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Author: Hugo DeVries

Release Date: January, 2005 [EBook#7234] [Yes, we are more than one yearahead of schedule] [This file was firstposted on March 30, 2003]

Edition: 10

Language: English

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GUTENBERG EBOOK SPECIES ANDVARIETIES ***

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<dgowan@bio.fsu.edu>

Species and VarietiesTheir Origin by Mutation

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CHICAGO

-THE ORIGIN OF SPECIES

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-PREFACE BY THE AUTHOR

THE purpose of these lectures is to pointout the means and methods by which theorigin of species and varieties maybecome an object for experimental

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types In contradiction to this conceptionthe theory of mutation assumes that newspecies and varieties are produced fromexisting forms by sudden leaps Theparent-type itself remains unchangedthroughout this process, and may

repeatedly give birth to new forms Thesemay arise simultaneously and in groups orseparately at more or less widely distantperiods.

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experimental researches, upon which thetheory is based.

The University of California invited me todeliver a series of lectures on this subject,at Berkeley, during the [vii] summer of1904, and these lectures are offered in thisform to a public now thoroughly interestedin the progress of modern ideas on

evolution Some of my experiments andpedigree-cultures are described here in amanner similar to that used in the

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interest of a clear representation of theleading ideas, leaving the exact anddetailed proofs thereof to the students ofthe larger book.

Scientific demonstration is often long andencumbered with difficult points of minorimportance In these lectures I have triedto devote attention to the more importantphases of the subject and have avoided thedetails of lesser interest to the generalreader.

Considerable care has been bestowedupon the indication of the lacunae in ourknowledge of the subject and the methodsby which they may be filled Many

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made with limited facilities, either in thegarden or upon the wild flora Accuracyand perseverance, and a warm love forNature's children are here the chiefrequirements in such investigations.

In his admirable treatise on Evolution andAdaptation (New York, Macmillan & Co.,1903), Thomas Hunt Morgan has dealt in acritical manner with many of the

speculations upon problems subsidiary tothe theory of descent, in so convincing andcomplete a manner, that I think myselfjustified in neglecting these questionshere His book gives an accurate survey ofthem all, and is easily understood by thegeneral reader.

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Dr D.T MacDougal and Miss A.M Vailof the New York Botanical Garden fortheir painstaking work in the preparationof the manuscript for the press Dr.

MacDougal, by [viii] his publications, hasintroduced my results to his Americancolleagues, and moreover by his culturesof the mutative species of the great

evening-primrose has contributedadditional proof of the validity of myviews, which will go far to obviate thedifficulties, which are still in the way of amore universal acceptation of the theoryof mutation My work claims to be in fullaccord with the principles laid down byDarwin, and to give a thorough and sharpanalysis of some of the ideas of

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PROFESSOR DE VRIES has rendered anadditional service to all naturalists by thepreparation of the lectures on mutationpublished in the present volume Aperusal of the lectures will show that thesubject matter of "Die Mutationstheorie"has been presented in a somewhat

condensed form, and that the time whichhas elapsed since the original was

prepared has given opportunity for theacquisition of additional facts, and a re-examination of some of the more importantconclusions with the result that a notablegain has been made in the treatment ofsome complicated problems.

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the various phases of the subject Thisvolume, however, is by no means intendedto replace, as a work of reference, thelarger book with its detailed recital offacts and its comprehensive records, but itmay prove a substitute for the use of thegeneral reader.

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particulars The preparation of themanuscript for the printer has consistedchiefly in the adaptation of oral [xii]discussions and demonstrations to a formsuitable for permanent record, togetherwith certain other alterations which havebeen duly submitted to the author Theoriginal phraseology has been preservedas far as possible The editor wishes toacknowledge material assistance in thiswork from Miss A.M Vail, Librarian ofthe New York Botanical Garden.

D.T MacDougal.

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PREFACE TO THE SECONDEDITION.

THE constantly increasing interest in allphases of evolution has made necessarythe preparation of a second edition of thisbook within a few months after the firstappeared The opportunity has been usedto eliminate typographical errors, and tomake alterations in the form of a fewsentences for the sake of clearness andsmoothness The subject matter remainspractically unchanged An explanatorynote has been added on page 575 in orderto avoid confusion as to the identity ofsome of the plants which figure

prominently in the experimental

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The portrait which forms the frontispieceis a reproduction of a photograph taken byProfessor F.E Lloyd and Dr W.A.

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LECTURE PAGE

I Descent: theories of evolution andmethods of investigation 1 The theory ofdescent and of natural selection Evolutionand adaptation Elementary species andvarieties Methods of scientific pedigree-culture.

B ELEMENTARY SPECIES.

II Elementary species in nature 32 Violatricolor, Draba verna, Primula acaulis,and other examples Euphorbia

pecacuanha Prunus maritima.Taraxacum and Hieracium.

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Beets, apples, pears, clover, flax andcoconut.

IV Selection of elementary species 92 Cereals Le Couteur Running out ofvarieties Rimpau and

Risler, Avena fatua Meadows Old

Egyptian cereals Selection by theRomans Shirreff Hays.

C RETROGRADE VARIETIES.

V Characters of retrograde varieties 121Seed varieties of pure, not hybrid origin.Differences from elementary species.Latent characters Ray-florets ofcomposites [xiii] Progressive red

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Laciniate leaves and petals Compoundcharacters.

VI Stability and real atavism 154 Constancy of retrograde varieties.

Atavism in Ribes sanguineum

Albidum, in conifers, in Iris pallida.Seedlings of Acacia.

Reversion by buds.

VII Ordinary or false atavism 185Vicinism or variation under the influenceof pollination by neighboring individuals.Vicinism in nurseries Purifying new andold varieties A case of running out ofcorn in Germany.

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latency and retrogressive evolution.Degressive evolution Latency of specificand varietal characters in wheat-earcarnation, in the green dahlias, in whitecampanulas and others Systematic latencyof flower colors.

IX Crossing of species and varieties 247 Balanced and unbalanced, or speciesand variety crosses.

Constant hybrids of Oenothera muricataand O biennis Aegilops,

Medicago, brambles and other instances.

X Mendel's law of balanced crosses 276Pairs of antagonistic characters, one

active and one latent Papaver

somniferum [xiv] Mephisto Danebrog.

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D EVERSPORTING VARIETIES.

XI Striped flowers 309 Antirrhinummajus luteum rubro-striatum with

pedigree Striped flowers, fruits andradishes Double stocks.

XII "Five leaved" clover 340 Origin ofthis variety Periodicity of the anomaly.Pedigree- cultures Ascidia.

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Twisted stems and fasciations Middleraces of tricotyls and syncotyls Selectionby the hereditary percentage among theoffspring.

XV Double adaptations 430 Analogybetween double adaptations and

anomalous middle races Polygonumamphibium Alpine plants Othonnacrassifolia Leaves in sunshine and

shadow Giants and dwarfs Figs and ivy.Leaves of seedlings.

E MUTATIONS.

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origin of other pelories.[xv]XVII The production of double flowers.488 Sudden appearance of double flowersin horticulture Historical

evidence Experimental origin of

Chrysanthemum segetum plenum.

Dependency upon nourishment Petalodyof stamens.

XVIII New species of Oenothera 516Mutations of Oenothera lamarckiana in

the wild state near Hilversum New

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Inconstancy of O scintillans.

XIX Experimental pedigree-cultures 547Pedigree of the mutative products of

Oenothera lamarckiana in the Botanical

Garden at Amsterdam Laws of mutability.Sudden and repeated leaps from an

unchanging main strain Constancy of thenew forms Mutations in all directions.XX Origin of wild species and varieties.576

Problems to solve Capsella heegeri.Oenothera biennis cruciata.

Epilobium hirsutum cruciatum HibiscusMoscheutos Purple beech.

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XXI Mutations in horticulture 604

Chelidonium majus lacinatum Dwarf

and spineless varieties Laciniate leaves.Monophyllous and broom-like varieties.

[xvi] Purple leaves Celosia Italian

poplar Cactus dahlia Mutative origin of

Dahlia fistulosa, and Geraniumpraetense in the experiment-garden.

XXII Systematic atavism 630

Reappearance of ancestral characters.

Primula acaulis umbellata.Bracts of crucifers Zea Mays

cryptosperma Equisetum, Dipsacussylvestris torsus Tomatoes.

XXIII Taxonomic anomalies 658Specific characters occurring in other

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bracteatum monopetalum Desmodiumgyrans and monophyllous varieties.

Peltate leaves and ascidia Flowers on

leaves Leaves Hordeum trifurcatum.

XXIV Hypothesis of periodicalmutations 686

Discovering mutable strains Periodsof mutability and constancy.

Periods of mutations Genealogical trees.Limited life-time of the

organic kingdom.

F FLUCTUATIONS.

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fluctuations Linear variability Influenceof nutrition.Periodicity curves.XXVI Asexual multiplication ofextremes 742 Selection between species and intra-specific selection.Excluding individual [xvii] embryonicvariability Sugar-canes.

Flowering cannas Double lilacs Otherinstances Burbank's method

of selection.

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experiments with corn Advantages andeffect of repeated selection.

XXVIII Artificial and natural selection.798 Conclusions Specific and intra-specific selection Natural selection in thefield Acclimatization Improvement-selection of sugar-beets by various

methods Rye Hereditary percentage andcentgener power as marks by whichintraspecific selection may be guided.Index 827

[1] A INTRODUCTION

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DESCENT: THEORIES OF EVOLUTIONAND METHODS OF INVESTIGATION

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this ingenious and thoroughly

philosophical conception was warmlywelcomed by his partisans, but was notwidely accepted owing to lack ofsupporting evidence To Darwin wasreserved the task of [2] bringing the theoryof common descent to its present high rankin scientific and social philosophy.

Two main features in his work havecontributed to this early and unexpectedvictory One of them is the almost

unlimited amount of comparative

evidence, the other is his demonstration ofthe possibility of a physiological

explanation of the process of descentitself.

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creation of living organisms was revisedby Linnaeus and was put upon a newfoundation Before him the genera weresupposed to be created, the species andminor forms having arisen from themthrough the agency of external conditions.In his first book Linnaeus adhered to thisbelief, but later changed his mind andmaintained the principle of the separatecreation of species The weight of hisauthority soon brought this conception touniversal acceptance, and up to the

present time the prevailing conception of aspecies has been chiefly based on thedefinition given by Linnaeus His speciescomprised subspecies and varieties,

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Darwin tried to show that the links whichbind species to genera are of the samenature as those which determine therelationship of [3] subspecies andvarieties If an origin by natural laws isconceded for the latter, it must on thisground be granted for the first also In thisdiscussion he simply returned to the pre-Linnean attitude But his material wassuch as to allow him to go one step

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The conviction of the common origin ofclosely allied forms necessarily leads tothe conception of a similar descent even inremote relationships.

The origin of subspecies and varieties asfound in nature was not proved, but onlygenerally recognized as evident A

broader knowledge has brought about thesame state of opinion for greater groups ofrelationships Systematic affinities findtheir one possible explanation by the aidof this principle; without it, all similarityis only apparent and accidental.

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sciences compels us to accept the idea Todeny it, is to give up all opportunity ofconceiving Nature in her true form.The general features of the theory ofdescent are now accepted as the basis ofall biological science Half a century ofdiscussion and investigation has clearedup the minor points and brought out anabundance of facts; but they have notchanged the principle Descent withmodification is now universally acceptedas the chief law of nature in the organicworld In honor of him, who with

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Darwin's second contribution to this

attainment was his proof of the possibilityof a physiological explanation of theprocess of descent itself Of thispossibility he fully convinced hiscontemporaries, but in indicating theparticular means by which the change ofspecies has been brought about, he has notsucceeded in securing universal

acceptation Quite on the contrary,

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experience of the breeders in the

production of new varieties, as a basis onwhich to build an explanation of the

processes of nature In my opinion Darwinwas quite right, and he has succeeded ingiving the desired proof But the basiswas a frail one, and would not stand tooclose an examination Of this Darwin wasalways well aware He has been prudentto the utmost, leaving many points

undecided, and among them especially therange of validity of his several arguments.Unfortunately this prudence has not beenadopted by his followers Without

sufficient warrant they have laid stress onone phase of the problem, quite

overlooking the others Wallace has evengone so far in his zeal and ardent

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Darwinism some things, which in myopinion, had never been a part ofDarwin's conceptions.

The experience of the breeders was quiteinadequate to the use which Darwin madeof it It was neither scientific, nor

critically accurate Laws of variationwere barely conjectured; the differenttypes of variability were only imperfectlydistinguished The breeders' conceptionwas fairly sufficient for practical