SCIENCE IN AGRICULTURE. 445 



soil, as it was formed by the decomposition of tlie rocks 

 whether changed or not from its place by dihivial or alluvial 

 action. I now proceed to speak of the modification which it 

 has experienced from the decay of vegetable and animal sub- 

 stances on the surface, forming what is called mould. 



Originally the earth had none of this mould on its surface. 

 The first races of vegetables derived their nourishment from a 

 purely mineral soil, from water, and the air. From this soil 

 they obtained their potash, their silex, their magnesia, their 

 lime, their phosphorous, their ammonia. From the water they 

 obtained their hydrogen. From the air they derived their car- 

 bon, existing in a free state or connected with water. Thus 

 they grew, and when they died and decayed, the elements which 

 composed them were united to the mineral soil to alTord nour- 

 ishment for the next generation of vegetables. Animals, sub- 

 sisting as they do directly or indirectly upon vegetables, take 

 the elements which compose their bodies chiefly from their food, 

 and, in their life and in their death, bestow these elements on 

 the soil. In this way provision is made by the Creator for 

 greatly enriching the earth. 



The difi"erence between the mould on the surface and the soil 

 below is, that mould contains decayed vegetable and animal 

 matter. The quality of this matter must depend on the quan- 

 tity of the vegetable and animal substances of which it is 

 f )rmed. For instance, that which is formed by the decay of ma- 

 ple wood must differ from that which is formed by the decay of 

 pine wood. 



Now one other general fact, or law, or principle, discovered 

 by science is, that in some soils, vegetable and animal sub- 

 stances, if buried so far below the surface that the air docs not 

 get access to them, remain organic, and they are not converted 

 into a form in which they can nourish plants. 



Another general principle or fact discovered by science, is 

 that decayed animal and vegetable matter in the soil, is nearly 

 insoluble in cold water, and, therefore, is not carried off by the 

 rain, and does Bot sink into the earth. 



Still another general principle or fact discovered by science is, 

 ^ that this decayed animal and vegetable matter is liable to be 



