BOUGHT WITH THE INCOME FROM THE SAGE ENDOWMENT FUND THE GIFT OF Hetirg W. Sage 1891 .md//>3f. vkmU - 5901 '"' '«n. # Cornell University Library The original of tiiis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924024538062 «ij o,.- .%?*" University Library QH 366.V98 1906 Species and varieties, their origin by 3 1924 024 538 062 species and Varieties Their Origin by Mutation Lectures Delivered at the University of California by Hugo DeVries Professor of Botany in the'^niversity of Amsterdam Edited by Daniel Trembly MacDougal Director Department of Botanical Research, Carnegie Institution of Wasliington Second Edition, Corrected and Revised CHICAGO The Open Court Publishing Company LONDON Kegan Paul, Trench, Trubner & Co., Ltd. 1906 QH Copyright 1904 BY The Open Court Pub. Co. Chicago THE ORIGIN OF SPECIES The origin of species is a natural phenomenon. Lamaeok. The origin of species is an ohject of inquiry. Darwin. The origin of species is an ohject of experi- mental investigation. DeVries. PREFACE BY THE AUTHOE The purpose of these lectures is to point out the means and methods by which the origin of species and varieties may become an object for experimental inquiry, in the interest of agricultural and horticultural practice as well as in that of general biologic science. .' Comparative studies have contributed all the evidence hitherto adduced for the support of the Darwinian theory of descent and given us some general ideas about the main lines of the pedigree of the vegetable kingdom, but the way in which one species originates from another has not been ade- quately explained. The current belief assumes that spe- cies are slowly changed into new tjrpes. In contradiction to this conception the theory of mutation assumes that new species and varieties are produced from existing forms by sudden leaps. The parent-type itself remains unchanged throughout this process, and may repeatedly give birth to new forms. These may arise simultaneously and in groups or separately at more or less widely dis- tant periods. The principal features of the theory of mutation have been dealt with at length in my book "Die Mutations- theorie" (Vol. I., 1901, Vol. II., 1903. Leipsic, Veit & Co.), in which I have endeavored to present as com- pletely as possible the detailed evidence obtained from trustworthy historical records, and from my own experi- mental researches, upon which the theory is based. The University of California invited me to deliver a series of lectures on this subject, at Berkeley, during the vii viii Preface by the Author summer of 1904, and these lectures are offered in this form to a public now thoroughly interested in the pro- gress of modern ideas on evolution. Some of my experi- ments and pedigree-cultures are described here in a man- ner similar to that used in the " Mutationstheorie," but partly abridged and partly elaborated, in order to give a clear conception of their extent and scope. New experi- ments and observations have been added, and a wider choice of the material afforded by the more recent cur- rent literature has been made in the interest of a clear representation of the leading ideas, leaving the exact and detailed proofs thereof to the students of the larger book. Scientific demonstration is often long and encumbered with difficult points of minor importance. In these lec- tures I have tried to devote attention to the more im- portant phases of the subject and have avoided the de- tails of lesser interest to the general reader. Considerable care has been bestowed upon the indica- tion of the lacunae in our knowledge of the subject and the methods by which they may be filled. Many inter- esting observations bearing upon the little knovm parts of the subject may be made with limited facilities, either in the garden or upon the wild flora. Accuracy and per- severance, and a warm love for Nature's children are here the chief requirements in such investigations. In his admirable treatise on Evolution and Adaptation (New York, Macmillan & Co., 1903), Thomas Hunt Mor- gan has dealt in a critical manner with many of the speculations upon problems subsidiary to the theory of descent, in so convincing and complete a manner, that I think myself justified in neglecting these questions here. His book gives an accurate survey of them all, and is easily understood by the general reader. In concluding I have to offer my thanks to Dr. D. T. MacDougal and Miss A. M. Vail of the New York Botan- ical Garden for their painstaking work in the prepara- tion of the manuscript for the press. Dr. MacDougal, by Preface by the Author ix his publications, has introduced my results to his Ameri- can colleagues, and moreover by his cultures of the muta- tive species of the great evening-primrose has con- tributed additional proof of the validity of my viev^s, which will go far to obviate the dif&culties, which are still in the way of a more universal acceptation of the theory of mutation. My work claims to be in full ac- cord with the principles laid down by Darwin, and to give a thorough and sharp analysis of some of the ideas of variability, inheritance, selection, and mutation, which were necessarily vague at his time. It is only just to state, that Darwin established so broad a basis for scien- tific research upon these subjects, that after half a century many problems of major interest remain to be taken up. The work now demanding our attention is manifestly that of the experimental observation and control of the origin of species. The principal object of these lectures is to secure a more general appreciation of this kind of work. ^ Hugo de Vries. Amsterdam, October, 1904- PREFACE BY THE EDITOR Peofessob de Vries has rendered an additional service to all naturalists by the preparation of the lectures on mutation published in the present volume. A perusal of the lectures will show that the subject-matter of "Die Mutationstheorie " has been presented in a somewhat condensed form, and that the time which has elapsed since the original was prepared has given opportunity for the acquisition of additional facts, and a re-examination of some of the more important conclusions with the re- sult that a notable gain has been made in the treatment of some complicated problems. It is hoped that the appearance of this English version of the theory of mutation will do much to stimulate in- vestigation of the various phases of the subject. This volume, however, is by no means intended to replace, as a work of reference, the larger book with its detailed recital of facts and its comprehensive records, but it may prove a substitute for the use of the general reader. The revision of the lectures has been a task attended with no little pleasure, especially since it has given the editor the opportunity for an advance consideration of some of the more recent results, thus materially facilitat- ing investigations which have been in progress at the New York Botanical Garden for some time. So far as the ground has been covered the researches in question corroborate the conclusions of de Vries in all important particulars. The preparation of the manuscript for the printer has consisted chiefly in the adaptation of oral xii Preface by the Editor discussions and demonstrations to a form suitable for permanent record, together with certain other alterations which have been duly submitted to the author. The original phraseology has been preserved as far as pos- sible. The editor wishes to acknowledge material as- sistance in this work from Miss A. M. Vail, Librarian of the New York Botanical Garden. D. T. MaoDougal. New York Botanical Garden, October, 190Jf. PREFACE TO THE SECOND EDITION. The constantly increasing interest in all phases of evo- lution has made necessary the preparation of a second edition of this book within a few months after the first appeared. The opportunity has been used to eliminate typographical errors, and to make alterations in the form of a few sentences for the sake of clearness and smooth- ness. The subject matter remains practically unchanged. An explanatory note has been added on page 575 in order to avoid confusion as to the identity of some of the plants which figure prominently in the experimental investiga- tions in Amsterdam and New York. The portrait which forms the frontispiece is a repro- duction of a photograph taken by Professor F. E. Lloyd and Dr. W. A. Cannon during the visit of Professor de Vries 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 of descent and of natural se- lection. Evolution and adaptation. Elementary species and varieties. Meth- ods of scientific pedigree-culture. B. Elementart Species. II. Elementary species in nature ... 32 Viola tricolor, Draba verna. Primula acaulis, and other examples. Euphorbia Ipecacuanha. Prunus maritima. Taraxa- cum and Hieracium. m. Elementary species of cultivated plants. 63 Beets, apples, pears, clover, flax and coco- nut. IV. Selection of elementary species ... 92 Cereals. Le Couteur. Running out of varieties. Rimpau and Eisler, Avena fa- tua. Meadows. Old Egyptian cereals. Selection by the Romans. Shirreff. Hays. C. Eetrogkade Varieties. V. Characters of retrograde varieties . 121 Seed varieties of pure, not hybrid origin. Differences from elementary species. Latent characters. Eay-florets of com- XIV Contents Lecture Pagk posites.