44 
ELEMENT* OF AGRICULTURE. 
cedingJessons; but it must also, united with 4 the miners 
logical elements, contain elements of organic origin; foi 
these last play a very active part in vegetation. 
49. If we examine closely what passes in nature, we 
will perceive that all organized bodies are continually 
changing in shape, until finally, the vital principle ceasing 
to exi st in them, they perish and decompose. It is these 
decomposed bodies that we put on the land to satisfy the 
wants of plants, which, after having served as food to man 
and animals, become the sourcS of a new vegetation. 
50. This alternate and continual change has caused it to 
be said that vegetation is the source of reproduction, and 
in truth : “ No plants, no animals ; no animals, no manure; 
no manure, no cultivation.” As we perceive, bodies are 
not annihilated ; they are only continually assuming dif- 
ferent forms. The earth may be considered as a mediator 
between life and death, as it receives from disorganized 
vegetables elements that it gives back to a new organic life. 
51. A soil is the richer, and consequently the more pro¬ 
ductive, as it contains more organic remains. On the other 
hand, as we have some crops that are more exacting than 
others as regards the quantity of nutritive elements that 
they require, it follows, that the farmer should take the 
least exhausting crops from the least fertile land; for in 
rational agriculture we can never exact from a soil more 
than we give it, or more than its nature permits it to fur¬ 
nish. 
52. The soil is not always exhausted by the crops that 
it yields; for such crops leave remains that decompose in 
the soil. These remains are the leaves, stems, and roots 
of the plant. The more numerous they are, the less is the 
soil injured ; and it may be (as with clover), that it has 
lost none of its value ; so that, to obtain other products, it 
is not necessary to add to the organic remains already 
within it. But the farmer ought, in this case, to be 
