Plant-breeding; being six lectures upon the amelioration of domestic plants

Front matter

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Preface

There is no subject associated with the care of plants respecting which there is so much misapprehension and imperfect knowledge, as that of the origination of new forms. Most of the scattered writing touching it treats the subject as if all our knowledge of the matter were and must be derived wholly from experiment. It therefore recites examples of how this and that new form has come to be, and has made little attempt to discover the fundamental causes of the genesis of the novelties. Horticulturists commonly look upon each novelty as an isolated fact, whilst we ought to regard each one as but an expression of some law of the variation of plants. It is the common notion, too, to consider any type of plant to- be essentially a fixed entity, and to regard any marked departure from

the type as a phenomenon rather more to be

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wondered at than to be explained. It is evident, however, that one cannot understand the production of new varieties until he has grasped some of the fundamental principles of the onward progression of the vegetable kingdom. Any attempt, therefore, to explain the origin of garden varieties, and the methods of producing them, must be at the same time a contribution to the literature of the philosophy of organic evolution.

I do not know of any explicit and sustained attempt to account for the evolution of all garden forms, and I have therefore brought together in this volume the subject-matter of various lectures which I have been in the habit of giving before my students. The first and third lectures were newly elaborated the present summer for two addresses before the class in biology which came together at the University of Pennsylvania, under the auspices of the American Society for the Extension of University Teaching. The second lecture was first presented before the Massachusetts State Board of Agriculture, in Boston, December 1, 1891. In April, 1892, it was republished, with a bibli-

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ography of the subject, by the Rural Publishing Co., under the title, " Cross-Breeding and Hybridizing." This publication is now out of print. I have made no attempt to collect lists or catalogues of varieties, but have endeavored to make very brief statements of some of the underlying principles of the amelioration of plants, with only sufficient examples to fix them in the mind.

I hope that teachers of horticulture and botany may find the book useful in their classes. When it is necessary to abridge the instruction or to present it to untrained students, only Lectures III. and V. may be used, for these contain the matters of greatest demonstrative importance.

L. H. Bailey.

Cornell University, Ithaca, N.Y., September 1, 1895.

Preface To Third Edition

In the eight years since this book was sent to the printer, there have been great changes in our attitude toward most of the fundamental questions that are discussed in its pages. In fact, these years may be said to have marked a transition between two habits of thought in respect to the means of the evolution of plants, — from the points of view held by Darwin and the older writers to those arising from definite experimental studies in species and varieties. We have not given up the old nor wholly accepted the new, but it is certain that our outlook is shifting. So far as practical plant-breeding is involved, the changing attitude is concerned chiefly with discussions of the nature of varieties and the nature of hybridization.

The chief practical result of the discussion of

the nature of varieties is a re-defining of what a

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variety is, whereby we have come to recognize the fact, more clearly than heretofore, that not all differences in plants are of equal importance or significance.

The practical result of the discussions of hybridization is the growing belief that the offspring of hybridization follow definite laws. This statement seems to be wholly at issue with the tenor of Lecture II. ; but the apparent contradictions are largely such as follow from two sets of definitions of the ideas of " variety" and "hybrid." It must also be remembered that even if hybridization follows definite laws, the practical results are commonly so modified and obscured by interfering circumstances that safe predictions usually cannot be made. I had once thought of rewriting Lecture II., but on going over it again I found that the chief change that I should desire now to make would be a rephrasing in order to conform it to the method of current discussions. Moreover, we are not yet ready to make very positive discussions from the newer studies. The time cannot be far distant when the subject of plant-breeding will be rewritten from a new point of view. In the meantime, I hope that the new matter in

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Lecture IV. may set the reader straight on some of the newer problems.

The first issue of this book was made late in 1895. The second edition was made early in 1902. In the meantime it had been twice reprinted. By an inadvertence, the second edition was not so marked on the title-page. In that edition the changes in the text were few. The only very important departure was the publication of a bibliography. This bibliography had appeared with my paper on " Cross-Breeding and Hybridizing," which was published in 1892 as one of the Rural Library Series. It was purposely confined to such literature as English-speaking horticulturists would be most likely to find. The edition was soon exhausted, and many requests for this bibliography decided me to extend and republish it. In the present edition I have added somewhat to this bibliography (to the close of 1902), and have made some changes in the text ; but the leading change is the substituting of new matter for the old Lecture IV.

L. H. Bailey

Cornell University, Ithaca, N.Y., September 1, 1903.

Contents

LECTURE L

The Fact and Philosophy of Variation • .

I. The Fact of Individuality .... The seed-individual.