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Title: The Origin of Species

From 'The Westminster Review', April 1860 Author: Thomas H Huxley

Release Date: January 6, 2009 [EBook

#2929]

Language: English

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THE ORIGIN OF SPECIES ***

Produced by Amy E Zelmer, and David Widger

THE ORIGIN OF

SPECIES

From 'The Westminster Review', April

1860.

[1]

By Thomas H Huxley

MR DARWIN'S long-standing andwell-earned scientific eminence probablyrenders him indifferent to that socialnotoriety which passes by the name ofsuccess; but if the calm spirit of thephilosopher have not yet whollysuperseded the ambition and the vanity ofthe carnal man within him, he must be

well satisfied with the results of hisventure in publishing the 'Origin ofSpecies' Overflowing the narrow bounds

of purely scientific circles, the "speciesquestion" divides with Italy and theVolunteers the attention of general society.Everybody has read Mr Darwin's book,

or, at least, has given an opinion upon itsmerits or demerits; pietists, whether lay orecclesiastic, decry it with the mild railingwhich sounds so charitable; bigotsdenounce it with ignorant invective; oldladies of both sexes consider it adecidedly dangerous book, and evensavants, who have no better mud to throw,quote antiquated writers to show that itsauthor is no better than an ape himself;while every philosophical thinker hails it

as a veritable Whitworth gun in the

armoury of liberalism; and all competentnaturalists and physiologists, whatevertheir opinions as to the ultimate fate of thedoctrines put forth, acknowledge that thework in which they are embodied is asolid contribution to knowledge andinaugurates a new epoch in natural history.Nor has the discussion of the subjectbeen restrained within the limits ofconversation When the public is eagerand interested, reviewers must minister toits wants; and the genuine 'litterateur' istoo much in the habit of acquiring hisknowledge from the book he judges—asthe Abyssinian is said to provide himselfwith steaks from the ox which carries him

—to be withheld from criticism of aprofound scientific work by the mere want

of the requisite preliminary scientificacquirement; while, on the other hand, themen of science who wish well to the newviews, no less than those who disputetheir validity, have naturally soughtopportunities of expressing their opinions.Hence it is not surprising that almost allthe critical journals have noticed Mr.Darwin's work at greater or less length;and so many disquisitions, of every degree

of excellence, from the poor product ofignorance, too often stimulated byprejudice, to the fair and thoughtful essay

of the candid student of Nature, haveappeared, that it seems an almost hopelesstask to attempt to say anything new uponthe question

But it may be doubted if the knowledge

and acumen of prejudged scientificopponents, or the subtlety of orthodoxspecial pleaders, have yet exerted theirfull force in mystifying the real issues ofthe great controversy which has been setafoot, and whose end is hardly likely to beseen by this generation; so that, at thiseleventh hour, and even failing anythingnew, it may be useful to state afresh thatwhich is true, and to put the fundamentalpositions advocated by Mr Darwin insuch a form that they may be grasped bythose whose special studies lie in otherdirections And the adoption of this coursemay be the more advisable, because,notwithstanding its great deserts, andindeed partly on account of them, the'Origin of Species' is by no means an easybook to read—if by reading is implied the

full comprehension of an author's meaning.

We do not speak jestingly in saying that

it is Mr Darwin's misfortune to knowmore about the question he has taken upthan any man living Personally andpractically exercised in zoology, in minuteanatomy, in geology; a student ofgeographical distribution, not on maps and

in museums only, but by long voyages andlaborious collection; having largelyadvanced each of these branches ofscience, and having spent many years ingathering and sifting materials for hispresent work, the store of accuratelyregistered facts upon which the author ofthe 'Origin of Species' is able to draw atwill is prodigious

But this very superabundance of matter

must have been embarrassing to a writerwho, for the present, can only put forward

an abstract of his views; and thence itarises, perhaps, that notwithstanding theclearness of the style, those who attemptfairly to digest the book find much of it asort of intellectual pemmican—a mass offacts crushed and pounded into shape,rather than held together by the ordinarymedium of an obvious logical bond; dueattention will, without doubt, discover thisbond, but it is often hard to find

Again, from sheer want of room, muchhas to be taken for granted which mightreadily enough be proved; and hence,while the adept, who can supply themissing links in the evidence from his ownknowledge, discovers fresh proof of the

singular thoroughness with which alldifficulties have been considered and allunjustifiable suppositions avoided, atevery reperusal of Mr Darwin's pregnantparagraphs, the novice in biology is apt tocomplain of the frequency of what hefancies is gratuitous assumption.

Thus while it may be doubted if, forsome years, any one is likely to becompetent to pronounce judgment on allthe issues raised by Mr Darwin, there isassuredly abundant room for him, who,assuming the humbler, though perhaps asuseful, office of an interpreter between the'Origin of Species' and the public,contents himself with endeavouring topoint out the nature of the problems which

it discusses; to distinguish between the

ascertained facts and the theoretical viewswhich it contains; and finally, to show theextent to which the explanation it offerssatisfies the requirements of scientificlogic At any rate, it is this office which

we purpose to undertake in the followingpages

It may be safely assumed that ourreaders have a general conception of thenature of the objects to which the word

"species" is applied; but it has, perhaps,occurred to a few, even to those who arenaturalists 'ex professo', to reflect, that, ascommonly employed, the term has adouble sense and denotes two verydifferent orders of relations When wecall a group of animals, or of plants, aspecies, we may imply thereby, either that

all these animals or plants have somecommon peculiarity of form or structure;

or, we may mean that they possess somecommon functional character That part ofbiological science which deals with formand structure is called Morphology—thatwhich concerns itself with function,Physiology—so that we may convenientlyspeak of these two senses, or aspects, of

"species"—the one as morphological, theother as physiological Regarded from theformer point of view, a species is nothingmore than a kind of animal or plant, which

is distinctly definable from all others, bycertain constant, and not merely sexual,morphological peculiarities Thus horsesform a species, because the group ofanimals to which that name is applied isdistinguished from all others in the world

by the following constantly associatedcharacters They have—1, A vertebralcolumn; 2, Mammae; 3, A placentalembryo; 4, Four legs; 5, A single well-developed toe in each foot provided with

a hoof; 6, A bushy tail; and 7, Callosities

on the inner sides of both the fore and thehind legs The asses, again, form a distinctspecies, because, with the samecharacters, as far as the fifth in the abovelist, all asses have tufted tails, and havecallosities only on the inner side of thefore-legs If animals were discoveredhaving the general characters of the horse,but sometimes with callosities only on thefore-legs, and more or less tufted tails; oranimals having the general characters ofthe ass, but with more or less bushy tails,and sometimes with callosities on both

pairs of legs, besides being intermediate

in other respects—the two species wouldhave to be merged into one They could nolonger be regarded as morphologicallydistinct species, for they would not bedistinctly definable one from the other

However bare and simple thisdefinition of species may appear to be, weconfidently appeal to all practicalnaturalists, whether zoologists, botanists,

or palaeontologists, to say if, in the vastmajority of cases, they know, or mean toaffirm anything more of the group ofanimals or plants they so denominate thanwhat has just been stated Even the mostdecided advocates of the receiveddoctrines respecting species admit this

"I apprehend," says Professor Owen 2,

"that few naturalists nowadays, indescribing and proposing a name for whatthey call 'a new species,' use that term tosignify what was meant by it twenty orthirty years ago; that is, an originallydistinct creation, maintaining its primitivedistinction by obstructive generativepeculiarities The proposer of the newspecies now intends to state no more than

he actually knows; as, for example, thatthe differences on which he founds thespecific character are constant inindividuals of both sexes, so far asobservation has reached; and that they arenot due to domestication or to artificiallysuperinduced external circumstances, or toany outward influence within hiscognizance; that the species is wild, or issuch as it appears by Nature."

If we consider, in fact, that by far thelargest proportion of recorded existingspecies are known only by the study oftheir skins, or bones, or other lifelessexuvia; that we are acquainted with none,

or next to none, of their physiologicalpeculiarities, beyond those which can bededuced from their structure, or are open

to cursory observation; and that we cannothope to learn more of any of those extinctforms of life which now constitute noinconsiderable proportion of the knownFlora and Fauna of the world: it isobvious that the definitions of thesespecies can be only of a purely structural,

or morphological, character It is probablethat naturalists would have avoided muchconfusion of ideas if they had morefrequently borne the necessary limitations

of our knowledge in mind But while itmay safely be admitted that we areacquainted with only the morphologicalcharacters of the vast majority of species

—the functional or physiological,peculiarities of a few have been carefullyinvestigated, and the result of that studyforms a large and most interesting portion

of the physiology of reproduction

The student of Nature wonders the moreand is astonished the less, the moreconversant he becomes with heroperations; but of all the perennialmiracles she offers to his inspection,perhaps the most worthy of admiration isthe development of a plant or of an animalfrom its embryo Examine the recently laidegg of some common animal, such as a

salamander or newt It is a minutespheroid in which the best microscopewill reveal nothing but a structureless sac,enclosing a glairy fluid, holding granules

in suspension But strange possibilities liedormant in that semi-fluid globule Let amoderate supply of warmth reach itswatery cradle, and the plastic matterundergoes changes so rapid, yet so steadyand purposelike in their succession, thatone can only compare them to thoseoperated by a skilled modeller upon aformless lump of clay As with aninvisible trowel, the mass is divided andsubdivided into smaller and smallerportions, until it is reduced to anaggregation of granules not too large tobuild withal the finest fabrics of thenascent organism And, then, it is as if a

delicate finger traced out the line to beoccupied by the spinal column, andmoulded the contour of the body; pinching

up the head at one end, the tail at the other,and fashioning flank and limb into duesalamandrine proportions, in so artistic away, that, after watching the process hour

by hour, one is almost involuntarilypossessed by the notion, that some moresubtle aid to vision than an achromatic,would show the hidden artist, with hisplan before him, striving with skilfulmanipulation to perfect his work

As life advances, and the youngamphibian ranges the waters, the terror ofhis insect contemporaries, not only are thenutritious particles supplied by its prey,

by the addition of which to its frame,

growth takes place, laid down, each in itsproper spot, and in such due proportion tothe rest, as to reproduce the form, thecolour, and the size, characteristic of theparental stock; but even the wonderfulpowers of reproducing lost partspossessed by these animals are controlled

by the same governing tendency Cut offthe legs, the tail, the jaws, separately orall together, and, as Spallanzani showedlong ago, these parts not only grow again,but the redintegrated limb is formed on thesame type as those which were lost Thenew jaw, or leg, is a newt's, and never byany accident more like that of a frog What

is true of the newt is true of every animaland of every plant; the acorn tends to builditself up again into a woodland giant such

as that from whose twig it fell; the spore

of the humblest lichen reproduces thegreen or brown incrustation which gave itbirth; and at the other end of the scale oflife, the child that resembled neither thepaternal nor the maternal side of the housewould be regarded as a kind of monster.

So that the one end to which, in allliving beings, the formative impulse istending—the one scheme which theArchaeus of the old speculators strives tocarry out, seems to be to mould theoffspring into the likeness of the parent It

is the first great law of reproduction, thatthe offspring tends to resemble its parent

or parents, more closely than anythingelse

Science will some day show us howthis law is a necessary consequence of the

more general laws which govern matter;but, for the present, more can hardly besaid than that it appears to be in harmonywith them We know that the phenomena

of vitality are not something apart fromother physical phenomena, but one withthem; and matter and force are the twonames of the one artist who fashions theliving as well as the lifeless Hence livingbodies should obey the same great laws asother matter—nor, throughout Nature, isthere a law of wider application than this,that a body impelled by two forces takesthe direction of their resultant But livingbodies may be regarded as nothing butextremely complex bundles of forces held

in a mass of matter, as the complex forces

of a magnet are held in the steel by itscoercive force; and, since the differences

of sex are comparatively slight, or, inother words, the sum of the forces in eachhas a very similar tendency, theirresultant, the offspring, may reasonably beexpected to deviate but little from acourse parallel to either, or to both.

Represent the reason of the law toourselves by what physical metaphor oranalogy we will, however, the greatmatter is to apprehend its existence andthe importance of the consequencesdeducible from it For things which arelike to the same are like to one another;and if; in a great series of generations,every offspring is like its parent, itfollows that all the offspring and all theparents must be like one another; and that,given an original parental stock, with the

opportunity of undisturbed multiplication,the law in question necessitates theproduction, in course of time, of anindefinitely large group, the whole ofwhose members are at once very similarand are blood relations, having descendedfrom the same parent, or pair of parents.The proof that all the members of anygiven group of animals, or plants, had thusdescended, would be ordinarilyconsidered sufficient to entitle them to therank of physiological species, for mostphysiologists consider species to bedefinable as "the offspring of a singleprimitive stock."

But though it is quite true that all thosegroups we call species 'may', according tothe known laws of reproduction, have

descended from a single stock, and though

it is very likely they really have done so,yet this conclusion rests on deduction andcan hardly hope to establish itself upon abasis of observation And theprimitiveness of the supposed singlestock, which, after all, is the essential part

of the matter, is not only a hypothesis, butone which has not a shadow of foundation,

if by "primitive" he meant "independent ofany other living being." A scientificdefinition, of which an unwarrantablehypothesis forms an essential part, carriesits condemnation within itself; but, evensupposing such a definition were, in form,tenable, the physiologist who shouldattempt to apply it in Nature would soonfind himself involved in great, if notinextricable, difficulties As we have said,

it is indubitable that offspring 'tend' toresemble the parental organism, but it isequally true that the similarity attainednever amounts to identity, either in form or

in structure There is always a certainamount of deviation, not only from theprecise characters of a single parent, butwhen, as in most animals and many plants,the sexes are lodged in distinctindividuals, from an exact mean betweenthe two parents And indeed, on generalprinciples, this slight deviation seems asintelligible as the general similarity, if wereflect how complex the co-operating

"bundles of forces" are, and howimprobable it is that, in any case, theirtrue resultant shall coincide with any meanbetween the more obvious characters ofthe two parents Whatever be its cause,

however, the co-existence of this tendency

to minor variation with the tendency togeneral similarity, is of vast importance inits bearing on the question of the origin ofspecies

As a general rule, the extent to which anoffspring differs from its parent is slightenough; but, occasionally, the amount ofdifference is much more strongly marked,and then the divergent offspring receivesthe name of a Variety Multitudes, of whatthere is every reason to believe are suchvarieties, are known, but the origin of veryfew has been accurately recorded, and ofthese we will select two as moreespecially illustrative of the main features

of variation The first of them is that of the

"Ancon," or "Otter" sheep, of which a

careful account is given by Colonel DavidHumphreys, F.R.S., in a letter to SirJoseph Banks, published in thePhilosophical Transactions for 1813 Itappears that one Seth Wright, theproprietor of a farm on the banks of theCharles River, in Massachusetts,possessed a flock of fifteen ewes and aram of the ordinary kind In the year 1791,one of the ewes presented her owner with

a male lamb, differing, for no assignablereason, from its parents by aproportionally long body and short bandylegs, whence it was unable to emulate itsrelatives in those sportive leaps over theneighbours' fences, in which they were inthe habit of indulging, much to the goodfarmer's vexation

The second case is that detailed by a noless unexceptionable authority thanReaumur, in his 'Art de faire eclore lesPoulets' A Maltese couple, namedKelleia, whose hands and feet wereconstructed upon the ordinary humanmodel, had born to them a son, Gratio,who possessed six perfectly movablefingers on each hand, and six toes, notquite so well formed, on each foot Nocause could be assigned for theappearance of this unusual variety of thehuman species.

Two circumstances are well worthy ofremark in both these cases In each, thevariety appears to have arisen in fullforce, and, as it were, 'per saltum'; a wideand definite difference appearing, at once,

between the Ancon ram and the ordinarysheep; between the six-fingered and six-toed Gratio Kelleia and ordinary men Inneither case is it possible to point out anyobvious reason for the appearance of thevariety Doubtless there were determiningcauses for these as for all otherphenomena; but they do not appear, and

we can be tolerably certain that what areordinarily understood as changes inphysical conditions, as in climate, in food,

or the like, did not take place and hadnothing to do with the matter It was nocase of what is commonly calledadaptation to circumstances; but, to use aconveniently erroneous phrase, thevariations arose spontaneously Thefruitless search after final causes leadstheir pursuers a long way; but even those

hardy teleologists, who are ready to breakthrough all the laws of physics in chase oftheir favourite will-o'-the-wisp, may bepuzzled to discover what purpose could

be attained by the stunted legs of SethWright's ram or the hexadactyle members

of Gratio Kelleia

Varieties then arise we know not why;and it is more than probable that themajority of varieties have arisen in this

"spontaneous" manner, though we are, ofcourse, far from denying that they may betraced, in some cases, to distinct externalinfluences; which are assuredly competent

to alter the character of the tegumentarycovering, to change colour, to increase ordiminish the size of muscles, to modifyconstitution, and, among plants, to give

rise to the metamorphosis of stamens intopetals, and so forth But however they mayhave arisen, what especially interests us atpresent is, to remark that, once inexistence, varieties obey the fundamentallaw of reproduction that like tends toproduce like; and their offspringexemplify it by tending to exhibit the samedeviation from the parental stock asthemselves Indeed, there seems to be, inmany instances, a pre-potent influenceabout a newly-arisen variety which gives

it what one may call an unfair advantageover the normal descendants from thesame stock This is strikingly exemplified

by the case of Gratio Kelleia, whomarried a woman with the ordinarypentadactyle extremities, and had by herfour children, Salvator, George, Andre,

and Marie Of these children Salvator, theeldest boy, had six fingers and six toes,like his father; the second and third, alsoboys, had five fingers and five toes, liketheir mother, though the hands and feet ofGeorge were slightly deformed The last,

a girl, had five fingers and five toes, butthe thumbs were slightly deformed Thevariety thus reproduced itself purely in theeldest, while the normal type reproduceditself purely in the third, and almost purely

in the second and last: so that it wouldseem, at first, as if the normal type weremore powerful than the variety But allthese children grew up and intermarriedwith normal wives and husband, and then,note what took place: Salvator had fourchildren, three of whom exhibited thehexadactyle members of their grandfather

and father, while the youngest had thepentadactyle limbs of the mother andgrandmother; so that here, notwithstanding

a double pentadactyle dilution of theblood, the hexadactyle variety had the best

of it The same pre-potency of the varietywas still more markedly exemplified inthe progeny of two of the other children,Marie and George Marie (whose thumbsonly were deformed) gave birth to a boywith six toes, and three other normallyformed children; but George, who was notquite so pure a pentadactyle, begot, first,two girls, each of whom had six fingersand toes; then a girl with six fingers oneach hand and six toes on the right foot,but only five toes on the left; and lastly, aboy with only five fingers and toes Inthese instances, therefore, the variety, as it

were, leaped over one generation toreproduce itself in full force in the next.Finally, the purely pentadactyle Andrewas the father of many children, not one ofwhom departed from the normal parentaltype.

If a variation which approaches thenature of a monstrosity can strive thusforcibly to reproduce itself, it is notwonderful that less aberrant modificationsshould tend to be preserved even morestrongly; and the history of the Anconsheep is, in this respect, particularlyinstructive With the "'cuteness"characteristic of their nation, theneighbours of the Massachusetts farmerimagined it would be an excellent thing ifall his sheep were imbued with the stay-

at-home tendencies enforced by Natureupon the newly-arrived ram; and theyadvised Wright to kill the old patriarch ofhis fold, and install the Ancon ram in hisplace The result justified their sagaciousanticipations, and coincided very nearlywith what occurred to the progeny ofGratio Kelleia The young lambs werealmost always either pure Ancons, or pureordinary sheep 3 But when sufficientAncon sheep were obtained to interbreedwith one another, it was found that theoffspring was always pure Ancon.Colonel Humphreys, in fact, states that hewas acquainted with only "onequestionable case of a contrary nature."Here, then, is a remarkable and well-established instance, not only of a verydistinct race being established 'per

saltum', but of that race breeding "true" atonce, and showing no mixed forms, evenwhen crossed with another breed.

By taking care to select Ancons of bothsexes, for breeding from, it thus becameeasy to establish an extremely well-marked race; so peculiar that, even whenherded with other sheep, it was noted thatthe Ancons kept together And there isevery reason to believe that the existence

of this breed might have been indefinitelyprotracted; but the introduction of theMerino sheep, which were not only verysuperior to the Ancons in wool and meat,but quite as quiet and orderly, led to thecomplete neglect of the new breed, so that,

in 1813, Colonel Humphreys found itdifficult to obtain the specimen, whose

skeleton was presented to Sir JosephBanks We believe that, for many years,

no remnant of it has existed in the UnitedStates

Gratio Kelleia was not the progenitor

of a race of six-fingered men, as SethWright's ram became a nation of Anconsheep, though the tendency of the variety

to perpetuate itself appears to have beenfully as strong in the one case as in theother And the reason of the difference isnot far to seek Seth Wright took care not

to weaken the Ancon blood by matchinghis Ancon ewes with any but males of thesame variety, while Gratio Kelleia's sonswere too far removed from the patriarchaltimes to intermarry with their sisters; andhis grandchildren seem not to have been