INTRODUCTION. . 11 



will induce the establishment of Agricultural 

 Colleges, where young men, after having 

 completed their education, as far as the rou- 

 tine and practical information necessarily con- 

 nected with farming is concerned, may spend 

 a few months in the acquisition of such 

 chemical knowledge for the analysis of the 

 various soils and products, as will prove bene- 

 licial to themselves as well as the community 

 at large. 



In the following pages it is intended to 

 explain, as far as our knowledge already ex- 

 tends, the manner in which plants assimilate 

 their food and the sources of its supply. To 

 do this, some preliminary knowledge is neces- 

 sary ; it is therefore proposed to consider the 

 subjects in the following order. 



First — The structure and functions of the 

 different parts of plants. 



Second — The general attributes of the soil. 



Third — The simple bodies forming the 

 structure of the plant, the sources from which 

 they are obtained, and the manner in which 

 they are assimilated. 



And lastly — The specific action of the va- 

 rious manures now in use. 



In considering these subjects, it will be as- 

 sumed that the reader has no previous know- 

 ledge of the question. No apology is therefore 

 offered for the elementary character which each 

 chapter will exhibit. It has been the desire of 

 the writer to explain every circumstance as 

 fully as possible, and although the use of tech- 

 nical terms is necessarily unavoidable in such a 



