Preface ix 



whose source is acknowledged (viz., figures 81, 85, 107, 168, 175), 

 have been re-drawn for this work by one of my students, Miss 

 Bertha Bodwell, now Mrs. Richard Potter. The remainder of the 

 pictures, somewhat over one-half of those^in the book, are new. 

 Several have been made by students of mine: figures 18 to 23, 

 with 76 and 84 by Miss Bodwell: figures 27, 56, 57, 132, illustrat- 

 ing physiological apparatus, with 126-7-8, showing phases of 

 growth, by Miss Margaret Sargent: figures 103, 104, parts of a 

 series representing the development of representative plants, by 

 Miss Ruth Huntington, now Mrs. Max Brodel: figure 87 by Miss 

 Stella Streeter: figure 133 by Miss Hope Sherman: while the fine 

 graphs of figures 70 and 123 were worked out from the original 

 materials as well as drawn by Miss Marion Pleasants. The photo- 

 graph of figure 26 was given me by another student, Miss Anne 

 Barrows, now Mrs. Walter Seelye. The elaborate and exact 

 drawing of root tissues forming figure 53 was made by my col- 

 league, Dr. F. Grace Smith, Associate Professor of Botany in 

 Smith College, while the markedly original and very satisfactory 

 series of generalized drawings in illustration of the principal 

 physiological processes, embodied on the colored Plate I, and in 

 the multiple figures 54, 66, 139, together with the figures 30 and 

 99, were specially drawn for this book by another of my associates, 

 Miss Helen A. Choate, Instructor in Botany in Smith College. 

 To all of these willing and efficient collaborators I desire here to 

 express my indebtedness, and my grateful thanks. The remainder 

 of the illustrations, including the new photographs and diagrams, 

 are productions of my own. 



But the greatest of my obligations is to Miss Choate, who has 

 read both manuscript and proofs in a critical spirit no less militant 

 because friendly. She has not been concerned so much with the 

 scientific aspects of the chapters as with their exposition, rep- 

 resenting in this the rights of the reader, for whose benefit she 

 has curbed much exuberance of expression, and eliminated mam r 

 an obscurity and inconsistency. That some of these faults re- 



