PLANT BREEDING by A. L. HAGEDOORN, Ph. D. Preface: Twenty years ago I wrote my Handbook of Animal and Plant Breeding in the Dutch language, and my Animal Breeding, grew out of the first book. The publishers have asked me to write a plant-breeding book as a companion volume to Animal Breeding with a similar scope and in the same style, and the present work is the result. As a young geneticist, I started my career as a plant-breeding consultant with the French firm of de Vilmorin Andrieux et Cie. After the first years I became more and more absorbed in matters of theoretical genetics, and during the last decade 1 have been chiefly concerned with genetics as applied to man kind and to the breeding of domestic animals. I have, how ever, never quite given up plant-breeding matters, although the only kind of practical plant breeding I have been more directly engaged upon has been the production of sugar-beet seed. This book is certainly not a textbook on Genetics, nor does it pretend to be a