52 



constituent which is present in smallest proportion. The 

 Minimum Theory applied to phosphoric acid. The stores 

 of phosphoric acid available. Guano. Animal refuse. 

 Bones. Coprolites. A conservancy department for the 

 animal kingdom necessary. The assimilation by the 

 plant of its inorganic parts. Endosmose. The transfor- 

 mation of the sap in the leaves. Prince Salm Horstmar's 

 experiments proving the relative necessity of each of the 

 mineral plant constituents. The absence of a single one 

 . in the soil affects the whole organism of the plant. The 

 division of plants into groups according to their principal 

 inorganic constituents. The different kinds of soils best 

 suited for the different kinds of plants. 



THOUGH, when compared with the large bulk of 

 the organic parts of a vegetable compound, the 

 inorganic parts constitute a very small percentage 

 amounting, on the average, to only 5 per cent, of 

 the whole yet the influence they exert upon 

 vegetable life is most important. The functions 

 they have to fulfil in assisting in the transfor- 

 mation and transmission of the various elements of 

 organic life, are unhappily but imperfectly known, 

 and we must fain be content with such ideas and 

 theories as experiments and observations lead us 

 to deduce ; but even then it is sometimes extremely 

 difficult to express our ideas of certain processes 

 in suitable and comprehensive language. 



By the influence of acids, woody fibre can 

 be converted into starch, and starch into sugar ; 

 but as to the nature and causes of the chemical 

 transformation of their elements, chemists have not 

 as yet agreed in fact, it must be confessed that we 



