INTEODUCTION. 27 



heat, light, and otlier agencies, is annulled or overcome, so 

 that compounds resolve themselves into simpler combina- 

 tions or into their elements. Chemistry is the science of 

 composition and decomposition ; it conside^rs the laws and 

 results of affinity. 



HI.— Physiology, which unfolds the laws of the devel- 

 opment, sustenance, and death, of living organisms. 



When we assert that the object of agriculture is to de- 

 velop from the soil the greatest possible amount of cer- 

 tain kinds of vegetable and animal produce at the least 

 cost, we suggest the topics which . are most important for 

 the agriculturist to understand. 



The farmer deals with the plant, with the soil, with ma- 

 nures. These stand in close relations to each other, and 

 to the atmosphere which constantly surrounds and acts 

 upon them. How the plant grows, — the conditions under 

 which it flourishes or suffers detriment, — the materials 

 of whicb it is made, — the mode of its construction and 

 organization, — how it feeds upon the soil and air, — how it 

 serves as food to animals, — how the air, soil, plant, and 

 animal, stand related to each other in a perpetual round 

 of the most beautiful and wonderful transformations, — 

 these are some of the grand questions that come before 

 us ; and they are not less interesting to the philosopher 

 or man of culture, than important to the farmer who 

 depends upon their practical solution for his comfort ; or 

 to the statesman, who regards them in their bearings 

 upon the weightiest of political considerations. 



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