PREFACE 



The extension of knowledge in all departments of botany 

 during the last few years has widened the application of the prin- 

 ciples of physiology, and altered the relative importance of many 

 phases of the subject. The most notable development consists 

 of the universal recognition of the underlying and basal impor- 

 tance of the irritability of the organism ; " that there is no vital 

 process which is uninfluenced by stimuli, which permit, cause, 

 restrict, or regulate the particular action in question." A second 

 conception of no less importance is that of the intricate correlation 

 existing between all of the activities of the vegetal organism, and 

 the reciprocal interaction of all physiological stimuli. 



The arrangement of the subject in the following pages is an 

 effort to place before the student a method by which a working 

 knowledge of the physiological complex of the plant may be ac- 

 quired. The disposition of the subject matter entailed by this 

 treatment consists, briefly stated, in the study of the particular 

 functions and properties of the organism, in connection with the 

 agencies and forces which influence or initiate them, and a con- 

 sideration of the general processes of plant life. To this end the 

 first portion of the book, inclusive of chapters I.-VIL, is devoted 

 chiefly to the special forms of irritability exhibited by typical 

 organisms, and the second part is taken up with a more critical 

 consideration of the broader phases of the activity of the plant : 

 a treatment of the subject well adapted to the convenience of the 

 independent worker, and to the exigencies of instruction. 



A discussion of the principles of the subject is interwoven with 

 the directions for practical demonstrations in order to afford means 

 of interpretation of the experimental results secured : such dis- 

 cussion is naturally limited to the statement of prevalent generali- 

 zations in greater part ; the space at command does not permit a 



