Species and Varieties, Their Origin by Mutation

by Hugo de Vries

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 scientific pedigree-culture.

B. ELEMENTARY SPECIES.

II. Elementary species in nature. 32