Science Authors

"The clear and philosophical views of Fracastoro were disregarded, and the talent and argumentative powers of the learned were doomed for three centuries to be wasted in the discussion of these two simple and preliminary questions: first, whether fossil remains had ever belonged to living creatures; and secondly, whether, if this be admitted, all the phenomena could be explained by the Noachian deluge."

"It had been the consistent belief of the Christian world, down to the period now under consideration, that the origin of this planet was not more remote than a few thousand years; and that since the creation the deluge was the only great catastrophe by which considerable change had been wrought on the earth's surface. On the other hand, the opinion was scarcely less general, that the final dissolution of our system was an event to be looked for at no distant period."

"The era, it is true, of the expected millennium had passed away; and for five hundred years after the fatal hour, when the annihilation of the planet had been looked for, the monks remained in undisturbed enjoyment of rich grants of land bequeathed to them by pious donors, who, in the preamble of deeds beginning 'appropinquante mundi termino'-'appropinquante magno judicii die,' left lasting monuments of the popular delusion."

"But there was sufficient spirit of toleration and candor amongst the Italian ecclesiastics to allow the subject to be canvassed with much freedom They entered warmly themselves into the controversy often favoring different sides of the question and however much we may deplore the loss of time and labor devoted to the defense of untenable positions it must be conceded that they displayed far less polemic bitterness than certain writers who followed them beyond the Alps two centuries and a half later"

"The system of scholastic disputations encouraged in the Universities of the middle ages had unfortunately trained men to habits of indefinite argumentation, and they often preferred absurd and extravagant propositions, because greater skill was required to maintain them; the end and object of such intellectual combats being victory and not truth."

"Opponents of Fracastoro met his arguments by feigning imaginary causes, which differed from each other rather in name than in substance. Andrea Mattioli, for instance, an eminent botanist, the illustrator of Dioscorides, embraced the notion of Agricola, a German miner, that a certain 'materia pinguis' or 'fatty matter,' set into fermentation by heat, gave birth to fossil organic shapes. Yet Mattioli had come to the conclusion, from his own observations, that porous bodies, such as bones and shells, might be converted into stone, as being permeable to what he termed the 'lapidifying juice.'"

"Falloppio of Padua conceived that petrified shells had been generated by fermentation in the spots where they were found, or that they had in some cases acquired their form from 'the tumultuous movements of terrestrial exhalations.' Although a celebrated professor of anatomy, he taught that certain tusks of elephants dug up in his time at Puglia were mere earthy concretions, and, consistently with these principles, he even went so far as to consider it not improbable, that the vases of Monte Testaceo at Rome were natural impressions stamped in the soil."

"The title of a work of Cardano's, published in 1552, 'De Subtilitate' (corresponding to what would now be called Transcendental Philosophy), would lead us to expect, in the chapter on minerals, many far fetched theories characteristic of that age; but when treating of petrified shells, he decided that they clearly indicated the former sojourn of the sea upon the mountains."

"Cesalpino, a celebrated botanist, conceived that fossil shells had been left on the land by the sea, and had concreted into stone during the consolidation the soil; and in the following year (1597), Simeone Majoli went still farther, and coinciding for the most part with views of Cesalpino, suggested that the shells and matter of the Veronese, and other districts, might have cast up, upon the land, by volcanic explosions, like those gave rise, in 1538, to Monte Nuovo, near Puzzuoli.- This hint was the first imperfect attempt to connect the position fossil shells with the agency of volcanoes, a system more fully developed by Hooke, [Antonio] Lazzaro Moro, Hutton, and other writers. Two years afterwards, Imperati advocated the animal origin of fossilized shells, yet admitted that stones could vegetate by force of 'an internal principle,' and, as evidence of this, he referred to the teeth of fish, and spines of echini found petrified."

"Palissy, a French writer on 'the Origin of Springs from Rain-water' and of other scientific works, undertook, in 1580, to combat the notions of many of his contemporaries in Italy, that petrified shells had all been deposited by the universal deluge. 'He was the first,' said Fontenelle, when, in the French Academy, he pronounced his eulogy nearly a century and a half later, 'who dared assert' in Paris, that fossil remains of testacea and fish had once belonged to marine animals."

"Fabio Colonna deserves to be distinguished; for, although he gave way to the dogma that all fossil remains were to be referred to the Noachian deluge, he resisted the absurd theory of Stelluti, who taught that fossil wood and ammonites were mere clay, altered into such forms by sulfurous waters and subterranean heat; and he pointed out the different states of shells buried in the strata, distinguishing between, first, the mere mould or impression; secondly, the cast or nucleus; and thirdly, the remains of the shell itself. He had also the merit of being the first to point out, that some of the fossils had belonged to marine, and some to terrestrial testacea."

"The most remarkable work of that period was published by Steno... The treatise bears the quaint title of 'De Solido intra Solidum contento naturaliter (1669,)' by which the author intended to express 'On Gems, Crystals, and organic Petrifactions enclosed within solid Rocks.' ...Steno had compared the fossil shells with their recent analogues, and traced the various gradations from the state of mere calcification, when their natural gluten only was lost, to the perfect substitution of stony matter. He demonstrated that many fossil teeth found in Tuscany belonged to a species of shark; and he dissected, for the purpose of comparison, one of these fish recently taken from the Mediterranean. That the remains of shells and marine animals found petrified were not of animal origin was still a favorite dogma of many, who were unwilling to believe that the earth could have been inhabited by living beings long before many of the mountains were formed."

"Steno conceded, as Fabio Colonna had done before him, that all marine fossils might have been transported into their present situation at the time of the Noachian deluge. He maintained that fossil vegetables had been once living plants, and he hinted that they might, in some instances, indicate the distinction between fluvial and marine deposits. He also inferred that the present mountains had not existed ever since the origin of things, suggesting that many strata of submarine origin had been accumulated in the interval between the creation and deluge. Here he displayed his great anxiety to reconcile his theory with the Scriptures; for he at the same time advanced an opinion, which does not seem very consistent with such a doctrine, viz., that there was a wide distinction between the shelly, and nearly horizontal beds at the foot of the Apennines, and the older mountains of highly inclined stratification. Both, he observed, were of sedimentary origin; and a considerable interval of time must have separated their formation. Tuscany, according to him, had successively passed through six different states; and to explain these mighty changes, he called in the agency of inundations, earthquakes, and subterranean fires."

"Scarcely any step had been made in approximating to sound theories since the time of Fracastoro, more than a hundred years having been lost, in writing down the dogma that organized fossils were mere sports of nature. An additional period of a century and a half was now destined to be consumed in exploding the hypothesis, that organized fossils had all been buried in the solid strata by the Noachian flood. Never did a theoretical fallacy, in any branch of scienc, interfere more seriously with accurate observation and the systematic classification of facts."

"The old diluvialists were induced by their system to confound all the groups of strata together instead of discriminating,—to refer all appearances to one cause and to one brief period, not to a variety of causes acting throughout a long succession of epochs. ...Under the influence of such prejudices, three centuries were of as little avail, as a few years in our own times, when we are no longer required to propel the vessel against the force of an adverse current."

"It may be well to forewarn our readers that in tracing the history of geology from the close of the seventeenth to the end of the eighteenth century they must expect to be occupied with accounts of the retardation as well as of the advance of the science. ...It will be necessary to dwell on futile reasoning and visionary hypothesis because the most extravagant systems were often invented or controverted by men of acknowledged talent."

"A sketch of the progress of Geology is the history of a constant and violent struggle between new opinions and ancient doctrines sanctioned by the implicit faith of many generations and supposed to rest on scriptural authority. The inquiry, therefore, although highly interesting to one who studies the philosophy of the human mind, is singularly barren of instruction to him who searches for truths in physical science."

"Quirini, in 1676, contended in opposition to Scilla, that the diluvian waters could not have conveyed heavy bodies to the summit of mountains, since the agitation of the sea never (as Boyle had demonstrated) extended to great depths, and still less could the testacea, as some pretended, have lived in these diluvian waters, for 'the duration of the flood was brief, and the heavy rains must have destroyed the saltness of the sea! He was the first writer who ventured to maintain that the universality of the Noachian cataclysm ought not to be insisted upon. ...Visionary as was this doctrine, it gained many proselytes even amongst the more sober reasoners of Italy and Germany, for it conceded both that fossil bodies were organic, and that the diluvial theory could not account for them."

"Dr. Plot, in his 'Natural History of Oxfordshire.' (1677) attributed to a 'plastic virtue latent in the earth' the origin of fossil shells and fishes; and Lister, to his accurate account of British shells, in 1678, added the fossil species, under the appellation of turbinated and bivalve stones. 'Either,' said he, 'these were terriginous, or if otherwise, the animals they so exactly represent have become extinct. This writer appears to have been the first who was aware of the continuity over large districts of the principal groups of strata in the British series, and who proposed the construction of regular geological maps."

"'The Posthumous Works of Robert Hooke M.D.,'... appeared in 1705, containing 'A Discourse of Earthquakes'... His treatise... is the most philosophical production of that age, in regard to the causes of former changes in the organic and inorganic kingdoms of nature. 'However trivial a thing,' he says, 'a rotten shell may appear to some, yet these monuments of nature are more certain tokens of antiquity than coins or medals, since the best of those may be counterfeited or made by art and design, as may also books, manuscripts, and inscriptions, as all the learned are now sufficiently satisfied has often been actually practised,' &c.; 'and though it must be granted that it is very difficult to read them and to raise a chronology out of them, and to state the intervals of the time wherein such or such catastrophes and mutations have happened, yet it is not impossible."

"Respecting the extinction of species, Hooke was aware that the fossil ammonites, nautili, and many other shells and fossil skeletons found in England, were of different species from any then known; but he doubted whether the species had become extinct, observing that the knowledge of naturalists of all the marine species, especially those inhabiting the deep sea, was very deficient. In some parts of his writings, however, he leans to the opinion that species had been lost; and in speculating on this subject, he even suggests that there might be some connection between the disappearance of certain kinds of animals and plants, and the changes wrought by earthquakes in former ages. Some species, he observes with great sagacity, are peculiar to certain places, and not to be found elsewhere. If, then, such a place had been swallowed up, it is not improbable but that those animate beings may have been destroyed with it; and this may be true both of aerial and aquatic animals: for those animated bodies, whether vegetables or animals, which were naturally nourished or refreshed by the air, would be destroyed by the water, &c. Turtles, he adds, and such large ammonites as are found in Portland, seem to have been the productions of the seas of hotter countries, and it is necessary to suppose that England once lay under the sea within the torrid zone! To explain this and similar phenomena, he indulges in a variety of speculations concerning changes in the position of the axis of the earth's rotation, a shifting of the earth's center of gravity, 'analogous to the revolutions of the magnetic pole,' &c. None of these conjectures, however, are proposed dogmatically, but rather in the hope of promoting fresh inquiries and experiments."

"It was objected to Hooke, that his doctrine of the extinction of species derogated from the wisdom and power of the Omnipotent Creator; but he answered, that as individuals die, there may be some termination to the duration of a species; and his opinions, he declared, were not repugnant to Holy Writ: for the Scriptures taught that our system was degenerating, and tending to its final dissolution; 'and as, when that shall happen, all the species will be lost, why not some at one time and some at another?'"

"His [Hooke's] principal object was to account for the manner in which shells had been conveyed into the higher parts of 'the Alps, Apennines, and Pyrenean hills, and the interior of continents in general.' These and other appearances, he said, might have been brought about by earthquakes, 'which have turned plains into mountains, and mountains into plains, seas into land, and land into seas, made rivers where there were none before, and swallowed up others that formerly were, &c. &c.; and which, since the creation of the world, have wrought many great changes on the superficial parts of the earth, and have been the instruments of placing shells, bones, plants, fishes, and the like, in those places, where, with much astonishment, we find them.' This doctrine, it is true, had been laid down in terms almost equally explicit by Strabo, to explain the occurrence of fossil shells in the interior of continents, and to that geographer, and other writers of antiquity, Hooke frequently refers; but the revival and development of the system was an important step in the progress of modern science."

"Hooke enumerated all the examples known to him of subterranean disturbance, from 'the sad catastrophe of Sodom and Gomorrah' down to the Chilean earthquake of 1646. The elevating of the bottom of the sea, the sinking and submersion of the land, and most of the inequalities of the earth's surface, might, he said, be accounted for by the agency of these subterranean causes. He mentions that the coast near Naples was raised during the eruption of Monte Nuovo; and that in 1591, land rose in the island of St. Michael, during an eruption; and although it would be more difficult, he says, to prove, he does not doubt but that there had been as many earthquakes in the parts of the earth under the ocean, as in the parts of the dry land; in confirmation of which he mentions the immeasurable depth of the sea near some volcanoes. To attest the extent of simultaneous subterranean movements, he refers to an earthquake in the West Indies, in 1690, where the space of earth raised, or 'struck upwards' by the shock, exceeded the length of the Alps and the Pyrenees."

"As Hooke declared the favorite hypothesis of the day ('that marine fossil bodies were to be referred to Noah's flood') to be wholly untenable, he appears to have felt himself called upon to substitute a diluvial theory of his own, and thus he became involved in countless difficulties and contradictions. ...When ...he required a former 'crisis of nature' and taught that earthquakes had become debilitated, and that the Alps, Andes, and other chains, had been lifted up in a few months, his machinery was as extravagant and visionary as that of his most fanciful predecessors; and for this reason, perhaps, his whole theory of earthquakes met with undeserved neglect."

"Leibnitz, the great mathematician, published his 'Protogaea' in 1680. He imagined this planet to have been originally a burning luminous mass, and that ever since its creation it has been undergoing gradual refrigeration. Nearly all the matter of the earth was at first encompassed by fire. When the outer crust had at length cooled down sufficiently to allow the vapors to be condensed, they fell and formed a universal ocean, investing the globe, and covering the loftiest mountains. Further consolidation produced rents, vacuities, and subterranean caverns, and the ocean, rushing in to fill them, was gradually lowered. The principal feature of this theory, the gradual diminution of the original heat, and of an ancient universal ocean, were adopted by Buffon and De Luc, and entered under different modifications, into a great number of succeeding systems."

"Now, if it would be reasonable to draw such inferences with respect to"

"So long as physiologists continued to believe that man had not existed on the earth above six thousand years, they might, with good reason, withhold their assent from the doctrine of a unity of origin of so many distinct races; but the difficulty becomes less and less, exactly in proportion as we enlarge our ideas of the lapse of time during which different communities may have spread slowly, and become isolated, each exposed for ages to a peculiar set of conditions, whether of temperature, or food, or danger, or ways of living."

"If, in spite of the fact that all these attributes have been faithfully handed down unaltered for hundreds of generations, we are to believe that, in the course of time, they have all diverged from one common stock, how shall we resist the arguments of the transmutationist, who contends that all closely allied species of animals and plants have in like manner sprung from a common parentage, albeit that for the last three or four thousand years they may have been persistent in character?"

"So long as Geology had not lifted up a part of the veil... it was easy to treat these questions as too transcendental... But it is no longer possible to restrain curiosity from attempting to pry into the relations which connect the present state of the animal and vegetable worlds, as well as of the various races of mankind, with the state of the fauna and flora which immediately preceded."

"What Lamarck then foretold has come to pass; the more new forms have been multiplied, the less are we able to decide what we mean by a variety, and what by a species. In fact, zoologists and botanists are not only more at a loss than ever how to define a species, but even to determine whether it has any real existence in nature, or is a mere abstraction of the human intellect, some contending that it is constant within certain narrow and impassable limits of variability, others that it is capable of indefinite and endless modification."

"Lamarck, after having first studied botany with success, had then turned his attention to conchology, and soon became aware that in the newer (or tertiary) strata of the earth's crust there were a multitude of fossil species of shells... He also observed that other shells were so nearly allied to living forms, that it was difficult not to suspect that they had been connected by a common bond of descent. He therefore proposed that the element of time should enter into the definition of a species, and that it should run thus: 'A species consists of individuals all resembling each other, and reproducing their like by generation, so long as the surrounding conditions do not undergo changes sufficient to cause their habits, characters, and forms to vary. He came at last to the conclusion, that none of the animals and plants now existing were primordial creations, but were all derived from pre-existing forms, which, after they may have gone on for indefinite ages reproducing their like, had, at length, by the influence of alterations in climate and in the animate world, been made to vary gradually, and adapt themselves to new circumstances, some of them deviating, in the course of ages, so far from their original type as to have claims to be regarded as new species."

"Lamarck taught not only that species had been constantly undergoing changes from one geological period to another, but that there also had been a progressive advance of the organic world from the earliest to the latest times, from beings of the simplest to those of more and more complex structure and from the lowest instincts up to the highest, and, finally, from brute intelligence to the reasoning powers of Man. The improvement in the grade of being had been slow and continuous, and the human race itself was at length evolved out of the most highly organised and endowed of the inferior mammalia."

"I pointed out in 1832, as the two great flaws in Lamarck's attempt to explain the origin of species, first that he had failed to adduce a single instance of the initiation of a new organ in any species of animal or plant; and secondly, that variation, whether taking place in the course of nature or assisted artificially by the breeder and horticulturist, had never yet gone so far as to produce two races sufficiently remote from each other in physiological constitution as to be sterile when intermarried, or, if fertile, only capable of producing sterile hybrids, &c."

"In my account of his [Lamarck's] theory, I did not, at the time, fully appreciate the deep conviction which it displays of the slow manner in which geological changes have taken place, and the insignificance of thirty or forty centuries in the history of a species, and that, too, at a period when very narrow views were entertained of the extent of past time by most of the ablest geologists, and when great revolutions of the earth's crust, and its inhabitants, were generally attributed to sudden and violent catastrophes."

"I endeavoured to sketch out (and it was, I believe, the first systematic attempt to accomplish such a task) the laws which govern the extinction of species, with a view of showing that the slow, but ceaseless variations, now in progress in physical geography, together with the migration of plants and animals into new regions, must, in the course of ages, give rise to the occasional loss of some of them, and eventually cause an entire fauna and flora to die out; also, that we must infer, from geological data, that the places thus left vacant from time to time, are filled up without delay by new forms, adapted to new conditions, sometimes by immigration from adjoining provinces, sometimes by new creations. Among the many causes of extinction enumerated by me, were the power of hostile species, diminution of food, mutations in climate, the conversion of land into sea, and of sea into land, &c."

"The doctrine of progression... was thus given twelve years ago by Professor Sedgwick, in the preface to his Discourse on the Studies of the University of Cambridge. 'There are traces,' he says, 'among the old deposits of the earth of an organic progression among the successive forms of life. They are to be seen in the absence of mammalia in the older, and their very rare appearance in the newer secondary groups; in the diffusion of warm blooded quadrupeds (frequently of unknown genera) in the older tertiary system, and in their great abundance (and frequently of known genera) in the upper portions of the same series; and lastly, in the recent appearance of Man on the surface of the earth.' 'This historical development,' continues the same author, 'of the forms and functions of organic life during successive epochs, seems to mark a gradual evolution of creative power, manifested by a gradual ascent towards a higher type of being.' 'But the elevation of the fauna of successive periods was not made by transmutation, but by creative additions; and it is by watching these additions that we get some insight into Nature's true historical progress, and learn that there was a time when Cephalopoda were the highest types of animal life, the primates of this world; that Fishes next took the lead, then Reptiles; and that during the secondary period they were anatomically raised far above any forms of the reptile class now living in the world. Mammals were added next, until Nature became what she now is, by the addition of Man. ...the generalisation, as laid down by the Woodwardian Professor, still holds good in all essential particulars."

"It may be thought almost paradoxical that writers who are most in favour of transmutation (Mr. C. Darwin and Dr. J. Hooker, for example) are nevertheless among those who are most cautious, and one would say timid, in their mode of espousing the doctrine of progression; while, on the other hand, the most zealous advocates of progression are oftener than not very vehement opponents of transmutation."

"No one can believe in transmutation who is not profoundly convinced that all we know in paleontology is as nothing compared to what we have yet to learn, and they who regard the record as so fragmentary, and our acquaintance with the fragments which are extant as so rudimentary, are apt to be astounded at the confidence placed by the progressionists in data which must be defective in the extreme. But exactly in proportion as the completeness of the record and our knowledge of it are overrated, in that same degree are many progressionists unconscious of the goal towards which they are drifting. Their faith in the fullness of the annals leads them to regard all breaks in the series of organic existence, or in the sequence of the fossiliferous rocks, as proofs of original chasms and leaps in the course of nature, signs of the intermittent action of the creational force, or of catastrophes which devastated the habitable surface; and they are therefore fearless of discovering any continuity of plan (except that which must have existed in the Divine mind) which would imply a material connection between the outgoing organisms and the incoming ones."

"For many years after the promulgation of Lamarck's doctrine of progressive development, geologists were much occupied with the question whether the past changes in the animate and inanimate world were brought about by sudden and paroxysmal action, or gradually and continuously by causes differing neither in kind nor degree from those now in operation."

"The anonymous author of 'The Vestiges of Creation' published in 1844 a treatise, written in a clear and attractive style, which made the English public familiar with the leading views of Lamarck on transmutation and progression but brought no new facts or original line of argument to support those views, or to combat the principal objections which the scientific world entertained against them. No decided step in this direction was made until the publication in 1858 of two papers, one by Mr. Darwin and another by Mr. Wallace, followed in 1859 by Mr Darwin's celebrated work on 'The Origin of Species by Means of Natural Selection; or, the Preservation of favoured Races in the Struggle for Life.' ...both writers begin by applying to the animal and vegetable worlds the Malthusian doctrine of population, or its tendency to increase in a geometrical ratio, while food can only be made to augment even locally in an arithmetical one. There being, therefore, no room or means of subsistence for a large proportion of the plants and animals which are born into the world, a great number must annually perish."

"As breeders of domestic animals, when they choose certain varieties in preference to others to breed from, speak technically of their method as that of 'selecting,' Mr. Darwin calls the combination of natural causes, which may enable certain varieties of wild animals or plants to prevail over others of the same species, 'natural selection.'"

"Lamarck, when speculating on the origin of the long neck of the giraffe, imagined that quadruped to have stretched himself up in order to reach the boughs of lofty trees, until by continued efforts, and longing to reach higher, he obtained an elongated neck. Mr. Darwin and Mr. Wallace simply suppose that, in a season of scarcity, a longer-necked variety, having the advantage in this respect over most of the herd, as being able to browse on foliage out of their reach, survived them, and transmitted its peculiarity of cervical conformation to its successors."

"By the multiplying of slight modifications in the course of thousands of generations, and by the handing down of the newly-acquired peculiarities by inheritance, a greater and greater divergence from the original standard is supposed to be effected, until what may be called a new species, or, in a greater lapse of time, a new genus, will be the result."

"Every naturalist admits that there is a general tendency in animals and plants to vary; but it is usually taken for granted, though we have no means of proving the assumption to be true, that there are certain limits beyond which each species cannot pass under any circumstances, or in any number of generations. Mr. Darwin and Mr. Wallace say that the opposite hypothesis, which assumes that every species is capable of varying indefinitely from its original type, is not a whit more arbitrary, and has this manifest claim to be preferred, that it will account for a multitude of phenomena which the ordinary theory is incapable of explaining."

"The competition of races and species, observes Mr. Darwin, is always most severe between those which are most closely allied and which fill nearly the same place in the economy of nature. Hence, when the conditions of existence are modified, the original stock runs great risk of being superseded by some one of its modified offshoots. The new race or species may not be absolutely superior in the sum of its powers and endowment to the parent stock, and may even be more simple in structure and of a lower grade of intelligence, as well as of organisation, provided, on the whole, it happens to have some slight advantage over its rivals. Progression, therefore, is not a necessary accompaniment of variation and natural selection, though, when a higher organisation happens to be coincident with superior fitness to new conditions, the new species will have greater power and a greater chance of permanently maintaining and extending its ground."

"One of the principal claims of Mr. Darwin's theory to acceptance is, that it enables us to dispense with a law of progression as a necessary accompaniment of variation. It will account equally well for what is called degradation, or a retrograde movement towards a simpler structure, and does not require Lamarck's continual creation of monads; for this was a necessary part of his system, in order to explain how, after the progressive power had been at work for myriads of ages, there were as many beings of the simplest structure in existence as ever."

"Mr. Darwin labours to show, and with no small success, that all true classification in zoology and botany is, in fact, genealogical, and that community of descent is the hidden bond which naturalists have been unconsciously seeking, while they often imagined that they were looking for some unknown plan of creation."

"It [variation and natural selection] would explain, says Mr. Darwin, the unity of type which runs through the whole organic world, and why there is sometimes a fundamental agreement in structure in the same class of beings which is quite independent of their habits of life, for such structure, derived by inheritance from a remote progenitor, has been modified, in the course of ages, in different ways, according to the conditions of existence. It would also explain why all living and extinct beings are united, by complex radiating and circuitous lines of affinity with one another, into one grand system; also, there having been a continued extinction of old races and species in progress, and a formation of new ones by variation, why in some genera which are largely represented, or to which a great many species belong, many of these are closely but unequally related; also, why there are distinct geographical provinces of species of animals and plants, for, after long isolation by physical barriers, each fauna and flora, by varying continually, must become distinct from its ancestral type, and from the new forms assumed by other descendants which have diverged from the same stock."

"Variation and natural selection would also afford a key to a multitude of geological facts otherwise wholly unaccounted for, as, for example, why there is generally an intimate connection between the living animals and plants of each great division of the globe and the extinct fauna and flora of the post-tertiary or tertiary formations of the same region..."