THE ASH CONSTITUENTS OB^ PLANTS. 



307 



place at the .same rate. AVhen the ash elements are taken up at a 

 more rapid rate than that at which the oroanic matter is formed from 

 the carbonic acid of the air and the nitrog-enous matter of the .soil, the 

 older plants will })e relatively richer in ash than where the reverse is 

 true. When reserve matter is stored up, as when starch is stored in 

 seed or cellulose is formed in wood, then the org-anic matter predom- 

 inates and only a small percentage of ash is present. The same applies 

 to the separate constituents. 



Man}' investigations of the above points have been made, as for 

 example, those of Arendt with oats, of Pierre with wheat, and of 

 Zoiler, KissmiiUer, Dulk, Ramann, Tucker, and others with the leaves 

 of trees. 



Arendt,^ who analyzed oats at four periods of growth, found that 

 the content of silicic acid in the dry matter increased, up to the third 

 period, from 17.46 to 28.62 per cent. The sulphuric acid was at its 

 maximum in the fourth period, and the phosphoric acid in the third 

 period, the percentage of phosphoric acid in the ash increasing from 

 8.93 to 11.21 in that period. The largest amounts of both potash and 

 lime were taken up in the first period, the content of 46.94 per cent 

 of potash and 12.24 of lime in this period decreasing in later periods 

 to 34.48 per cent of potash and 11.59 of lime. 



Pierre ^ obtained similar results with winter wheat. From May 1 to 

 July 25, for example, the ash content of the dried plants fell from 

 7.98 to 3.38 per cent; the percentage of potash in the ash fell from 

 20.46 to 11.72, of Hme from 16.28 to 11.87, and of pho.sphoric acid 

 from 9.12 to 8.08, while the percentage of silicic acid in the ash rose 

 from 32.84 to 54.26. 



In beech leaves, according to Dulk,'* the ash in the dry matter 

 increased during the period from May 26 to November 7 from 4.68 to 

 6.39 per cent. The percentage of potash and phosphoric acid in the 

 ash decreased as the season progressed, while that of lime and silicic 

 acid increased. 



In a similar way Tucker* obtained the following results in a stud}' 

 of the leaves of the plane tree: 



Analyses of the (ish of the leaves of the plane tree. 



^ Landw. Vers. Stat., 1 (1859), p. 65. 



'^Compt. Rend. Acad. Sci. Paris, 68 (1869), p. 1526; Jahresber. Agr. Chem., 1868-69, 

 p. 264. See Wolff's Aschen-Analysen, pt. 2, p. 6. 

 •''Landw. Vers. Stat., 18 (1875), p. 192. 

 * Jour. Landw., 48 (1900), p. 50. 



