PREFACE ix 



background of information increases in subsequent chapters, the inter- 

 relations discussed become more intricate and the student is expected 

 to participate more and more inteUigently in discussions involving a 

 knowledge of structural systems of cells or of whole plants, of sequences 

 of events in the development of a plant or of the whole life cycle, of 

 the intimate relations of chromosomes and hereditary factors, of the 

 interrelations of physiological processes and development, of physi- 

 ological processes and environment, or of a combination of all these 

 phenomena. 



Material from all the artificial subdivisions of botany is included 

 not because we intended to survey the entire field, but because the 

 synthesis of material from all phases of botany is necessary to give a 

 student a general perspective of his relations to his plant environment. 

 In keeping with the scientific attitude, throughout all this diversitv 

 we have persistentlv tried to maintain a terminology and phraseologv 

 consistent with the outlook of special students in the various fields of 

 botany. 



