Produced by Dave Gowan dgowanbiofsueduSpecies and VarietiesTheir Origin by MutationLectures delivered at the University of CaliforniaByHugo DeVriesProfessor of Botany in the University of AmsterdamEdited byDaniel Trembly MacDougalDirector Department of Botanical ResearchCarnegie Institution of WashingtonSecond EditionCorrected and RevisedCHICAGOThe Open Court Publishing CompanyLONDONKegan Paul Trench Trubner and Co Ltd1906    COPYRIGHT 1904BYThe Open Court Pub CoCHICAGO    THE ORIGIN OF SPECIESThe origin of species is a natural phenomenonLAMARCKThe origin of species is an object of inquiryDARWINThe origin of species is an object of experimental investigationDeVRIES    PREFACE BY THE AUTHORTHE purpose of these lectures is to point out the means and methods bywhich the origin of species and varieties may become an object forexperimental inquiry in the interest of agricultural and horticulturalpractice as well as in that of general biologic science Comparativestudies have contributed all the evidence hitherto adduced for thesupport of the Darwinian theory of descent and given us some generalideas about the main lines of the pedigree of the vegetable kingdom butthe way in which one species originates from another has not beenadequately explained The current belief assumes that species are slowlychanged into new types In contradiction to this conception the theoryof mutation assumes that new species and varieties are produced fromexisting forms by sudden leaps The parenttype itself remains unchangedthroughout this process and may repeatedly give birth to new formsThese may arise simultaneously and in groups or separately at more orless widely distant periodsThe principal features of the theory of mutation have been dealt with atlength in my book Die Mutationstheorie Vol I 1901 Vol II 1903Leipsic Veit  Co in which I have endeavored to present ascompletely as possible the detailed evidence obtained from trustworthyhistorical records and from my own experimental researches upon whichthe theory is basedThe University of California invited me to deliver a series of lectureson this subject at Berkeley during the vii summer of 1904 and theselectures are offered in this form to a public now thoroughly interestedin the progress of modern ideas on evolution Some of my experiments andpedigreecultures are described here in a manner similar to that used inthe Mutationstheorie but partly abridged and partly elaborated inorder to give a clear conception of their extent and scope Newexperiments and observations have been added and a wider choice of thematerial afforded by the more recent current literature has been made inthe interest of a clear representation of the leading ideas leaving theexact and detailed proofs thereof to the students of the larger bookScientific demonstration is often long and encumbered with difficultpoints of minor importance In these lectures I have tried to devoteattention to the more important phases of the subject and have avoidedthe details of lesser interest to the general readerConsiderable care has been bestowed upon the indication of the lacunaein our knowledge of the subject and the methods by which they may befilled Many interesting observations bearing upon the little knownparts of the subject may be made with limited facilities either in thegarden or upon the wild flora Accuracy and perseverance and a warmlove for Natures children are here the chief requirements in suchinvestigationsIn his admirable treatise on Evolution and Adaptation New YorkMacmillan  Co 1903 Thomas Hunt Morgan has dealt in a criticalmanner with many of the speculations upon problems subsidiary to thetheory of descent in so convincing and complete a manner that I thinkmyself justified in neglecting these questions here His book gives anaccurate survey of them all and is easily understood by the generalreaderIn concluding I have to offer my thanks to Dr DT MacDougal and MissAM Vail of the New York Botanical Garden for their painstaking work inthe preparation of the manuscript for the press Dr MacDougal byviii his publications has introduced my results to his Americancolleagues and moreover by his cultures of the mutative species of thegreat eveningprimrose has contributed additional proof of the validityof my views which will go far to obviate the difficulties which arestill in the way of a more universal acceptation of the theory ofmutation My work claims to be in full accord with the principles laiddown by Darwin and to give a thorough and sharp analysis of some of theideas of variability inheritance selection and mutation which werenecessarily vague at his time It is only just to state that Darwinestablished so broad a basis for scientific research upon thesesubjects that after half a century many problems of major interestremain to be taken up The work now demanding our attention ismanifestly that of the experimental observation and control of theorigin of species The principal object of these lectures is to secure amore general appreciation of this kind of workHUGO DE VRIESAmsterdam October 1904ixPREFACE BY THE EDITORPROFESSOR DE VRIES has rendered an additional service to all naturalistsby the preparation of the lectures on mutation published in the presentvolume A perusal of the lectures will show that the subject matter ofDie Mutationstheorie has been presented in a somewhat condensed formand that the time which has elapsed since the original was prepared hasgiven opportunity for the acquisition of additional facts and areexamination of some of the more important conclusions with the resultthat a notable gain has been made in the treatment of some complicatedproblemsIt is hoped that the appearance of this English version of the theory ofmutation will do much to stimulate investigation of the various phasesof the subject This volume however is by no means intended toreplace as a work of reference the larger book with its detailedrecital of facts and its comprehensive records but it may prove asubstitute for the use of the general readerThe revision of the lectures has been a task attended with no littlepleasure especially since it has given the editor the opportunity foran advance consideration of some of the more recent results thusmaterially facilitating investigations which have been in progress atthe New York Botanical Garden for some time So far as the ground hasbeen covered the researches in question corroborate the conclusions ofde Vries in all important particulars The preparation of the manuscriptfor the printer