Species and Varieties, Their Origin by Mutation | Page 2

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 Morgan 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 Botanical Garden for their
painstaking work in the preparation of the manuscript for the press. Dr.
MacDougal, by [viii] his publications, has introduced my results to his
American colleagues, and moreover by his cultures of the mutative
species of the great evening-primrose has contributed additional proof
of the validity of my views, which will go far to obviate the difficulties,
which are still in the way of a more universal acceptation of the theory
of mutation. My work claims to be in full accord 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 scientific 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.
[ix]
PREFACE BY THE EDITOR
PROFESSOR 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 result 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 investigation 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 facilitating 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]
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
possible. The editor wishes to acknowledge material assistance in this
work from Miss A.M. Vail, Librarian of the New York Botanical
Garden.
D.T. MacDougal. New York Botanical Garden, October, 1904.
PREFACE TO THE SECOND EDITION.
THE constantly increasing interest in all phases of evolution 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 smoothness. 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
investigations in Amsterdam and New York.
The portrait which forms the frontispiece is a reproduction 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 selection. Evolution and adaptation.
Elementary species and varieties. Methods of