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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 ***

Produced by Dave Gowan

Species and Varieties

Their Origin by Mutation

Lectures delivered at the University ofCalifornia

Director Department of Botanical

-THE ORIGIN OF SPECIES

The origin of species is a naturalphenomenon

-PREFACE BY THE AUTHOR

THE purpose of these lectures is to pointout the means and methods by which theorigin of species and varieties may

become an object for experimental

inquiry, in the interest of agricultural andhorticultural practice as well as in that ofgeneral biologic science Comparativestudies have contributed all the evidencehitherto adduced for the support of theDarwinian theory of descent and given ussome general ideas about the main lines ofthe pedigree of the vegetable kingdom, butthe way in which one species originatesfrom another has not been adequatelyexplained The current belief assumes thatspecies are slowly changed into new

types In contradiction to this conceptionthe theory of mutation assumes that newspecies and varieties are produced fromexisting forms by sudden leaps The

parent-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

The principal features of the theory ofmutation have been dealt with at length in

my book "Die Mutationstheorie" (Vol I.,

1901, Vol II., 1903 Leipsic, Veit & Co.),

in which I have endeavored to present ascompletely as possible the detailed

evidence obtained from trustworthy

historical records, and from my own

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 of

1904, and these lectures are offered in thisform to a public now thoroughly interested

in the progress of modern ideas on

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

"Mutationstheorie," but partly abridgedand partly elaborated, in order to give aclear conception of their extent and scope.New experiments and observations havebeen added, and a wider choice of thematerial afforded by the more recent

current literature has been made in the

interest of a clear representation of theleading ideas, leaving the exact and

detailed proofs thereof to the students ofthe larger book

Scientific demonstration is often long andencumbered with difficult points of minorimportance In these lectures I have tried

to 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 methods

by which they may be filled Many

interesting observations bearing upon thelittle known parts of the subject may be

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

requirements 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

In concluding I have to offer my thanks to

Dr D.T MacDougal and Miss A.M Vail

of the New York Botanical Garden fortheir painstaking work in the preparation

of the manuscript for the press Dr

MacDougal, by [viii] his publications, hasintroduced my results to his Americancolleagues, and moreover by his cultures

of the mutative species of the great

evening-primrose has contributed

additional 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 theory

of 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

variability, inheritance, selection, andmutation, which were necessarily vague at

his time It is only just to state, that

Darwin established so broad a basis forscientific research upon these subjects,that after half a century many problems ofmajor interest remain to be taken up Thework now demanding our attention ismanifestly that of the experimental

observation and control of the origin ofspecies The principal object of theselectures is to secure a more general

appreciation of this kind of work

PROFESSOR DE VRIES has rendered anadditional service to all naturalists by thepreparation of the lectures on mutationpublished in the present volume A

perusal 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

It is hoped that the appearance of thisEnglish version of the theory of mutationwill do much to stimulate investigation of

the various phases of the subject Thisvolume, however, is by no means intended

to 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

The revision of the lectures has been atask attended with no little pleasure,

especially since it has given the editor theopportunity for an advance consideration

of some of the more recent results, thusmaterially facilitating investigations

which have been in progress at the NewYork Botanical Garden for some time Sofar as the ground has been covered theresearches in question corroborate theconclusions of de Vries in all important

particulars The preparation of the

manuscript 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 preserved

as 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

New York Botanical Garden, October,1904

PREFACE TO THE SECOND

EDITION.

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 used

to 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 order

to avoid confusion as to the identity ofsome of the plants which figure

prominently in the experimental

investigations in Amsterdam and NewYork

The portrait which forms the frontispiece

is a reproduction of a photograph taken byProfessor F.E Lloyd and Dr W.A

Cannon during the visit of Professor deVries at the Desert Botanical Laboratory

of the Carnegie Institution, at Tucson,Arizona, in June, 1904

D T MACDOUGAL

December 15, 1905

CONTENTS

A INTRODUCTION.

LECTURE PAGE

I Descent: theories of evolution and

methods 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 Viola tricolor, Draba verna, Primula acaulis, and other examples Euphorbia

pecacuanha Prunus maritima.

Taraxacum and Hieracium.

III Elementary species of cultivated

plants 63

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 the

Romans 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 of

composites [xiii] Progressive red

varieties Apparent losses Xanthium canadense Correlative variability.

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 185

Vicinism or variation under the influence

of pollination by neighboring individuals.Vicinism in nurseries Purifying new andold varieties A case of running out ofcorn in Germany

VIII Latent characters 216 Leaves ofseedlings, adventitious buds, systematic

latency and retrogressive evolution.

Degressive evolution Latency of specificand varietal characters in wheat-ear

carnation, in the green dahlias, in whitecampanulas and others Systematic latency

of flower colors

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

Constant hybrids of Oenothera muricata and 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.

Mendel's laws Unit- characters

XIII Polycephalic poppies 369

Permanency and high variability

Sensitive period of the anomaly

Dependency on external conditions

XIV Monstrosities 400 Inheritance ofmonstrosities Half races and middleraces Hereditary value of atavists

Twisted stems and fasciations Middleraces of tricotyls and syncotyls Selection

by the hereditary percentage among theoffspring

XV Double adaptations 430 Analogybetween double adaptations and

anomalous middle races Polygonum amphibium Alpine plants Othonna crassifolia Leaves in sunshine and

shadow Giants and dwarfs Figs and ivy.Leaves of seedlings

E MUTATIONS.

XVI Origin of the peloric toad-flax 459Sudden and frequent origin in the wildstate Origin in the experiment-garden.Law of repeated mutations Probable

origin of other pelories.

evidence Experimental origin of

Chrysanthemum segetum plenum.

Dependency upon nourishment Petalody

of stamens

XVIII New species of Oenothera 516 Mutations of Oenothera lamarckiana in

the wild state near Hilversum New

varieties of O laevifolia, O brevistylis, and O nanella New elementary species,

O gigas, O rubrinervis, albida, and oblonga O lata, a pistillate form.

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 Hibiscus Moscheutos Purple beech.

Monophyllous strawberries Chances ofsuccess with new mutations

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 Geranium

praetense in the experiment-garden.

XXII Systematic atavism 630

Reappearance of ancestral characters

Primula acaulis umbellata.

Bracts of crucifers Zea Mays

cryptosperma Equisetum, Dipsacus sylvestris torsus Tomatoes.

XXIII Taxonomic anomalies 658

Specific characters occurring in other

cases as casual anomalies Papaver

bracteatum monopetalum Desmodium gyrans and monophyllous varieties.

Peltate leaves and ascidia Flowers on

leaves Leaves Hordeum trifurcatum.

XXIV Hypothesis of periodical

mutations 686

Discovering mutable strains Periods

of mutability and constancy

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

organic kingdom

F FLUCTUATIONS.

XXV General laws of fluctuations 715 Fluctuating variability Quetelet's law.Individual and partial

fluctuations Linear variability Influence

XXVII Inconstancy of improved races

770 Larger variability in the case ofpropagation by seed, progression andregression after a single selection, andafter repeated selections Selection

experiments with corn Advantages andeffect of repeated selection.

XXVIII Artificial and natural selection

798 Conclusions Specific and specific selection Natural selection in thefield Acclimatization Improvement-selection of sugar-beets by various

intra-methods Rye Hereditary percentage andcentgener power as marks by which

intraspecific selection may be guided.Index 827

[1] A INTRODUCTION

LECTURE I

DESCENT: THEORIES OF EVOLUTION AND METHODS OF INVESTIGATION

Newton convinced his contemporaries thatnatural laws rule the whole universe.Lyell showed, by his principle of slowand gradual evolution, that natural lawshave reigned since the beginning of time

To Darwin we owe the almost universalacceptance of the theory of descent

This doctrine is one of the most notedlandmarks in the advance of science Itteaches the validity of natural laws of life

in its broadest sense, and crowns the

philosophy founded by Newton and Lyell.Lamarck proposed the hypothesis of acommon origin of all living beings and

this ingenious and thoroughly

philosophical conception was warmlywelcomed by his partisans, but was notwidely accepted owing to lack of

supporting evidence To Darwin wasreserved the task of [2] bringing the theory

of common descent to its present high rank

in scientific and social philosophy

Two main features in his work have

contributed 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

The universal belief in the independent

creation of living organisms was revised

by Linnaeus and was put upon a new

foundation 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,

which were in their turn, supposed to haveevolved from species by the commonmethod

Darwin tried to show that the links whichbind species to genera are of the samenature as those which determine the

relationship of [3] subspecies and

varieties 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

further, and this step was an important anddecisive one He showed that the relationbetween the various genera of a familydoes not exhibit any features of a natureother than that between the species of agenus What has been conceded for theone must needs be accepted for the other.The same holds good for the large groups

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 aid

of this principle; without it, all similarity

is only apparent and accidental

Geographic and paleontologic facts,

brought together by Darwin and others on

a previously unequalled scale, point

clearly in the same direction The vastamount of evidence of all [4] comparative

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 of

descent are now accepted as the basis ofall biological science Half a century ofdiscussion and investigation has cleared

up the minor points and brought out anabundance of facts; but they have notchanged the principle Descent with

modification is now universally accepted

as the chief law of nature in the organicworld In honor of him, who with

unsurpassed genius, and by unlimitedlabor has made it the basis of modernthought, this law is called the "Darwiniantheory of descent."

Darwin's second contribution to this

attainment was his proof of the possibility

of a physiological explanation of theprocess of descent itself Of this

possibility he fully convinced his

contemporaries, 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,

objections have been raised from the veryoutset, and with such force as to compelDarwin himself to change his views in hislater writings This however, was of noavail, and objections and criticisms havesince steadily accumulated Physiologicfacts concerning the origin of [5] species

in nature were unknown in the time ofDarwin It was a happy idea to choose the

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 prudent

to 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

veneration for Darwin, as to describe as

Darwinism some things, which in myopinion, had never been a part of

Darwin's conceptions

The experience of the breeders was quiteinadequate to the use which Darwin made

of 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

purposes, but science needed a clearunderstanding of the [6] factors in thegeneral process of variation RepeatedlyDarwin tried to formulate these causes,but the evidence available did not meethis requirements