of the present day ; 

 but with them it was the perception of a pri^essive succession in 

 rank of faunal an<l floral groups of great assemblages of organic 

 forms, and not the recognition of the principle of evolution. 

 Therefore they sought methods of explaining the facts and con- 

 cliti.ns which they observed with reference to the geological 

 x ill- which they had establishe<l that should acconl with the 

 hicLigical views which then prevailed, and which were largely of a 

 >uiK.rnatural character. Indeed, in the absence of the now- 

 prevalent natural method of explaining these facts, the 

 ~ui>ematural method of the early geolt^sts seems to have been 

 nece-v<if>-. 



The f<)llowing deductive propositions which now remind a 

 naturalist of the articles of a cree<l more than of a statement of 

 ~icrilific principles, are presented as indicating the fundamental 

 I'lii^ helil by the early geologists in connection with the con- 

 -!ri! ii.in of the geological scale, and .is illustrating the state of 

 irn.ilcnl opinion among leading geologists U|K)n biological 

 ~iii.;ccts in their time. It is true that no one author has ever 

 |)ublishe<l these pro|X6itions in the exact fonn in which they are 

 here presented, but they have been formulated from the published 

 utterances of numerous authors, and from [lersonal recollec- 

 tions of an active imrticipation in geological work tluring a 

 numlx-r of years, immeiliately preceding the great revolution in 

 methods of biological thought and investigation which has been 

 referred to. These propositions are : — 



(1) That every s|xs:ies of animals and plants, Ixjth living and 

 extinct, was sfiecially created, and that they arc, and always 

 have been immutable. That genera, and also the higher groups 

 into which both the animal and vegetable kingdoms are system- 

 atically divisible, are categories of creative thought, and that 

 they also are immutable. 



(2) That although secular extinction of certain species, and 

 even genera, occurre<l during ever)- stage of the geological scale, 

 at the close of each stage, except the Tertiary, all life ujion the 

 earth was simultaneously destroyed, and that at the close of each 

 sub-stage life was at lea.st in large |)art destroyed. 



(3) That, at the close of each st.ige oiincidently with, and the 

 • livinely ordainerl instninient of, the complete eslinction of life, 

 there was a universal physical cat.islrophe, iind that the close of 

 each sub-si,igc was, at least in ]«rt. physically catastrophic. 



(4) That all life for each successive stage was createtl anew. 



(5) That the life of each stage embraced sjx-cially ordained 

 generic, or more general, types which were distinctive of and 



I', anfl that their distribution w,is world-wide, 

 ■here was a s|>ecial ordination of char.icteristic ty[ies 

 st.ige. which received world-wide and simultaneous 

 vsilhin its narrow lime limits. 



110 i<lentical, and few similar, s|>ecific forms were 

 I !• ti'.l lilt any twn or more slage.s. 



(Si Thill rhe world-wide distribution of the di.stinctive lyjx-s 



»% hich were or<laine<l to characterise any 



cfleried in connection with the act by 



i>-and floras were created: or that 



t\ing a world-wide distrilmtion the 



.. , I'l floras was preserved by the intro- 



•11 ol rcprev:mativc--that is, cloM-ly similar — but distinct 



!9) That by rr. 

 new creation wa- 



i ihe average biological rank of each 

 ihil of the next preceding one. 



(10) That upin the fossilisable jxirts of the animals and plants 

 which were created for each stage, and U|xin those <lesigned to 

 characterise each sub-stage, was impressed not only their own 

 structural features, but reci^isable eWdence of their chrono- 

 logical ordination. 



These propositions represent only those views of the pioneer 

 geologists which pertain to biological geolc^-. Other views 

 which were held by them are unjissailable, even in the light of 

 I the present advance of science, and their biological views are 

 I not introduced here for the purpose of disixiragement, Init to 

 I show that they gave origin to certain erroneous metho<ls which 

 I are in part retaine<l as an inheritance by some (Xikvontologists, 

 I even though they ostensibly accept the principles of nu«lern 

 I biolog)-. 



I The foregoing pro|x)sitions relate to what were regarded by 

 , the early geologists as fundamental ideas in the constraction of 

 the geological scale, while the following relate to those ideas 

 I which are now held to constitute its true Kisis because they 

 only accord with natural laws. These are therefore essentially 

 a counter-statement of the precetling projKisitions ; but the 

 princi|xil object of their pre|)aration is to (Kiint out the true 

 relation of biologv' to systematic, historical, and correlative 

 I geology. They consist largely of the statement of certain of 

 the principles involved in the theory of organic evolution. Init 

 i they are by no means intended as a full statement of those prin- 

 ciples, nor are they presented for the purix)se of either discuss- 

 ing or defining then) as such. That is, the statements are made 

 not for the pur|x)se of formally enunciating these principles, but 

 for the puriwse of making practical application of them to the 

 subject in hand. Such of these have been selected for statement 

 and comment as are believed to Ik" accepted by all naturalists 

 who .idmit the truth of organic evolution, and such application 

 is made of them as will necessarily commend itself to all geologists 

 who admit that tnilh and its applicability to biological geologj. 

 These propositions are not intended to embrace the wliolc 

 range of biological geolog)-, but only such of its leading jirin- 

 ciples as are discussed in these essays. Therefore a certain lack 

 of innnediate relevancy will appear in the order in which they 

 are stated. 



(1) All species of animals and plants have originated genetic- 

 ally from pre-existing forms, and therefore all are more or le.-s 

 mutable as regards their reproduction. These, together with 

 the various divisions higher than species into which the animal 

 and vegetable kingdoms are divisible, have resjiectively aojuired 

 their distinguishing characteristics by diflerential aiul gmtlually 

 progressive evolution. The extinction of all species and other 

 divisions of the animal an<I vegetable kingdoms which has taken 

 place during geological time, h.is always been by natural means 

 and in accordance with natural laws. It has generally lieen 

 secular and gradual, but in many rases ItKally or regionally 

 accidental. No universal extinction has ever occurred. 



(2) Coincident with the progress of evolution, notwithstanding 

 the retardation, inertion, and even degrad.ition that have occurre<l 

 along certain lines, there has been during geological time a 

 general average advancement in biological rank of animal and 

 vegetable forms, evidence of which is aflforded by certain 

 characteristics of their fossil remains. The evidence of this 

 general advancement cimstitutes the ultimate standard of 

 measures of geological time as a whole, ami the princi]\il means 

 of .ascertaining the order of full succession of the events which 

 attended the prixluction of the stratified rocks of the earth. 



(3) The chronological features which fossils |>ossess are not of 

 a siwcial character as .such, but they are nnnmg those Ujxm which 

 their biological cLissification is l>.i.sed, all of which features 

 have resulted from Uilh jirogressive and diflerential evolution. 



(4I The average rate of progressive evi>Uilion for the diflerent 

 branches or divisions of lK)lh the animal and vegetable kingiloms 

 has not been the s;ime for each in all parts of the world, nor the 

 same for all in anyone giart of the worlil, during all the time 

 they have coexisted. 



(5) The rate of differential evolution among Ihe forms con- 

 stituting certain divisions of the animal and vegetable kingdoms 

 was greater than that among th<ise constituting other ilivisions ; 

 and it was greater for some of the memliers of a given division 

 uniler certain ccmditi<pns than it was for other members of the 

 same division under other conilitions. 



(6) The succession of gra<lual miilations, in Ihe development 

 of the leading classificatory features which characterise certain 

 groujis of fovsil forms, was not necessarily concurrent with ion- 

 sccnlive ixirtions of time. 



NO. 



1 34 I, VOL. 52] 



