PLANT-BREEDING 



COMMENTS ON THE EXPERIMENTS OF NILSSON AND BURBANK 



CONTENTS 



I. Evolution and Mutation ..... i 



II. The Discovery of the Elementary Species of Agri- 

 cultural Plants by Hjalmar Nilsson. 



A. Different Principles in the Breeding of Cereals . . 29 



B. The Swedish Agricultural Experiment Station at Svalof 48 



C. The Svalof Method of Producing Improved Races . 67 



D. A Criticism of the Method of Continuous Selection . 90 



III. On Corn-Breeding ....... 107 



IV. The Production of Horticultural Novelties by 



Luther Burbank. 



A. Methods and Material i59 



B. New Varieties in Fruits and Flowers . . .178 



C. Hybridization and Selection ..... 202 



D. Mutations in Horticulture . . . . .221 



V. The Association of Characters in Plant-Breeding. 



A. Association of Characters in Nature . . -237 



B. Correlations in Agricultural Breeding . . -255 



C. A Methodical Study of Correlations . . .271 



D. Correlations in Fluctuating Variability . . . 289 



E. Unit-Characters 309 



VI. The Geographical Distribution of Plants . . 333 

 Index 353 



