D'Arcy Thompson and the Science of Form Author(s): Stephen Jay Gould Source: New Literary History, Vol. 2, No. 2, Form and Its Alternatives (Winter, 1971), pp. 229258 Published by: The Johns Hopkins University Press Stable URL: http://www.jstor.org/stable/468601 Accessed: 22-04-2015 15:47 UTC REFERENCES Linked references are available on JSTOR for this article: http://www.jstor.org/stable/468601?seq=1&cid=pdf-reference#references_tab_contents You may need to log in to JSTOR to access the linked references. Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at http://www.jstor.org/page/ info/about/policies/terms.jsp JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. The Johns Hopkins University Press is collaborating with JSTOR to digitize, preserve and extend access to New Literary History. http://www.jstor.org This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions D'Arcy Thompsonand theScience of Form Stephen JayGould Our own studyof organicform,which we call by Goethe'sname of Morphology,is but a portionof thatwiderScience of Form whichdeals withthe formsassumedby matterunderall aspectsand conditions,and, in a stillwidersense,withformswhichare theoretically imaginable. Growthand Form,p. 1026 Preface JN 1945, the Public Oratorof Oxfordlauded D'ArcyThompson as unicumdisciplinaeliberalioris exemplar1;in 1969, the Whole EarthCatalog called his majorwork"a paradigmclassic." Few in theircompendium of honors. men can listsuchdiversedistinctions But then,fewmenhave displayedso wide a rangeof talent. D'Arcy WentworthThompson (I86O-I948), Professorof Natural Historyat Dundee and St. Andrews,2translatedAristotle'sHistoria Animalium, wrote glossariesof Greek birds and fishes,compiled statisticsfor the The outstandingexample of a man of liberal education-on the occasion of his i admission to the honorarydegree of Civil Law. Quoted in Ruth D'Arcy Thompson, D'Arcy Wentworth Thompson: The Scholar-Naturalist (London, 1958), P. 238. 2 Of D'Arcy Thompson's life and personalityI shall say little in the limited space available here. See the biographywrittenby his daughter (cited in footnote I) and the best three of many articles written to celebrate Growth and Form: J. T. Bonner, editor's introductionto abridgmentof D'Arcy Thompson, On Growth and Form (Cambridge, 1966), pp. vii-xiv; G. Evelyn Hutchinson, "In Memoriam, D'Arcy WentworthThompson," American Scientist,xxxvi (1948), 577-606; P. B. Medawar, "D'Arcy Thompson and Growth and Form," postscriptto Ruth D'Arcy Thompson's biography of her father,pp. 219-33, and reprintedin The Art of the Soluble (London, 1967), pp. 21-35. As a furthersource of informationand tribute to the syntheticattraction of D'Arcy Thompson's ideas on form,see the books that arose from two recent art exhibitionson organic form: L. L. Whyte, ed., Aspects of Form (London, I951), for the I951 Exhibition at the Instituteof Contemporary Art, London, designed as a tribute to D'Arcy Thompson; and P. C. Ritterbush, The Art of Organic Forms (Washington, 1968), for the 1968 Exhibition at the Museum of Natural Historyin Washington,D. C. This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions 230 NEW LITERARY HISTORY thearticleon pycnogonids3 BoardofScotlandand contributed Fishery to the CambridgeNaturalHistory.4He also wrotea book of one as wellas byengineers thousandpages,revered and architects byartists and biologists-the"paradigmclassic,"On Growthand Form (1917, 2nd edition,1942). To P. B. Medawar it is "beyond comparisonthe in all theannalsof sciencethathavebeen reworkofliterature finest it is "one cordedin theEnglishtongue."5 To G. EvelynHutchinson, of the veryfewbookson a scientific matterwrittenin thiscentury whichwill,onemaybe confident, culture." 6 lastas longas ourtoofragile on organicform;these In it D'ArcyThompsondisplayedhisthoughts in othersand alwaysprofound. are curiousin places,almostvisionary Almostthirtyyearsafterthe secondedition,and morethan half a afterthefirst, century theyhave gainednewimpactin a sciencethat to deal withhisinsights. onlynow has thetechnology I. IneluctableModalityoftheVisible "Extension,figure,number,and motion.. .," wroteJohnLocke, "may calledreal,originalor primary be properly qualities,becausetheyare whether are in thethingsthemselves, or no."'7 Stephen they perceived Daedalus,walkingalongthe Irishsea side,reviewedthe dilemmasof and evenperformed thecrucialexperiment: "Ineluctable epistemology of he the Then was aware of visible... . them bodies before modality of themcoloured.How? By knocking his sconceagainstthem.... Open youreyesnow.I will.One moment.Has all vanishedsince?... See now. There all the timewithoutyou: and evershallbe, world without end."8 3 A small group of marine arthropods that would, I am sure, be considered obscure by all but the veryfew who love (and study) them. 4 D'Arcy Thompson's complete bibliography to I945 will be found in: G. H. Bushnell, "A list of the published writingsof D'Arcy WentworthThompson," in W. E. Le Gros Clark and P. B. Medawar, eds., Essays on Growth and Form presented to D'Arcy Wentworth Thompson (Oxford, 1945), PP. 386-400. The list contains 279 items. This volume is a series of essays presented to D'Arcy Thompson on the occasion of his 6oth year as an active professor. 5 Medawar (see footnote2), p. 232. 6 Hutchinson (see footnote2), p. 579. 7 John Locke, "Some Farther Considerations Concerning our Simple Ideas of Sensation," from Book I of An Essay Concerning Human Understanding (1690). 8 JamesJoyce,Ulysses (New York, 196I), p. 37. This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions D'ARCY THOMPSON AND THE SCIENCE OF FORM 231 Formpervadesthematerialworld.Aristotle was willingto consider formwithoutmatterforprimemoversand demiurges, but notmatter withoutform.9In studyingnatureever since,mostbiologistshave agreedwithNeedhamthat" thecentralproblemofbiologyis theform suited To anyonewhoviewsformas an outdatedconcern, problem."'10 the of world dominated for few a taxonomists only surviving by the a and of recommend book molecular I chemistry energetics biology," thatstandssecondonlyto D'ArcyThompson'sas a 20thcentury paean the to form: J.D. Watson'sThe DoubleHelix. Forthisbookdescribes 12 that to of a "too not a be true," molecularshape pretty pursuit shape ofheredity.Watson'ssucwouldunderlieand explainthephenomena froma concernwithform,froma methodology cess emergeddirectly tothesearchfor ofmodelsinpreference theconstruction thatprescribed He describesa lessonimpartedby Francis a moresubtlechemistry. Crick: "I soonwas taughtthat... thekeyto Linus' [Pauling]success was hisrelianceon thesimplelawsofstructural chemistry. .... The essentialtrick... was to askwhichatomsliketo sitnextto each other. toolswerea setofmoleIn placeofpenciland paper,themainworking children."13 of the cularmodelssuperficially resembling toys preschool thatthey not follow but it does with deal must All biologists form, treatit adequately.In myown fieldof evolutionary biology,I detect insufficient whencomparedwith threeapproachesthatseemespecially ofD'ArcyThompson: theinsights to renderformin suchnon-morphological I. Theoriesthatattempt termsas motion,flow,and energy: Darwin'ssuccessand Lamarck's on specific failureis no simpleconsequenceof theirdiffering positions For to form. their reflects also it Lamarck, approaches opposing points; motionand becomingwere primary;organicmatter,ever in flux, mountedthe scale of being,impelledby "the forcewhichtendsin9 See J. Needham'sanalysisin "BiochemicalAspectsof Form and Growth,"in L. L. Whyte(see footnote 2), pp. 77-86. and Order Mass.,1968), p. 23. Life (Cambridge, Io J.Needham, in I fearthat the messageof molecularbiologyhas oftenbeen mistranslated I thiswayas it descended(or ascendedaccordingto one'sorientation)fromtechnical Americanto theNew YorkTimesand intopopularconjournalsthroughScientific is reladoes not preachthat "everything sciousness.Justas Einsteinianrelativity tive" (ratherthe opposite,in fact), neitherdoes molecularbiologyreplace the or withthe dynamicsof chemicalenergetics conceptof formand spatialstructure the abstractionof "information models"; the greatestachievementof molecular biology,afterall, was theelucidationby Watsonand Crickof thephysicalshape of thisgeneticinformation. moleculethattranscribes DNA, theextraordinary I J.D. Watson,The DoubleHelix (New York,1968). 13 Ibid.,p. 38. This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions 232 NEW LITERARY HISTORY cessantlyto complicateorganization."As Gillispie14writes: "Lato makea scienceout was thelastattempt marck'stheory ofevolution of theinstinct ... thattheworldis fluxand process,and thatscience ofmatter, northecategories ofform, is to study,nottheconfigurations whichis ontologically fundamenbutthemanifestations ofthatactivity tal as bodiesin motionand speciesof beingare not." To Darwin, we sensethisin hisalparadoxicalas it mayseem,formwas primary; oforchids, mostpoeticaladmiration fortheelaborateforms exquisitely to insure insects. 15 designed pollination by Gillispiecontinues:"What [Darwin]did was to treatthatwholerangeofnaturewhichhad been tobecoming, setofobjective as a problemofbeing,an infinite relegated situations back time .... The Darwinian theoryof reaching through evolution turnedtheproblemofbecoming intoa problemofbeingand the eventualmathematization of thatvast area of nature permitted of fromlogosin thewrappings whichuntilDarwinhad beenprotected 16 process." The triumphof Darwinism,however,did not assurean adequate ofform.The analysisofbiologicalformmustemphasizethe treatment of a structure to perform functions conceptof adaptation-thefitness of animalsthat to an organism.Good designis an attribute beneficial ofa Paleyor a Cuvier. It should, intothemetaphysic fitcomfortably of course,have been just as congenialto Darwinism(as it was to forevolution had merely Darwinhimself), substituted naturalselection forGod as the efficient cause of adaptation.Evolutionists and creationists wereequallyhappyto findgood designin nature,theformer theeffects ofnaturalselection, becauseitillustrated thelatterbecauseit of hiscreativeinterference. mainfested God's plan fora worldworthy Yet modernevolutionary form,"to theoryhas tendedto deemphasize dissolve, despiteitsgreatverbalemphasison function, genuineadaptationintothe non-morphological conceptsof gene-pool,genetical'fit17 In etc." ness,'adaptivezones, part,thisis thelegacyof earlyevoluwho choseto avoidthe conceptof design(whichrepresented tionists the old biology,thoughit fitas wellwiththe new) and to use form onlyas a clue to the tracingof lineages.It has led to somecurious 14 C. C. Gillispie, "Lamarck and Darwin in the History of Science," in B. Glass, O. Temkin and W. L. Strauss, Jr.,eds., Forerunnersof Darwin: 1745-1859 (Baltimore, 1959), PP. 268-69. 15 See Origin of Species (6th ed.): account of Criiger's experimentsin chapter 6. Darwin also devoted an entire book to the subject: On the Various Contrivancesby which Britishand Foreign Orchids are Fertilized by Insects (1862). 16 Gillispie, "Lamarck and Darwin," p. 291. I7 M. J. S. Rudwick, "The Inference of Function from Structure in Fossils," BritishYournal forthe Philosophyof Science, xv ( 1964), 39. This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions D'ARCY THOMPSON AND THE SCIENCE OF FORM 233 "the enigmas,mostnotablyto thechargethatSpencer'scatch-phrase, survivalof the fittest," is circularbecausefitness is measuredas the does so define capacityforsurvival.Indeed,the moderngeneticist ofform, butDarwindid not. To him,fitness was a property "fitness"; a measureofgooddesignthatdidnotentailsurvival, a priori.In many anti-Darwinian ofevolution, thefit,in thissense,do notnecestheories sarilysurvive(notionsof racial old-ageor orthogenesis propellinga coursesbeyondthepointof adaptation). Spencer's lineageon straight theprimary of Darwin'ssystem phrase,therefore, expresses prediction and embodiesthetestbywhichit can be comparedwithothertheories and accepted. but do notattemptto ex2. Theoriesthatdeal withformdirectly taxonomists who to it: Among pretend engagein puredescripplain ofthismost thatexaltstheunsullied tion,thereis a mystique objectivity freefromtheinhumbleserviceto Nature,thisdisplayof Her forms, trusionof humanspeculationand thevanityof theory.The ironyof forno human of its attainment, thisattemptlies in the impossibility "Pure" see the can the Ding-an-sich. description, piece-by-piece being is as firmly rootedin theoryas themost of an organism, compendium to theproblemis notonly abstractand mathematical form; approach is hidden,but also thatit is wrong.A standardspecies thatitstheory catalogstheorganismpartby part; thisimplies,in a way description becauseit is inexplicitand even uninthatis subtleand captivating a framework foritsseparatepartsand tended,thatan animalis merely thistheory thatitscomplexity is irreducible.In purelyheuristic terms, is slim;for to reality is sterileand we musthopethatitscorrespondence onceit is statedwe can do littlewithformbutcatalogit in wonder. 3. Theoriesthattryto explainform,but do so incompletely:In fortheregular the i89o's D'ArcyThompsondevelopedan explanation them at cell conHe ascribed to of form spongespicules. adsorption the reflects their tacts; regularform, (Fig. I) merely simplegeometry ofcells.MichaelFoster, ofan aggregate assumedundersurfacetension, was displeased: "I confessI am an eminent evolutionary physiologist, of work .... Does yourresult the line notverymuchattracted wholly by in value of the the spicules?If theformis constant destroy diagnostic This 1 about." form is not matter how the does a group-it brought the approachto formthat characterized statement early epitomizes evolutionary thoughtand offendedD'Arcy Thompson. This is the idea thatformis to be usedonlyas ofmorphology-the "sign"theory are to be analyzedas a guideto thetracingoflineages;thatstructures not as designsformodemexistence;and thatform signsof ancestry, 18 Quoted in Ruth D'Arcy Thompson, p. go. This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions NEWLITERARY HISTORY 234 ... FIo. i. D'Arcy Thompson's illustrationof the regular formof sponge spicules. From his chapter ix, "On concretions,spicules and spicular skeletons." is explainedonceitsantecedents in ontogeny areidentiand phylogeny are of recapitulation, structures fied. Thus,underthetheory juvenile notto deterstudiedto identify theancestral adultthattheyrepresent, minehowtheyfunction in theyounganimal. D'ArcyThompsondid notgainsaytheuseofformto tracelineages;he did decrya morpholowhenit had donethis-forexitsworkcompleted gythatconsidered of Aristotle translator as the understood,19 requiresthe planation, I9 So many heated (and empty) argumentsabout "proper" explanation would be avoided if scientistsonly heeded Aristotle's ancient lesson on the multiplicity of causes (and realized that differentdisciplinesidentifydifferentcauses and then, in their limited perspective,wronglyclaim a full explanation). In what D'Arcy Thompson called Aristotle's"parable" of the house (next paragraph of main text), we must consider the various factors,in the absence of which a particular house could not have been built: the stones that compose it (material cause), the mason who laid them (efficientcause), the blueprintthat he followed (formal cause), and the purpose for which the house was built (final cause). This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions D'ARCY THOMPSON AND THE SCIENCE OF FORM 235 ofmany"causes." We try,forexample,to determine the identification of a well-designed to its final This function cause. structure, identify remainsinsufficient still. In an earlyarticleon theshapesof eggs,he offinalcauses(prevention ofrollingoutofthenest, mentions a variety closepackingwithinthenesttopermit moreeggsin a givenspace) and to comments:"Whatevertruththerebe in theseapparentadaptations we can a that it is existingcircumstances, onlyby veryhastylogic acceptthemas a veracausa or adequateexplanationof thefacts."20 cause as well: "In Aristotle's We muststatetheefficient parable,the houseis therethatmenmaylivein it; butit is also therebecausethe All the while,like buildershave laid one stoneupon another.... and mechanism and are interwoven and woof, warp teleology together, we mustnotcleaveto theone nordespisetheother;fortheirunionis rootedintheverynatureoftotality" (p. 7).21 ofnatureto theidea oforganic anchored view his D'ArcyThompson form(contraz); he triedto explainformby reducingitscomplexity tosimpler thatcouldbe identified as causes(2) ; he recognized elements is multifaceted; thatexplanation thattheidentification onlyof a purincoma a or a ancestor, mechanism, pose, provides pitifully phyletic ofform(3) . pleteanalysis II. D'Arcy Thompson's Theory of Form In the epilogueto Growthand Form,D'Arcy Thompsonstatedhis is ... aim: "to shewthata certainmathematical aspectofmorphology and of Growth to the nayessential, properstudy comprehension helpful, he wrote:"Numericalprecision and Form"(p. o096). In thepreface, affords thebest,perhaps is theverysoulofscience,and itsattainment ofexperiand thecorrectness ofthetruthoftheories theonlycriterion withhis he invokedAuthority ments"(p. 2). In theopeningsentence, and of his the "Of erudition: day generation, chemistry customary Kantdeclaredthatitwas a science,butnotScience-eineWissenschaft, oftruesciencelayin its thatthecriterion abernichtWissenschaft-for This was an old story: forRogerBacon had relationto mathematics. and Leonardoda Vinci calledmathematics portaet clavisscientiarum, 20 "On the Shapes of Eggs, and the Causes whichDeterminethem,"Nature, 1 1. lxxviii (1908), All page numberscited in the text referto the 2nd edition of On Growth and 2 Form (Cambridge, 1942). This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions NEWLITERARY HISTORY 236 had said much the same ...." (p. i-there followsan untranslated Italianfootnote). Yet D'ArcyThompson'smathematics has a curiousring. We find noneofthedifferential thatadorn statistics equationsand mathematical we read,instead,ofthe modernworkin ecologyorpopulation genetics; of space,the tetrakaidekahedron, the Miraldiangle,the partitioning enterequations; logarithmic spiralandthegoldenratio.Numbersrarely For D'ArcyThompsonwas a Greek rather, theyexemplify geometry. with2othcentury mathematician materialand insights.Growthand Formis thesynthesis ofhistwolives: eminentclassicist and eminent AddresstotheClassicalAssociazoologist.As hestatedin a Presidential tion (1929): "Science and the Classics is my theme today; it could hardlybe otherwise.For all I know,and do, and wellnighall I love and carefor(outsideofhomeand friends)lieswithinone ortheother; andthefactthatI havelovedthembothhas coloredall mylife,and enandmultiplied largedmycuriosity myinletstohappiness."22 Those who recognizethe classicalrootsof Growthand FormgenYet Aristotle erallylinkthatworkto Aristotle. represented onlyone of the two classicalinputsto D'ArcyThompson'sscience-and the one oflesserimportance forGrowthand Form. D'ArcyThompsonrevered Aristotle as a descriptive naturalist:"In his exhaustive accumulation and treatment offacts,hismethodis thatoftheobserver, ofthescientificstudent, and is in themaininductive." he identified 23 Moreover, as Aristotle's whatmostcriticsconsiderthetwinstrengths weaknesses of Growthand Form: aesthetic and mathematical style24 skill.25 a classicist had comparedArishimself, D'ArcyThompson'sfather, totle'steachings "to theinvigorating ofsea-bathing, properties openair, wholesome dietand quinine"and the"preaching"of regularexercise, Platoto "opiumor hachish." and thelaterPlato 26 It is to Pythagoras oftheTimaeusthatD'ArcyThompsonoweshisvision;forhe tried,as did BertrandRussell,"to apprehend thePythagorean powerbywhich numberholdssway above the flux."27D'Arcy Thompsonaccepted 22 Quoted in Ruth D'Arcy Thompson, p. 196. 23 "On Aristotleas a Biologist,"Nature, xci ( 913), 204. 24 Ibid., p. 2o2: "Wise and learned as Aristotlewas, he was neither artist nor poet. His styleseldom rises ... above its level, didactic plane." 25 Ibid., p. 20o: "I have my doubts as to his mathematics. In spite of certain formidible passages in the 'Ethics,' in spite even of his treatise, De Lineis Insecabilibus, I am tempted to suspect that he sometimespassed shylybeneath the superscriptionover Plato's door." According to legend, the inscription over the door of the Academy read: "Let no one enter here who is ignorant of geometry." 26 Quoted in Hutchinson (see footnote2), p. 578. 27 Bertrand Russell, "What I have Lived For," in The Autobiographyof Bertrand Russell, Vol. I, z872-z914 (Boston, 1967), pp. 3-4. This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions D'ARCY THOMPSON AND THE SCIENCE OF FORM 237 neitherPythagoras' doctrinethat"thingsare numbers,"28 nor Plato's the from bodies visionofa realmofidealnumbers existing physical apart But he did thatare but theirfleeting and imperfect representation. sharetheirgeneralattitudes:thatsolutionsto the world'smysteries shouldbe soughtin "the geometrical 29; thatsimaspectof number" and truthwouldbe foundconsymmetry, harmony plicity, regularity, joined"; thattheworldof "science"couldbe approachedand coma book on the prehendedby poeticvision.As he wrotein reviewing or or "The Pythagoreans: Pythagorean, Platonic, Jewishconceptof Numberis a hard sayingto the unpoetic,non-mystical modemand Westernworld; and manya way is foundto show that Plato and meantsomething afterall. Butto Pythagoras prosyand commonplace of someitis stillas plainas everthatNumberis theclueto thegreatest what whether of and that we call or sound beauty, mysteries, earthly In Growthand Form,Plato form,is but its resultant expression."31 28 In the Metaphysics,Aristotlewrote of the Pythagoreans: "They assumed that the elementsof numberswere the elementsof all things,and that the whole heavens were harmonyand number." This view seems so arcane in today's context that we tend to see in it the most abstract of mysteries. In an Ionian setting,it makes for respectablescience as well. R. M. McInerny, A History of WesternPhilosophy: Vol. I, From theBeginnings of Philosophyto Plotinus(NotreDame, 1968), p. 45, has shown how the Greek's very "manner of depicting numbers leads to speaking of types of numbersprogressingin termsof dimensions." The lonians had no written numerals; the Pythagoreans, in fact, represented numbers with sets of pebbles arranged in geometric form. Bodies were then generated from points (pebbles) representingunits: the number I produced a point, 2 a line, 3 a triangle,and 4 a pyramid; moreover, the Pythagoreans had no notion of a continuum and viewed lines as series of discrete points (- units, = numbers). It is no distant extrapolation from this to a notion that the "elements of number are the elements of all Since their way of depicting numbers produced plane and solid things. ... figures,bodies and even physical bodies, were taken by the Pythagoreans to be composed of units and, consequently, these bodies are numbers" (McInerny, p. 47). D'Arcy Thompson, of course denied that numbersare the material cause of physical objects; he did, however, view number as a formal cause: numbers generate the symmetricaland regular shapes that organic formsassume under the influenceof physical forces. 29 D'Arcy Thompson's words in speaking of Pythagorean mathematics: "The Hellenic Element in the Development of Science," Nature, cxxiii (1929), 732. 30o Discussing the honeycomb in Growth and Form (p. 529), D'Arcy Thompson speaks of "the two principlesof simplicityand mathematical beauty as ... sure and sufficientguides." And later, in the epilogue (p. 1o97): "the perfectionof mathematical beauty is such . . . that whatsoever is most beautiful and regular is also found to be most usefuland excellent." 31 "The School of Pythagoras," Nature, xcviii (x9I6), 166. The very next sentence reads: "It was in the very spirit of Pythagoreanmysticismthat that great naturalist,Henri Fabre, wrote his great ode to number." And it was with a quotation fromthat "great ode" that D'Arcy Thompson chose to end Growth and Form, calling Fabre "that old man eloquent, that wise student and pupil of the ant and of imthe bee . . . who in his all but saecular life had tasted of the firstfruits This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions NEW LITERARY HISTORY 238 and Pythagoras dreamers"(p. 2). arelinkedas "thosegreatphilosophic of the heavenlyhostmustbe determined "Not onlythe movements and elucidatedby mathematics, else but whatsoever by observations can be expressed by numberand definedby naturallaw. This is the and themessageofGreekwisdomto teachingofPlatoand Pythagoras, mankind" (p. 1097). Growthand Formis not a textin anachronistic Greekbiology.It modemtheories(Darwinismin parusesclassicalconceptsto criticize withtheproblems ofengineerticular),and itshowsa manas familiar in as the of with ing bridgedesign tetractys Pythagoras.It expresses the tensionsand conflicts thatmustinherein any philosophy comfrom such sources. Of two are these tensions, pounded disparate parin Growthand Form. I) His viewof Plato and ticularly important and deduction)versusAristotle generality Pythagoras(mathematics, and His Greek commitment to a pureand (description induction).2) of form abstract versus Baconian idea that his understanding knowledge is power,as expressed lovefora good designbecause bytheengineer's itworks. showedin hisperceptive As Hutchinson 32D'ArcyThompson's essay, threethemes: an old idea to whichhe theoryof formencompasses broughtnew lightand grace,a theoryon the productionof form and a mathematical methodforrepresenting thecauses growth through in shapeamongrelatedorganisms. ofdifferences are well designedis amongthe oldestideas of i. That organisms Galileoand Borelli,33 biology.WhatD'ArcyThompsondid,following was to conductthisobservation awayfrompassivewonderat nature's marvelstowardthe analytictechniquesof physics, mathematics and When is the this of form becomes a science: done, study engineering. can be madeandtested;actualforms canbe comparedwith predictions the ideal configurations that engineersprescribe;the superiority of one formoveranothercan be assessedand evenmeasured. mortality... in whose plainest words is a sound as of bees' industriousmurmur;and who, being of the same blood and marrow with Plato and Pythagoras, saw in Number le comment et le pourquoi des choses, and found in it la clef de voiite de l'Univers" (p. og97). I thinkwe may include D'Arcy Thompson among the "some" to whom "it is still as plain as ever. ... 32 Hutchinson (see footnote2). 33 Galileo's major discussionis in the "Dialogue of the Second Day" in Dialogues Concerning Two New Sciences (1638), trans.H. Crew and A. de Salvio (New York, 1914). Here he displays the mechanical consequences of size increase, demonstrates the impossibilityof giants and explains why large animals must have relatively thickerlegs than smaller relatives. Borelli's treatise,De Motu Animalium, was published in 1685. This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions D'ARCY THOMPSON AND THE SCIENCE OF FORM 239 of thistheme,the pages of Growthand Form As one illustration thatorganicshapesconform aboundwithexamplesdemonstrating to at theirscale. The pervasive thephysical forcesprevailing ofsize effect upon formis a simpleconsequenceof physicallaws and geometric arguments.As an animal (or any object) grows,its volumewillincreaseas thecubeofitslengthwhileitssurface, ifit maintains thesame as the the the the increases larger animal, greater only shape, square; the ratioof itsvolumeto itssurface.Thus, a largeanimallivesin a thatworkuponitsvolume worldruledbyforces, gravitation, primarily is littleby gravity;the A smaller animal influenced its mass). (i.e. forcesthatactuponitssurfaceholdswaybecausethatsurfaceis so large affects.Stillotherforces, therandom relativeto themassthatgravity come into for motion the of Brownian shocks playat bacterial example, ofthemost of some This influence size dimensions. explains physical 4 of can walk obvious statements: whyanyfly up a wall,but confusing onlyJesuscould walk on water35;why elephantshave thickerlegs thangazelles36;and whythegiantantsof Themreallycouldn'thave ant reachedtheLos Angelessewers. 37 Kirbyand Spence,extrapolating of a such and the size to calculating prodigious powers power elephant lest the for His in wisdom God thanked leviathan, weakening elephant, oftheworld"(quotedon p. 36). it shouldcause"theearlydesolation D'ArcyThompsonshowedthatifGod had had anyhandin thematter, 34 The differencesbetween life in such a world and ours are brilliantlystated in George Gamow's classic Mr. Tomkins in Wonderland (Cambridge, I94o). Wonderland is a world in which quantum and relativityeffectsoccur at our customarysizes and speeds. 35 The downward force of gravitypulls animals fromwalls and through the surface-filmof a pond; surfacetensionprovides adhesion both to wall and pond surface. Small animals have such a high ratio of surface to volume that the force of surface tensionoutstipsthat of gravity. 36 The strengthof a leg bone is a functionof its cross sectional area; it will increase as the square of length if shape remains constant with increase in size. Yet, the weight that the legs must support increases in proportionto volume, as the cube of length. A series of animals differingin size but not in shape will become progressivelyweaker at larger sizes. In nature, large animals overcome this potential problem by having relativelythick legs with a large cross-sectionalarea; in addition, legs tend to thicken disproportionatelyduring growth. This type of growth-in which shape changes to meet the physical demands of increase in sizeis called "allometric." Julian Huxley pioneered the quantitative study of allometric growth in the Ig92's. See S. J. Gould, "Allometry and Size in Ontogeny and Phylogeny,"Biological Reviews, xli (1966), 587-64o. 37 The ability to stay aloft depends upon wing surface area, but body weight increases as the cube of length. This is the classic problem of "wing loading" in aeronautics; though Hollywood knows little of it, Pliny understood the issue when he wrote in the Historia Naturalis that "the heavier birds can flyonly after taking a run, or else by commencing their flightfroman elevated spot." At their size, the giant ants could not even have taken off from their nest near Alamagordo. In This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions NEW LITERARY HISTORY 240 he had workedin rathermundane fashionthroughthe physicallaws of size.38 Following the general introduction,D'Arcy Thompson began his workwith the eloquent chapter"On Magnitude"-a testimonyto the significanceof size and its physicalconsequences. The chapter ends thus (p. 77) : Life has a rangeof magnitudenarrowindeed comparedto that with whichphysicalsciencedeals; but it is wide enoughto includethreesuch discrepantconditionsas thosein whicha man, an insect,and a bacillus have theirbeingand play theirseveralroles. Man is ruledby gravitation, findsthe surfaceof a pool a and restson motherearth. A water-beetle or an indispensable matterof lifeand death,a perilousentanglement support. In a thirdworld,wherethe bacilluslives,gravitationis forgotten, of the liquid, the resistancedefinedby Stokes'law, the and the viscosity molecularshocksof the Brownianmovement,doubtlessalso the electric and chargesof the ionizedmedium,make up the physicalenvironment on theorganism.The predomihave theirpotentand immediateinfluence nantfactorsare no longerthoseof our scale; we have cometo theedge of and whereall ourpreconceptions a worldofwhichwe have no experience, mustbe recast. 2. The relationshipof size and shape linksthe firstthemeto the second-that physicalforcesexert a direct and immediateinfluencein shapingorganismsas theygrow. This is the guidingconceptof Growth and Form; all but threeor four of its seventeenchaptersare devoted betweenorganicformsand the shapes to thecitationofcorrespondences thatphysicalforcesproducein actingupon non-livingmaterialof similar size, density,viscosity,and rigidity.From these correspondences, D'Arcy Thompson inferredthat organic formshad been fashionedin the same way--by the directaction of physicalforces. fact, they couldn't even have breathed; the tracheae (respiratoryorgans) of insects are invaginations of the external body surface; they must increase in constant proportion to the body weight that they service. For surface to grow as fast as weight, shape must change: the surface must become more elaborate (by increased folding or invagination). There is a limit to this elaboration, lest there be no room forinternal organs. Large animals have avoided this dilemma by evolving separate internal organs (lungs) to harbor a vast amount of surface for respiration. Horror movies are notoriousforthe limited imagination that makes giant insectsact as only normal ones could. The most incredible thing about the Incredible Shrinking Man is that, at three inches, he continues to operate as a gravity-pronesixfooter. 38 Strengthis primarilya functionof the cross-sectionalareas of muscles. Since elephants have smaller areas relative to their weight than small animals, they cannot match the featsof insectswhen these are measured by the inappropriatecriterion of weight liftedvs. body weight. That insects can drag an object many times their own weight is no testimonyto any superior design or prodigious will, but merely a functionof theirsmall size. This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions D'ARCY THOMPSON AND THE SCIENCE OF FORM 24I Many criticshave failedto graspthisview of actionofphysicalforces; theydismissGrowthand Form as a book filledwith curious and ingenious analogies that describesome aspects of formbut explain nothing. To D'Arcy Thompson,however,a correspondencebetweenorthat ganic and inorganicis morethan an analogy; it is a demonstration two objectsprobablyhave the same efficient cause (p. Io) : The wavesof thesea, the littlerippleson theshore,the sweepingcurve of thesandybay betweentheheadlands,theoutlineof thehills,theshape of the clouds,all theseare so manyriddlesof form,so manyproblemsof and all of them the physicistcan more or less easilyread morphology, and adequately solve: solvingthem by referenceto their antecedent phenomena,in the materialsystemof mechanicalforcesto which they themas beingdue .... Nor is it otherbelong,and to whichwe interpret wise withthe materialformsof livingthings.Cell and tissue,shell and bone,leaf and flower,are so manyportionsof matter,and it is in obedience to thelaws of physicsthattheirparticleshave been moved,moulded and conformed. D'Arcy Thompson's analysisbegins at small sizes, in the realm of surface forces. He compares protozoans with Plateau's surfaces of revolution (surfaces of minimal area radially symmetricalabout an axis), and infersfromthe correspondence(Fig. 2) that surfacetension shapes the simple, single-celledanimal. As a liquid cylinderis stretched beyond the limits of stability, it breaks up into "a series of equal and regularlyinterspacedbeads, oftenwith littlebeads regularly interspacedbetweenthelargerones" (p. 386). D'Arcy Thompson finds thesesame beads in the "dew-drops"of a spider'sweb and providesa than that of mechanical explanationfar more simple and satisfactory earliernaturalists(p. 387) : The same phenomenonis repeatedon a grosserscale when the web is bespangledwithdew, and its threadsbestrungwith pearls innumerable. formed theseregularlyarrangedand beautifully To the oldernaturalists, of wonderment. web were a source on the frequent spider's globules Blackwall,countingsometwentyglobulesin a tenthof an inch,calculated web shouldcompriseabout I20,ooo globules; thata largegarden-spider's the net was spun and finishedin about fortyminutes,and Blackwallwas filled with admiration of the skill and quickness with which the theselittlebeads. And no wonder,foraccordingto spidermanufactured theabove estimatetheyhad to be made at therateof about50 per second. At largersizes,gravitycomes into play. In the medusae of coelenterates, "jellyfish"and their relatives,D'Arcy Thompson was "able to discover various actual phases of the splash or drop [Fig 3] .... It is hard indeed to say how much or littleall these analogies imply. But theyindicate,at the veryleast,how certainsimpleorganicformsmight This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions 242 NEW LITERARY HISTORY FIG. 2. Comparison between one of Plateau's surfaces of revolution (left-unduloid with positiveand negative curvature) and "the flagellate'monad' Distigma proteus." From chapter v, "The formsof cells." be naturallyassumed by one fluidmass withinanotherwhen gravity, surfacetensionand fluid frictionplay theirpart" (p. 397). At still largersizes,surfacetensionbecomes so negligiblethat rigidhard parts are needed to maintainshape, lest gravitymake a world of pancakes. In the internaltrabeculaeof vertebratebones D'Arcy Thompson found patternsthat mirrorthe stressesimposed upon them by the body's weight: A greatengineer. . happened (in the year 1866) to come into his wheretheanatomistwas contemplating colleagueMeyer'sdissecting-room, the sectionof a bone. The engineer,who had been busydesigninga new This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions D'ARCY THOMPSON AND THE SCIENCE OF FORM 243 FIG. 3. Comparisonbetweena fallingdropproducedby fuseloil in paraffin (left) and the medusoid"jellyfish" Syncoryme (right). Fromchapterv, "The formsof cells." and powerfulcrane,saw in a momentthatthe arrangement of the bony trabeculaewas nothingmorenor lessthana diagramof thelinesof stress, or directions of tensionand compression, in theloaded structure:in short, the bone in preciselythe mannerand dithat Naturewas strengthening rectionin whichstrength was required;and he is said to have criedout, "That's mycrane" (pp. 976-977and Fig. 4 of thiswork). From thisobservationof good design,D'Arcy Thompsonmade his usual inferenceto an efficient cause (pp. 984-985): thatour bone is notonlya livingbut a highWe mustalwaysremember ly plasticstructure;the littletrabeculaeare constantly beingformedand This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions NEW LITERARYHISTORY 244 FIG. inthebonytrabeculae crane(left)andas reflected inMeyer's 4. Linesofforce of the human femur (right). From chapter xvi, "On formand mechanical efficiency." deformed,demolishedand formedanew. Here, foronce, it is safe to say that 'heredity'need not and cannotbe invokedto accountfor the conand arrangement of the trabeculae: for we can see themat figuration of life time in the any making,underthedirectactionand controlof the forcesto whichthe systemis exposed ... Herein thenlies,so far as we can discernit, a greatpart at least of the physicalcausationof what at firstsightstrikesus as a purelyfunctionaladaptation: as a phenomenon, in otherwords,whosephysicalcause is as obscureas itsfinalcause or end is apparently manifest. For sheeringenuity,nothingin Growthand Form matchesD'Arcy Thompson's famous,and likelycorrect,explanationforthe narwhal's horn (actually a tooth). This horn may project eight or nine feet beyond the creature'shead; "it never curvesnor bends, but grows as straightas straightcan be" (p. 907); windingabout thisstraightaxis is a screwof severallow-pitchedthreads (Fig. 5); in rare cases, when two hornsare formed,the threadsrun the same way in each: theyare situationforbilaterallysymmetrinot mirrorimages (an extraordinary cal animals). D'Arcy Thompson then notes that screw-threadsare made by combiningforwardand rotatorymotion.Now the propulsion This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions D'ARCY THOMPSON AND THE SCIENCE OF FORM 245 threads. 5. Below: narwhalshowinghornwithstraightaxis and low-pitched FIGo. Above: skullof rare two-horned narwhal;threadsrun in the same directionon bothhorns. This interesting is fromthe 1826 editionof the Compte illustration de Lac6pede'sHistoirenaturelledes cetace'es(originallypublishedin I804 as one of the completing volumesof Buffon'sHistoirenaturelle).Lac6pede, a colleague of Cuvierand Lamarck,wrotethe last volumesof Buffon'smonumental work. ofclosely-related at orginating dolphinscontainsa rotatory component thetail. To thiscomponent, more theflexible actively bodyresponds thanthehornwhichis bothrigidand locatedfarfromthedrivingimis formed becausethenarpulseofthetail. The horn'shelix,therefore, as it swims forward rotates aboutitsown whal, duringgrowth, slowly horn! out 3. The lastchapterofGrowthand Formseems,at first, curiously ofplacein a deductive work.In it D'ArcyThompsonimposesa netof coordinates seriesof rectangular upon variousanimalsand generates relatedspeciesby subjectingthatnetto simpledeformations (Fig. 6 fora set of crab carapaces). Some have seen thisas an exercisein othersas a game,a scherzoto a bookthatnever empiricaldescription, receiveditsfinalmovement. Butit is thefinaleto a coherent work.For his criticshave misseda centralpoint: thatD'Arcy Thompson was in- in the deformed terested in the animalthatit gennet,notprimarily erated.He sawthatnetas a diagramofforces;and justas thetrabecufemurreflected theforcesresponsible fortheirdepolae ofthestressed sition,so would the deformednet depict the forcesthat could trans- formone animalto another.Sincetheseforcesmightproducea form thedeformed netis no mereframework fordescription; it may directly, be a displayofefficient causes. If "diverseand dissimilar fishescan be referred as a wholeto identicalfunctions ofverydifferent co-ordinate thisfactwillofitselfconstitute a proofthatvariationhas prosystems, ceeded on definiteand orderlylines,that a comprehensive 'law of This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions NEW LITERARY HISTORY 246 \(a ) /1( d -mu (f) (ci) of a coordinatenet FIG.6. Carapacesof variouscrabsdisplayedas transformations imposed upon Geryon (a). From chapter xvii, "On the theoryof transformations." initsintegrity, haspervaded thewholestructure andthatsome growth' moreorlesssimple andrecognizable hasbeenin conofforces system trol"(p. 1037). The method oftransformed coordinates is D'ArcyThompson's prorender forcomplex structures. visional mathematics Thoughhe might a simplephysical a cellorevena jellyfish law,he reflecting byforces couldnotbe encompassed so easily. vertebrate knewthata complex mustbe soughtforthe Yethe feltthatmathematical representation the as even when laws well, physical behindthatrepresentacomplex oneform andevenifthismeantaccepting tioncouldnotbe specified, thesimplification andcausalinsight ofmatheas givenandachieving forms.Thus,as Hutchinson ofrelated maticsonlyforthegeneration "whatmaybe calledbyanalogy constructed wrote, D'ArcyThompson a floating ofthearchaeologists, mathematwiththefloating chronology forthetimebeingto physical unanchored icsformorphology, science, onitsownlevel." butcapableofvalidgeneralization This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions D'ARCY THOMPSON AND THE SCIENCE OF FORM 247 The studyof formmaybe descriptive merely,or it maybecomeanalytical. We beginbydescribing theshape of an objectin thesimplewordsof commonspeech: we end by definingit in the preciselanguageof matheof a 'form'has a qualityof prematics... The mathematicaldefinition it is cisionwhichwas quitelackingin ourearlierstageof meredescription; or and or in briefer these words in a few words still symbols, expressed symbolsare so pregnantwithmeaningthat thoughtitselfis economized; we are broughtbymeansof it in touchwithGalileo'saphorism(as old as as old perhapsas thewisdomof theEgyptians) Plato,as old as Pythagoras, that'theBook ofNatureis writtenin charactersof Geometry'(p. I026). III. D'Arcy Thompson and his Critics ofGrowthand Formarenumerous.Theirmajorobjections The critics tothreecategories. canbe condensed of was a relicof pasttimesand a perpetrator D'Arcy Thompson I. here: theirinadequatescience. I detectthreeseparatearguments so pompousin itsVictorianmeter, is so overblown, i) His writing cannot thatharriedprofessionals so ostentatious in itsGreekallusions, I do deem of time. not the with essentials its economy requisite grasp comment. of thisbrandofphilistinism worthy approachbelongsto an earliernatural ii) His non-experimental modem not to science;he nevermanipulatednaturein conhistory, what nature but merelydescribedand interpreted trolledsituations, and its roots are with criticism is serious but This justified, presented. For with Linnaeus. not Aristotle, D'ArcyThompson'sinadequacyis 39limitation and decisive" citedas the"fundamental whatSambursky the AncientGreeks of Greekscience: "With veryfew exceptions, exa periodof 8o00yearsmade no attemptat systematic throughout perimentation. . . The consequence was that inductionwas limited maof such experimental and collection observation to thesystematic inducSuch of natural the terialas was offered study phenomena. by in termsof the conceptionof modem tion was naturallyprimitive with science.""4But ifD'ArcyThompsondid notprovidehisinsights he And are not falsified of experiment theverification thereby. they of Greek secondlimitation to Sambursky's did not,at least,subscribe science: "It doesnotaim at theconquestand controlofnature,butis intellectual motivated .... Forthisreasontechnology curiosity bypurely 39 S. Sambursky,The Physical World of the Greeks (New York, 1956), p. 2. 40 Ibid., pp. 2-3. This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions 248 NEW LITERARY HISTORY findsno placein it; and ifsuffers fromthelackofthatsynthesis ofpure of modem knowledgeand practicalapplicationwhichis thestrength science."41 iii) He gave scantnoticeto modemworkthatvied withhis basic in the inpremisesand evenneglectedto updatematerialcontested terimbetweeneditions.The latterchargeis trueonlyin part. In the 1917 edition(pp. 48-49), forexample,he speakswell of Arrhenius' notionthattheminutest fantastic oforganisms mightescapetheearth's on the electrical force of the Aurora,thenceto be propelled atmosphere the radiant of "like Uriel by energy light, glidingon a sunbeam"(p. 49 of 1917 ed.), to Jupiterin 80 days and to Alpha Centauriin 3,000 ourlifethroughout theuniverse(or to seek years-thusto disseminate theoriginofoursin dispersion fromotherworlds). In 1942,thisfinale to "On Magnitude"was quietlydroppedin favorof the statement quotedon page 240. Butit couldbe excisedbecauseitsimplausibility did notthreatenany premiseof D'ArcyThompson'ssystem:it had servedas a dubiousillustration ofan incontestable truth.42 merely D'Arcy Thompson'sstand was this: he did not alter his basic statements whensomeonechallengedtheirapplicationto particular cases.Afterall, a good theoryis thebestguideforseparating correct fromincorrect"facts"-especiallyin naturalhistorywhere"pure" data are oftenthe passiveand subjectiveobservations of men subtly withunacknowledged a prioris.Whenconfronted withconprejudiced evidence,D'ArcyThompsontrustedhistheoryand hisaestradictory in science,thisis a dangerous theticvision. 43 As a strategy gamble,one thatcan be recommended onlyforthe great. The winnerbecomesa thelosera blinddogmatist. genius, prophetic The viewof D'ArcyThompsonas a relicwillbe embracedor disof thehistory of science.In misseddependingupon one'sconception of inexorableprogress-rendered the Comptianperspective by many as a marchto truthmediatedbythecontinuing scientists accumulation to theAncients, of facts-D'ArcyThompson'shearkening his oppositionto modernfactsin conflict withGreekTruths,mustbe decried. ofsciencehaveanymessageforthepracticing Butifhistorians scientist, withtheelusivequalitiesdeit is thatgreatmenfashiongreattheories and "genius": a sense(oftenaesthetic)thatsomenoting"creativity" Ibid., p. 3. 42 That the smallest organisms are subject to forces (here electricityand the "radiant pressure"of light) that do not affectus. 43 For an account of the positive role of aesthetic convictionsin major scientific discoveries see: E. A. Burtt, The Metaphysical Foundations of Modern Science (New York, 1932). 41 This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions D'ARCY THOMPSON AND THE SCIENCE OF FORM 249 thingis amisswithold ideas,an abilityto bringnewwaysof thinking to an old problem, fortherelative and an "intuitive" feeling importance and reliability And nihilsub sole novum of conflicting information. or no,newwaysare oftenforgotten old ways. 2. D'ArcyThompsonwas a stubborn opponentofmodernideas on tonatural evolution.ManyhavetakenD'ArcyThompson's antagonism obsolescence.In fact, selectionas yetanothersignofhiscantankerous buta specific hisobjections reflect no generalstandagainstmodernity, conflict betweenhisvisionand Darwin's.Seenin thislight,hisopposior so we tionis bothintelligible and judicious.Yet it is also incorrect, implication(but judge today--andherehisvisionfailsin itsstrictest He had threemajorobwe shallsee,in a reinterpretation). triumphs, 4 the last two subjections to Darwinism: the firstmethodological, stantive. was "an endless i) To mostDarwiniansof his time,morphology of thingslivingand the pedigrees searchaftertheblood-relationships of thingsdead and gone" (p. 3). D'Arcy Thompson,as we have alreadyseen (p. 5), decriedthislimitedview thatsoughtonlyfinal he wrotethatwe causesor antecedent states.Of complexorganisms, related and fitted to the as mustboth"lookuponthecoordinated parts of thewholeand as relatedto or resulting end or function fromthe offorces towhichthewhole in theentire system physicalcausesinherent it has comeintobeing" had beenexposed,and underwhoseinfluence (p. io2o; myemphasis). D'ArcyThompsonmusthave enjoyedthe satireupon evoludialogueofKing Lear and the Fool as a prophetic whowouldconsideronlyfinalcauses,and trivialonesat that: tionists Fool: Cansttellhowan oyster makeshisshell? Lear: No. Fool: NorI neither:butI cantellwhya snailhasa house. Lear: Why? Fool: Why,toput'sheadin. D'ArcyThompson geometry, organicformto abstract ii) In relating of of realm notion a real Platonic the form;thisrealm pure approached ofitsformsamong limitsfortheimperfect wouldspecify representation oneinanimals.If mathematical shapescannotbe transformed earthly 44 I speak here only of the objections that arose from his personal theory of form. He also shared many of the common doubts of his contemporariesespecially their reluctance to grant natural selection a creative role: for if selection were only the headsman for the unfit,what created the fit; and if this creation be by "random" mutation, how can exquisite adaptation arise from "chance." The achievements of population genetics in the 193o's resolved these dilemmas by showing that very small selective pressurescould be effectivein superintendingthe gradual fixationof favorable small mutations in natural populations. This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions 250 NEW LITERARY HISTORY to the otherthroughinsensiblegradations,neithercan major discontinuitiesin organicformbe bridgedby theimperceptiblechain of intermediates that Darwinian theoryrequires. Thus, D'Arcy Thompson held that major transitions in evolutionoftenoccur suddenly,by some formof "macromutation."45 An algebraiccurvehas itsfundamental whichdefinesthefamiformula, a helicoid ly to whichit belongs.... We neverthinkof "transforming" intoan ellipsoid,or a circleintoa frequency-curve. So it is withtheforms an invertebrate into a vertebrate, of animals. We cannot transform nor a coelenterateinto a worm,46by any simpleand legitimatedeformation. . . . Natureproceedsfromone typeto another... and thesetypesvary and are definedbyphysico-mathematiaccordingto theirown parameters, chosen cal conditionsof possibility.Cuvier's"types"maynot be perfectly nor numerousenough,but typestheyare; and to seekforstepping-stones across the gaps between is to seek in vain, forever (pp. 1094-1095). iii) D'Arcy Thompson's belief in the direct molding of form by physicalforcesled him to distrusta primaryguide to the tracingof lineages-that degree of similarityis a rough measure of evolutionary affinity(recency of common ancestry). It is somethingof a trade secretthatmostof our evolutionarytreesare based not upon the direct evidence of fossils,but upon inferencesthat equate reasonable series of modem formswith actual affiliationin time. But if the formsof theseseriesare fashioneddirectly,the sequence reflectsno history,but only a gradationof physicalinfluencesobeyingtimelesslaws. Of the single-celledForaminiferahe wrote (pp. 869-870): While we can trace in the most completeand beautifulmannerthe passageof one formintoanotheramongtheselittleshells... thequestion staresus in thefacewhetherthisbe an 'evolution'whichwe have anyright to correlatewithhistorictime. The mathematiciancan traceone conic sectionintoanotherand 'evolve'forexample,throughinnumerable graded in variousforms,was the major evolutionary challenge 45 "Macromutationism," of de Vries (circa I9oo) well into to Darwinismfromthe "Mutationstheorie" of the 1940's and 1950's. The inviabilityof major mutations,the difficulty and the spreadingthemthroughentirepopulationsaftertheyarise in individuals, that small mutationsprovideenoughgeneticvariabilityforevoludemonstration tion have led to the virtualdemiseof thisconcept. D'Arcy Thompson'sreasons foracceptingit wereunique. today,we would not disputethis 46 And thoughwe rejectmacromutationism of complexadult structures.Most specificclaim as it relatesto transformations of their wouldtryto linkthesemajor groupsthroughtransformations evolutionists simpler,larvalforms.Thoughno one (to myknowledge)has evertriedto transchorand primitive forman adult sea urchinto a man, the larvaeof echinoderms datesare verysimilar.The mostpopulartheoryofvertebrate originswouldseekto to larval evolution link the two groupsat thispoint. AlisterHardy has referred as an "escapefromspecialization." This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions D' ARCY THOMPSON AND THE SCIENCE OF FORM 25I ellipses,the circle fromthe straightline: which tracingof continuous stepsis a true'evolution,'thoughtimehas no parttherein.It was afterthis fashionthatHegel, and for thatmatterAristotlehimself,was an evolutionist-towhomevolutionwas a mentalconcept,involvingorderand continuityin thoughtbut not an actual sequenceof eventsin time. Such a conceptionof evolutionis not easyforthemodernbiologistto grasp,and it is harderstillto appreciate. For these simple forms,subject by their small size to surficialand molecular forces,D'Arcy Thompson may well be right. At least his suggestionhas the "audacityof imagination"thatJohnDewey foundin "every great advance in science"; at least it mightfree the students of these animals fromautomatic allegiance to theoriesdeveloped for vertebrates(and notwhollycorrecteven forthem). However,when he applies it to large and complex forms,I begin to doubt its propriety while continuingto admire its sheer ingenuity. Molluscan shells,for example, are spread neitherevenlynor randomlyacross the range of formpotentiallyavailable to them: certainshapes tend to occur again and again. To a modern evolutionist,these recurrentshapes are selected because they are functionallysuperiorto rare or non-existent ones; to D'Arcy Thompson,theyare simplythe shapes that controlling physicalforcesproducemosteasily(p. 849): It is hard indeed (to mymind) to see in such a case as thiswhereNaentersin, or to admitthatit has had any share turalSelectionnecessarily in theproductionofthesevariedconformations. whatsoever Unlessindeed we use thetermNaturalSelectionin a senseso wide as to depriveit of any and so recognizeas a sortofnaturalselection purelybiologicalsignificance; to differentiate betweenthe likelyand whatsoevernexusof causes suffices theeasyand thehard: and leads thescarceand thefrequent, theunlikely, one formof cloud,one chemicalcompound,to be S.. one typeof crystal, of frequentoccurrenceand anotherto be rare. 3. D'Arcy Thompson's centralidea-that formis fashionedby the directaction of physicalforcesoperatingduringgrowth-is applicable to very few of the cases he cites. We must firstunderstandD'Arcy Thompson's own limitsupon his theory. He did not deny "a principle beof heredity"(p. 1023); he did not attemptto ascribe differences tween rhinocerosesand watermelonsto the action of physicalforces. "My sole purpose," he wrote (p. I4-my italics), "is to correlate with mathematicalstatementand physicallaw certainof the simpler outwardphenomenaof organicgrowthand structureor form." Some This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions NEW LITERARY HISTORY 252 of thesecorrelationsare surelycorrect,47 but others,includingthe fundamental comparisonof protozoanswith Plateau's figuresof surface tension,48are almostas surelywrong. This substantialcriticismwould seem to discreditGrowthand Form, relegatingit to the domain of antiquarians ratherthan to historians (not to mentionpracticingscientists). In fact,it providesthe impetus for a reinterpretation that explains the book's continuinginfluence scientific a among communitythatalmostmatches,in itsregardforpast the work, journalist'smaxim: "yesterday'spaper wraps today's garbage."49 D'Arcy Thompson identifiedhundredsof correspondencesbetween physicallaws and organic forms. If his own theorywill not explain them,thenanothermustbe sought. And thatother,ironicallyenough, is natural selection. D'Arcy Thompson claimed a directinfluencefor physical forces; in fact, these forcesoperate indirectlyby specifying the formsthat provideoptimal adaptation for animals subject to their influence. "Equilibrium figures are common in organic nature," Hutchinsonwrites,"because any organismnot exhibitingthem would have to be elaboratelyprotectedin otherways againstdeformationby the stressesand strainsimposed by its environment." 5 Thus, D'Arcy Thompson'ssecond theme (p. Io) becomesan aspect of his first--that animalsare well designed. Aristotle'sgreat student,in short, mixed up his causes. D'Arcy Thompson's errorcan be epitomizedthis way: He viewed physical cause of form;theyare, in fact,formalcauses or forcesas the efficient of optimum shapes that determinethe direction which blueprints naturalselection(the trueefficient cause) musttake to produce adaptation. If physicalforcesare not the kind of cause D'Arcy Thompson thought,theyare causes nonethelessand no explanationof formis complete withoutreferenceto them. He was rightto correlatephysical forceswithorganicformsand to claim thatthe correspondencewas no mereanalogy; but he was rightforthe wrongreason. D'Arcy Thomp47 Certain extinct corals (cited on p. 513), for example. When the individuals of a colony are crowded together,each assumes the hexagonal form that laws of closest packing require. When uncrowded, the individuals remain circular in outline. Since thereare no genetic differences(circular and hexagonal can occur within the same colony, always correlated to the extent of crowding), direct shaping by the pressuresof contact mustbe the efficientcause. 48 Surface-tensionsof cells have been measured directlyand they are too low to shape the cell. See J.T. Bonner, (note 2), p. 49. 49 The engineeringlibraryat Harvard, for example, has exiled all its pre-195o journals to a virtuallyunlit (and completelyunheated) attic. 50 Hutchinson,p. 58 i. This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions THOMPSON ANDTHE SCIENCEOF FORM D'ARCY 253 fortheefficient cause of good design;he son thoughthe had a theory us instead the science of basis for a gave form--ananalyticapproach to adaptation. IV. D'Arcy Thompson and the Science of Form The vindicationof D'Arcy Thompson'smethod.Amongbiologists, Growthand Formwearsthealbatrossof Berlioz'sLes Troyens;forit doomedby excessive has been regardedas an unusablemasterpiece of are Since books and subjectto no such length difficultyapplication. thechargeofexcessive ofstaging, as theeconomics constraint lengthis fornecessary morea lamentof busymenthanan argument neglect. in application, The chargeofdifficulty hasbeenquitejustified however, until recently.D'Arcy Thompson'smathematicalanalysisof form be considered simultaneously requiresthatall thepartsof an organism thetransforma-that changeofshapebe graspedas a wholethrough tionofcoordinates imposedoverentirebodies.D'ArcyThompsondrew hiscoordinate diagramsas pictures;he did not,becausehe couldnotin as mathematical useful expresany way,abstractthe transformations theonlypre-computer sions.Thus,Medawar,whoattempted quantifitermedthe techcationof transformed coordinates,51 quite properly unwieldy."52 nique"analytically The mathematical studyof growthand formhas been dominated of one organagainstanotherorgan bybivariateanalysis: theplotting in theory (or totalbodysize) duringgrowth.That thisis unsatisfactory has neverbeen denied,foran animalgrowsas a whole,notas an abtechstractedseriesof pairs. Whythenwas the obviously preferable all partssimultaneously-multivariate analysisnique of considering of multivariate not used? The theorems analysisare not new; many had been developedbeforeGrowthand Formreceiveditssecondedition. Buttheywerenotwidelyappliedbecausethesheerlaborofcalculationprecludedany practicalvalue. Withthe adventof electronic the situationhas changed completelyand multivariate computers, analysishas takena place amongthemostexcitingof new approachesin D'ArcyThompsonwas about one halfcenbiology.Unfortunately, turytoo early. His approach to formwas multivariatein conception; 51 P. B. Medawar,"Size, Shape and Age," in W. E. Le Gros Clark and P. B. Medawar (see footnote 4), pp. 157-87. 52 P. B. Medawar, in Ruth D'Arcy Thompson, (see footnote 2), p. 231. This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions NEW LITERARY HISTORY 254 henceitsuffered themisfortune ofmuchprophesy--it couldnotbe used initsowntime. has comeonlynow,and it has just D'ArcyThompson'svindication begun. I shallcitebut two amongseveralexcellentstudiesin multivariateanalysisthatwereinspireddirectly by Growthand Form.53In his chapteron the logarithmic spiral,D'ArcyThompsonpointedout formsof molluscan (p. 782) thatthe diverseand seemingly-complex in commonby just a fewbasic variables-the shellscan be generated curve(the apertureof a snail,forexample), shapeof thegenerating to theaxis itsrateofincreasein size,and itschangeofpositionrelative of coiling.Byvarying thesefewmeasures, thewholerange practically ofmolluscanformcan be simulated.ButD'ArcyThompsoncouldnot must do this,forthenumberofcombinations amongthebasicmeasures foranymeaningful runintothethousands analysis.A computercan generatetheseformsin seconds,and a tame machinecan even be trainedto draw(and shade!) eachsimulated shell(Fig 7). The result ..... ,, ':. 1:?. ? ? ,+:...' "snails." The sequence from a to d is generated by increasing the rate of whorl expansion and decreasing the rate of translationdown the axis. From D. M. Raup, "Computer as an aid in describing form in gastropod shells," Science, cxxxviii (1962), 150-52. FIo. 7. Computer drawn (and shaded) in mechanized butan important is no mereexercise contribuwizardry, of form-forit providesa matrixwithin tionto our understanding can be askedforthefirst time. Whenwe whichsomemajorquestions for of a generate completespectrum shapes, example,we quicklyfind thatactualshellsoccupybuta smallrangeofshapespossiblein theory. Whyare certainrealmsof shape unoccupied?David Raup has proof mebased upon theprinciples videdsomefascinating explanations chanicsandfunctional morphology. 54 53 A compendium of other examples will be found in my article "Evolutionary Paleontology and the Science of Form," Earth-Science Reviews, vi (1970), 77-I19. 54 D. M. Raup and A. Michelson, "Theoretical Morphology of the Coiled Shell," Science, cxlvii (1965), I294-95. D. M. Raup, "Geometric Analysisof Shell Coiling: General Problems,"Journal of Paleontology,xl (1966), 1 I78-90. This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions D'ARCY THOMPSON AND THE SCIENCE OF FORM 255 P. H. A. Sneath has recentlypublishedthe firstsuccessfulquantification of D'Arcy Thompson's transformedcoordinates.55He has done thiswith modificationsof a techniqueknownbest among geologiststrendsurfaceanalysis. In trendsurfaceanalysis,the distributionof a featureon a map (rainfallin mm per yearforexample) is abstractedby mathematical surfaces of increasing complexity. Sneath compares chimpanzeeand humanskulls. As his feature,he uses thegeometricdistance between each pair of correspondingpoints (tip of the chin for example); the undistortedcoordinatenet itselfservesas his map. The surfacesfittedto these distancesare expressionsof the total difference in shape betweentwo skulls. The differences are renderedas numbers, and thesecan be analyzed forpatternsthat expressthe simplestway to one complexobjectintoanother. transform D'Arcy Thompson would have welcomed the computermore as a perpetratorof his basic attitudesthan of his particulartechniques;for he realizedthatmen's theoriesare subtlymoldedby the machinerythey choose (or are constrained) to use. In particular,he feltthat the descriptivemethodof conventionaltaxonomy,thoughlauded by its practitionersas objective and atheoretic,impliesthe view that complexity is irreducible. For the morphologist, when comparingone organismwith another, describesthe differences betweenthempointby pointand 'character'by 'character.'If he is fromtimeto timeconstrainedto admitthe existence of 'correlation'betweencharacters.... yetall thewhilehe recognizesthis fact of correlationsomewhatvaguely,as a phenomenondue to causes which,exceptin rareinstances,he can hardlyhope to trace; and he falls and talkingof evolutionas thoughit had readilyintothehabitof thinking on his own the of lines proceeded descriptions, pointbypointand character character (p. I136). by In D'Arcy Thompson's approach, we do not seek a different explanation for each contrastbetweentwo organisms;by notingcorrelations, to the fewestfactorsneeded to generate we tryto reduce differences them. We do this not for the intellectualsatisfactionprovided by simplification,but because the abstracted systemof factors can be linkedmoreeasilyto cause. In likeningthehuman stomachto a bubble restrictedby a trammel,D'Arcy Thompson invokesthe glassblowerto explainitsform(p. 1o50) : startshis operationswitha tube,whichhe firstcloses The glass-blower at one end so as to forma hollowvesicle,withinwhichhisblastof air exerwhich cisesa uniform pressureon all sides;but thesphericalconformation Grids,"Journal Analysisof Transformation 55 P. H. A. Sneath,"Trend-Surface of Zoology, cli (1967), 65-122. This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions 256 NEW LITERARY HISTORY thisuniformexpansiveforcewould naturallytendto produceis modified ofresistances intoall kindsofformsbythetrammels setup as theworkman letsone part or anotherof his bubblebe unequallyheated or cooled. It was OliverWendellHolmeswho firstshowedthiscuriousparallelbetween theoperationsof theglass-blower and thoseof Nature,whenshe starts,as sheso oftendoes,witha simpletube.... Such a formas thatofthehuman stomachis easilyexplainedwhenit is regardedfromthispointof view; it is simplyan ill-blownbubble,a bubblethathas been renderedlopsidedby a trammelor restraint along one side,such a trammelas is producedif letsone side of hisbubblegetcold,and suchas is actually theglass-blower presentin the stomachitselfin the formof a muscularband. A science of form. Form and diversityare the two greatsubjectsof natural history.The studyof speciationand systematicshas given us a scienceof diversitywithinevolutionarytheory,but we have lacked a science of form.56I believe that a science of formis now arisingand that D'Arcy Thompson will be regarded as its godfatherbecause he anticipated and developed the two principlesupon which it will be based: i. Adult form,in all its complexity,shall not serve as a primary datum. It mustbe reducedto a smallerset of factorsthatcan generate it duringgrowth. Causes shall be sought among these factors,not in theirresults. D'Arcy Thompson renderedthesefactorseithertheoretically as the physicalforcesmolding formor pictoriallyas the simple coordinatenets. With the techniquesof compatternsof transformed we realize D'Arcy Thompson's unattainedgoal can simulation, puter of quantitativeexpressionforthesefactors. 2. When the "how" of formis explainedin (I), we mustachieve an equally rigoroussolutionforits "why." Yet thestudyof adaptationhas been plagued by vague, trivialand untestableproposals. We need a criterionof relativeefficiency-away to determinewhich of two structuresis betterdesignedto performthesame function.D'Arcy Thompson stressedthe mechanicalpropertiesof form. As we have seen (p. 286), he confusedhis causes; but when we view physicalforcesnot as the architectsof formbut as the blueprintsthat specifyoptimumshapes, we have our testfor relativeefficiency:the comparisonof an actual structurewithits optimumexpressedin an engineer'sterms. 56 I have mentioned several reasons for this in various parts of this work: previous lack of a technologyto handle the calculations of multivariate analysis (p. 287); the eclipse of functional anatomy by evolutionary theory and its use of formonly for the tracingof lineages (p. 266) ; the attitude towards formimplicitin the part-by-partdescriptionsof conventionaltaxonomy (p. 267). I presentthis general argumentmore fullyin the article cited in note 53. This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions D'ARCY THOMPSON AND THE SCIENCE OF FORM 257 Withthesetwo analyticaltools,a scienceof formcan provideinsightsintothemajoreventsof life'shistory.As one example,the atof strikingly tainment similarexternalshapesby animalsof verydifferentancestry57 of convergence-isrecordedwith -the phenomenon in the fossil record. In has called fact,Sylvester-Bradley greatfrequency itsrecognition "themostdistinctive contribution thatpaleontology has made to modernevolutionary Older naturalists were synthesis.""58 eitheran exampleofGod's plan or an orproneto see in convergence forideal form.Today, no one would seek any other ganic striving cause thannaturalselection;yetfinalcausesoftenremainas efficient intractable as ever. D'ArcyThompson,however,provideda general of mechanicsspecify a limitednumberof explanation:theprinciples for the solution of common good designs problemsfacedby animals. Thesecan be determined a priori,and usedto predicttheformsofundiscoveredorganismsperforming specifiedfunctions.What seemed can be and even mysterious explained predicted. Our argumentindicates. . . that evolutionary changes,occurringon a comparatively fewdefinite ofphysico-mathelines,orplainalternatives, maticalprobability, are likelyto repeatthemselves:thatthe "higher" forinstance, notfromorthrough oneanother, mayhavesprung protozoa, fromthe simplerforms;or thatthe worm-type, to take but severally another example, mayhavecomeintobeingagainandagain(p. 1095). forthatis illustrated It is easyto assessD'ArcyThompson's influence; the of his use work in the technical researchof distinby continuing and by thelocationof hismainideas at thecoreof guishedscientists, an emerging scienceof form.It is muchmoredifficult, however,to measurehisgreatness; forhe statednothing and in new, truly novelty the is criterion used most scientists status. in discovery by assigning Growthand Form is an ingeniouscompendium of classicalwisdom fromthelater,butscarcely withinsights modern,age ofGalitempered lean mechanics.To see it as a greatwork,we mustabandontheusual of noveltyand admitthattheunionof previously unconconception nectedtruthscan be an intellectual as brilliant and as imdiscovery the of as disclosure unknown. And portant something formerly D'Arcy knownin Thompsondid notmerelyunitea seriesof truthsgenerally theirisolatedstate;he combinedtruths longforgotten byhiscolleagues. 57 Standard examples include the attainment of cup-coral shapes by a Permian brachiopod and a Jurassic clam and numerous correspondencesbetween Australian marsupials and placentals of the major continents (mole and marsupial "mole" for example). 58 P. C. Sylvester-Bradley,"Iterative Evolution in Fossil Oysters," Proceedings, International Zoological Congress,I (1959), 193. This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions 258 NEW LITERARY HISTORY Thereare somenotionsso abidingin man'sviewof naturethatwe can scarcelydenytheirstatusas aspectsof realityor as wayswe must perceivetheworld.I wouldplacehere,forexample,theidea thatanimalsare oftenexquisitely designedto do whattheydo. Such a notion at varioustimes(God, chance,natural receivesdifferent explanations even it be cast asidefora timewhena newscientific selection); may fashionrashlydismisses it with a properlydiscardedtheoryforits Yet it returns, forit must.And,whenit returns, scienexplanation.59 tistsrediscover whattheirforgotten knew better perhaps predecessors thanthey.D'ArcyThompsonwas greatbecausehe had notforgotten. MUSEUM OF COMPARATIVE ZOOLOGY, HARVARD UNIVERSITY 59 It is still unfashionable, in biological circles, to use such words as "design," "purpose," or "teleology." Since final cause is so indispensable a concept in the elucidation of adaptation, and since natural selection can produce a well-designed structurewithout any conscious interventionof God's super-humanwisdom or the sub-human intelligenceof the animal in question, one would think that these terms would again be admitted into orthodoxy. Evidently, however, in our choice of words, we are still fightingthe battle with theologians that we won in deeds almost a centuryago. This content downloaded from 134.84.3.112 on Wed, 22 Apr 2015 15:47:09 UTC All use subject to JSTOR Terms and Conditions
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