INTRODUCTION 207 



therapeutics and diseases, with a wealth of solid information that has 

 hardly ever been utilized by our science. 



It is hoped that these researches will chiefly appeal to botanists 

 and to students of human civilization; but, as it can hardly be expected 

 that the individual botanist will be equally interested in the history 

 of every plant here presented, each subject is treated as a unit and 

 as an independent essay, so that any one, according to his inclination 

 and choice, may approach any chapter he desires. Repetitions have 

 therefore not been shunned, and cross-references are liberally inter- 

 spersed; it should be borne in mind, however, that my object is not 

 to outline merely the history of this or that plant, but what I wish to 

 present is a synthetic and comprehensive picture of a great and unique 

 plant-migration in the sense of a cultural movement, and simultane- 

 ously an attempt to determine the Iranian stratum in the structure of 

 Chinese civilization. It is not easy to combine botanical, oriental, 

 philological, and historical knowledge, but no pains have been spared 

 to render justice to both the botanical and the historical side of each 

 problem. All data have been sifted critically, whether they come 

 from Chinese, Japanese, Indian, Persian, Arabic, or classical sources, 

 and in no instance have I depended on a second-hand or dogmatic 

 statement. The various criticisms of A. de Candolle, A. Engler, E. 

 Bretschneider, and other eminent authorities, arise from the critical 

 attitude toward the subject, and merely aim at the furtherance of the 

 cause. 



I wish to express my thanks to Dr. Tanaka TyOzaburO in the 

 Bureau of Plant Industry of the Department of Agriculture, Washing- 

 ton, for having kindly prepared a translation of the notices on the 

 grape-vine and the walnut from Japanese sources, which are appended 

 to the chapters on the history of these plants. The manuscript of this 

 publication was completed in April, 1918. 



The generosity of Mrs. T. B. Blackstone and Mr. Charles R. 

 Crane in contributing a fund toward the printing of this volume is 

 gratefully acknowledged. 



