SECTION FIRST. 



CHAPTER I. 



INTRODUCTION. 



THE object of cultivating the soil is to raise from it 

 a crop of plants. In order to cultivate with economy, 

 we must raise the largest possible quantity with the 

 least expense, and without permanent injury to the 

 soil. 



Before this can be done we must study the char- 

 acter of plants, and learn their exact composition. 

 They are not created by a mysterious power, they 

 are merely made up of matters already in existence. 

 They take up water containing food and other mat- 

 ters, and discharge from their roots, or their leaves, 

 or deposit within their pores, those substances that 

 are not required for their growth. It is necessary 

 for us to know what kind of matter is required as 

 food for Uie plant, and whence it is to be obtained ; 

 this we can learn only through such means as shall 

 separate the elements of which plants are composed ; 



