THE TRANSLOCATION OF THE ASH CONSTITUENTS 583 



circulation was developed (cf. Sachs, History of Botany, 1882, p. 494). The ascent of 

 ' crude sap ' in the interior of the plant and the descent of ' formed sap ' in the bark 

 after elaboration in the leaves is simply one special example of translocation and is 

 by no means so all important as was subsequently supposed. Hence it arose that 

 in spite of the accumulation of new facts and observations no satisfactory generaliza- 

 tion had been made up to 1850'. This was, however, finally obtained by Sachs' 

 researches \ in which not only were the different processes of translocation taken 

 into account, but also a conscious attempt was made to determine the nature of the 

 different translocatory substances, and the means by which their mobilization and 

 translocation is procured, whereas hitherto it had been customary to speak of 

 a general ' formative sap ' the detailed characteristics of which were comparatively 

 unknown. Sachs also showed that the different translocatory substances might 

 undergo a certain amount of separation from one another in the translocatory 

 channels. The main fundamental principles thus established still hold good, 

 although the sieve-tubes, in opposition to Sachs' view, also function as the most 

 active conductory channels for non-nitrogenous substances, and although, as Pfeffer 3 

 has shown, proleids are translocated in a similar manner to carbohydrates, after 

 undergoing decomposition into amides, &c. Mohl's conclusion that the phloem, 

 and especially the sieve-tubes and elongated phloem elements, were of primary 

 importance for translocation had previously been established by Hanstein's 

 researches 4 . 



SECTION 107. The Translocation of the Ash Constituents. 



These undergo translocation either in the form of inorganic salts or in 

 combination with organic substances, and although in many cases neither 

 the conducting channels nor the translocatory materials have been ascer- 

 tained, there is no doubt that in general the ash constituents follow the 

 same path as organic substances do. The greater part of the ash con- 

 stituents are drawn from the soil in the form of an exceedingly dilute 

 solution, conveyed upwards by the transpiration-current to the living 

 tissues and there utilized. Certain of the elements thus obtained are 

 soon permanently deposited as aplastic materials, whereas many others 

 remain available in some form for further metabolism, or are removed 

 and deposited in storage receptacles, in which all the essential ash con- 

 stituents must necessarily be contained. In many cases, especially in seeds, 



1 Cf. Mohl, Veg. Zelle, 1851, p. 71; Unger, Anat. u. Physjol., 1855, p. 329; Th. Hartig, 

 Pflanzenkeim, 1858, p. 69; Bot. Zeitung, 1862, p. 82. 



2 Sachs, Sitzungsb. d. Wien. Akad., 1859, Bd. xxxvn, p. 57 ; Jahrb. f. wiss. Bot., 1863, Bd. in, 

 p. 183; Flora, 1863, p. 32. 



3 Pfeffer, Jahrb. f. wiss. Bot., 1872, Bd. vill, p. 538. 



4 Mohl, Bot. Zeitung, 1885, p. 897; Hanslein, Jahrb. f. wiss. Bot., 1860, Bd. II, p. 392. The 

 older literatnre is here quoted. 



