INTRODUCTION. 27 
heat, light, and other 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 considers the laws and 
results of aflinity. 
IiI.—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 which 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. 
