146 STATES OF THE RIVER PLATE. 



life. These elements constitute the mineral base of every- 

 thing that has life, development, and organism : from 

 the humblest plant to the masterpiece of organism, man, 

 there can be nothing without them. It is the combina- 

 tion of these organic mineral substances with gaseous 

 elements which forms organic or living things; and this 

 combination is effected under a 'power' which is arbi- 

 trarily styled ' vital force,' or ' vital action,' and which 

 comprehends every defined and undefined power from 

 sunlight to electricity, culminating in the 'vsill' of the 

 Creator. 



These minerals are of two main divisions, or, more 

 properly speaking, three — acid, alkali, and metallic — 

 and consist of phosphoric acid, sulphuric acid, carbonic 

 acid, potash, soda, lime, magnesia, sihca, and iron. The 

 presence in the soil of aU these is absolutely requisite, 

 otherwise vegetation could not exist on it. Vegetation is 

 more or less luxuriant or scanty according as there is less 

 or more of these in the soil in an available form, and the 

 character or class of natural herbage is determined by 

 the relative proportions in which they exist. This is 

 exemplified by the growth of rushes and sedgy herbage 

 on low wet silicious clay, or clay lands in which there is 

 always present a large quantity of free siHcic acid, so 

 considerable a quantity of which (silica) enters into the 

 composition of sedgy herbage, and by the permanence of 

 sainfoin, clovers, and the like, on soils containing much 

 lime ; this element being a large constituent of the many 

 varieties of this class or order of plants. 



