24 INTRODUCTION. 



ence is not so immediately under the control of the agricul- 

 turist as any of the preceding agents. 



4. Elcctricitij even more readily yields its agency to the 

 skill of man. The electrical character of the soil may readily 

 be determined. It may even be changed by artificial appli- 

 ances, and hence what was barren and worthless, may be 

 rendered fruitful. But as these latter forces will receive par- 

 ticular attention, as to their influence on vegetation, in the 

 body of this work, it is unnecessary to enter into any further 

 specification of their agency. 



The chemical forces above enumerated, in their influence 

 upon vegetables themselves, are in subordination to another 

 force, the living power ; and hence we must resort to 

 vegetable physiology {or further aid, in explaining the pro- 

 cesses of vegetation, and in pointing out the conditions for 

 successful practice in agriculture. 



III. Botany furnishes us with principles more directly ap- 

 plicable to agriculture, as a science, than either of the preced- 

 ing sciences. In fact, one branch of this science, the living 

 functions of plants, or Biology, including the conditions of 

 life, and all the near or remote influences which act upon the 

 vital forces, and tend to quicken or destroy them, constitutes 

 of itself the whole science of agriculture. Such a view, how- 

 ever, might properly bring in chemistry, as a modifying force, 

 as well as mineralogy and geology. In a more restricted 

 sense, botany offers the following aids : 



1. It explains the structure of the various organs of plants, 

 by which we are made acquainted with the means of introduc- 

 ing and disposing of the matter by which they are nourished. 



3. It determines the habits of each species of plant, by 

 which we are enabled to adapt the crop to the climate and soil. 



3. It points out what plants require as the condition of 

 their most perfect growth, and how to obtain the best quality 

 of their products. It enables us also to obtain the best kinds 

 or species of plants, to ascertain their mode of propagation. 



