EDITOE'S PEEFACE. 



IN the following work Baron Liebig has given to the 

 public his mature views on agriculture, after sixteen 

 years of experiments and reflection. The fundamental 

 basis of the work is still the so-called Mineral Theory, 

 which holds that the food of plants is of inorganic nature, 

 and that every one of the elements of food must be present 

 in a soil for the proper growth of a plant. The discovery 

 of the remarkable power of absorption possessed by arable 

 soils has necessarily led to a modification of the views re- 

 garding the mode in which plants take up their food from 

 the soil. As the food of plants cannot exist for any length 

 of time in solution in soils, it is clear that there cannot be 

 a circulation of such solution towards the roots, but the 

 latter must go in search of food. Hence the great impor- 

 tance of studying the ramification of the roots of plants, and 

 the mode of growth of the different classes of plants culti- 

 vated by man. The first chapter is devoted to the consid- 

 eretion of the growth of plants, of the formation of their 

 roots, and of their power of selecting food, and the part 

 played by the mineral matters which are absorbed. 



If the food of plants is not in solution in the ground, 

 we can conceive that those portions of the soil traversed by 

 the numerous root ramifications will be more or less ex- 

 hausted of food elements, whilst the immediate neighbour- 



All 



