Introduction 1 1 



mind that while both the brief and the extensive standard 

 works are important, the subject is one which, through its 

 diverse relationships, encourages breadth of preparation 

 and of application ; so that frequently physiological texts 

 alone are insufficient. Any standard text is in large part a 

 logical arrangement and correlation of the facts of many 

 separate papers or monographs ; and the detailed data 

 respecting any phenomenon should be sought in the spe- 

 cial paper. 



The rapid strides which have been made in scientific 

 agriculture and horticulture, especially in plant chemistry, 

 soils, and intensified production, have developed a great 

 array of interesting phenomena. This has given a decided 

 impetus to physiological study. Often, unfortunately, the 

 agriculturist has been compelled to go forward without due 

 knowledge of physiology in the interpretation of his results, 

 but this is no excuse for the neglect of the large amount of 

 valuable and sound work which has been done. 



Again, it should be further emphasized that many phys- 

 iological phenomena are only properly understood when 

 they are viewed in the light of physical and chemical the- 

 ory, and it is frequently necessary that the student who is 

 encouraged to go further shall turn to the sources of in- 

 formation in these fundamental sciences. 



8. Physiology and other sciences. - The aim of plant 

 physiology is a definite one, like that of other sciences; it 

 is ultimately to obtain precise information concerning all 

 those factors and forces which are operative within or 

 through the living plant. Facts are derived and laws es- 

 tablished in exactly the same manner as in other sciences. 

 It does not stand apart from physics and chemistry, but 



