ujlLliRARY 



^ 



PHYTOHORMONES ^^^^ 



i/ m VV 



CHAPTER I 

 INTRODUCTION 



The field of plant hormones is perhaps now at the stage 

 of its most rapid development. The number of facts is be- 

 coming so large, and their distribution through the literature 

 so scattered, that there is a danger of losing sight of the 

 general trend. We shall attempt not so much to give a 

 detailed historical account as, rather, to present the field 

 from the point of view of workers in it. Where matters of 

 hypothesis are concerned, our personal views will necessarily 

 be emphasized, but opposing views will be given an oppor- 

 tunity for the reader's consideration. In matters of fact, as 

 also in regard to credit and priority, every attempt will be 

 made to give as fair and accurate an account as possible, 

 both of the experiments and of the concepts of the different 

 workers. For the sake of completeness many new experi- 

 ments have been included. These are designated as u (un- 

 published). Some idea of the amount of work which has 

 been done in this field may be gained from the statement 

 that the contents of this book are based on actual measure- 

 ments of the responses of about one million plants. The 

 growing interest in the field is exemplified by the fact that 

 the bibliography includes references to 77 pubhcations dated 

 1936. Since equally detailed and critical treatment cannot 

 be accorded to all of this material, we have naturally laid 

 emphasis on w^hat appears to be the most important work. 



A. Outline of the Book 

 Our re\dew will deal only with the hormones of higher 

 plants. We shall first trace the development of the leading 



