578 



TRANSLOCATION 



quent rapid growth or active metabolism is a phenomenon of frequent 

 occurrence and obvious utility. 



Our knowledge of the processes of translocation have largely been obtained 

 by means of the micro-chemical methods first systematically employed by Sachs, 

 who paid attention to the source, destination and character of the translocatory 

 products as well as to the nature of the conducting tissues (cf. Sect. 77). 

 The facts gained by means of ringing experiments are also of importance, 

 although results thus obtained need to be interpreted with the utmost care. 

 Similarly a careful consideration of the internal structural relationships will also 

 be of aid in comprehending translocatory phenomena, for the possibility of 



translocation necessarily involves the existence of 

 purposeful adaptions directed to this end (cf. 

 Sect. 35). A knowledge of the latter is however 

 assumed here \ and it is sufficient to mention 

 that conductive power in a particular direction is 

 increased by the elongation of the conducting 

 elements and by the removal of all obstructing 

 resistances or hindrances, while by means of the 

 continuity and branching of the special con- 

 ducting channels, and by their connexion with 

 the surrounding tissues, the conveyance of food- 

 materials to and from all parts of the plant is 

 assured. The most marked division of labour is 

 exhibited among Phanerogams, and the remarks 

 hitherto made have mainly reference to these. 



Ringing experiments 2 . If a ring of bark is 

 removed from a branch of Sati.v, Ligtistrum &c., 

 at r, and the latter then placed in water or earth 

 up to k-h, after a few weeks only a few feeble 

 roots develop from the smaller lower end (&'), 

 whereas above the point ringed plenty of strong 

 roots are produced and continue to elongate. If, 

 however, only the cortex is removed and the 

 phloem left intact, roots develop equally well and 

 abundantly from the lower end. This is the case 

 also when the experiment is performed with Monocotyledons, or Dicotyledons 

 with bicollateral bundles (Solanaceae, Cucurbitaceae, Asclepiadaceae, Apocynaceae, 

 Cichoraceae :! ) or with medullary bundles. Similar results are also obtained with 



FIG. 67. 



1 See Habeilandt, Physiol. Pflanzenanat., 1896, 2. Aufl., p 263; Strasburger, Leitungsbahnen, 

 1891 ; de Bary, Anat., 1877, and the works here quoted. 



3 Hansteen (Jahrb. f. wiss. Bot, 1860, Bd. n, p. 392) gives numerous experiments, and also 

 mentions the older literature. Cf. also Vochting, Organbildung im Pflanzeureich, 1878 ; 1884, p. 1 14 ; 

 Bot. Zeitung, 1895, p. 84; A. Fischer, Jahrb. f. wiss. Bot., 1891, Bd. xxn, p. 132; Strasburger, 

 Leitungsbahnen, 1891, p. 877; Jost, Bot. Zeitung, 1893, pp. 120, &c. 



1 The three last-named families possess a latex system. 



