Inorganic Constituents of Plants. 601 



De Saussure available for the determination of the functions 

 fulfilled in plants by inorganic acids and bases. 



Berthier* has also made a considerable number of analyses 

 of the ashes of various woods; his only object however was 

 to ascertain, if possible, what effects the ashes of the wood used 

 as fuel in metallurgy would have upon those processes. 



Berthier found by a comparison of his carefully obtained 

 analytical results, that the nature of the ash depended to some 

 extent upon the properties of soil ; he observed that the com- 

 positionof the ashes of the same kind of wood grown on different 

 soils, differed considerably ; he showed also that the ashes of 

 different kinds of plants grown upon the same soil were dis- 

 similar, and that plants which are identical or allied in kind, 

 when grown upon the same soil, yield ashes, the compositions 

 of which are also either allied or identical. Finally, Wieg- 

 mann and PolstorfFf, by ascertaining the quantity of ashes of 

 plants which have vegetated in sand and in artificial mould, 

 have clearly shown that the increase of plants, their growth, 

 and full development are inseparably connected with the or- 

 ganic materials contained in the earth, and that plants will not 

 perfect their seeds if the earth is deficient in phosphates, &c. 

 All recorded observations clearly show that plants take up 

 indiscriminately the soluble mineral constituents presented to 

 them by the soil ; and the results of ash-analyses as distinctly 

 prove, that for the purpose of assimilation by their different 

 parts and organs, they make a selection from those constitu- 

 ents; that the organism of vegetables, like that of animals, 

 takes up and retains those substances which it requires. 



It follows from what has been said, that in the analysis of 

 ashes, a number of substances will be found which have not 

 entered into the composition of any organ of the plant, sub- 

 stances which have been dissolved by the juices of the plant; 

 and, since we have no means of safely separating them for the 

 purposes of analysis, they will remain after the ignition mixed 

 with the assimilable and assimilated mineral constituents of 

 the plant. 



Nature has provided in the seeds of plants, as in the eggs 

 and milk of animals, all the substances which are necessary 

 for the development of the young individual, so long as it is 

 itself incapable of seeking sustenance externally. In the ashes 

 of seeds we shall find therefore treasured up, and almost pure, 

 the indispensable mineral food of the plants. 



The examinations hitherto made of the ashes of seeds indi- 

 cate that those of the Cerealia, the Legiwiinos^^, the Cruci/env, 



* Aim. de Chbnie et de Phys. xxxii. p. 240. 



-f- Ueber die unorgan. Bestandtkcilc der PJlanzen ; gelriJiite Preisschrif't. 

 Braunschweiff, 1842. 



