Preface


agricultural history to be found, supplied much of the material
for this book. Supplementary information was found in the
manuscript archives of the Patent Office and the Departments
of Agriculture, Navy, and State. I also consulted sources in the
Library of Congress. Other bibliographical references will be
found at the end of each chapter.
 I wish to acknowledge here the assistance I received from
Dr. W. P. Webb, chairman of my supervising committee for
the doctoral degree, and other members of the committee at the
University of Texas who gave much time to reading and helpful
criticism in the first preparation of this work as a doctoral
dissertation. Dr. Wood Gray, George Washington University,
and Mr. B. Y. Morrison of the Bureau of Plant Industry gave
valuable guidance and useful information. I also frequently
consulted Dr. Everett E. Edwards of the Bureau of Agricultural
Economics.
 Acknowledgements for criticism, suggestions, and information
also are due to Mr. Marshall Townsend, Mr. Merritt Bailey,
Dr. Earle D. Ross, and Dr. Max M. Hoover of Iowa State
College, and to Mr. C. O. Erlanson, Assistant Chief of the Divi-
sion of Plant Exploration and Introduction. I am grateful to
Dr. David G. Fairchild for permission to use several photographs
he made; and I am indebted to my wife for her assistance in
proofreading and invaluable cooperation.


 NELSON KLOSE


February, 1950