VU1 PREFACE. 



PEEFACE TO THE THIED EDITION. 



During the last three years the science of Botany has 

 made rapid progress, both in the addition of new facts 

 and in changed points of view. Some of this progress 

 affects Plant Relations, and it is recorded in this third 

 edition so far as it can be without a complete rewriting 

 of the volume. Changes will be found, therefore, in state- 

 ments of fact, in points of view, in terminology, in illus- 

 trations, and also in the addition of new material. 



John M. Coulter. 



The University of Chicago, July, 1904- 



