CHAPTER X 



TRANSLOCATION 



SECTION 106. Translocation of Organic Food-substances. 



WHENEVER food-materials are, as is often the case, utilized or con- 

 sumed in parts far removed from those where they are produced or 

 absorbed, a transference from the one region to the other becomes neces- 

 sary. Thus the ash constituents absorbed by the roots of a tree from the 

 soil must be transferred to the foliage-leaves even when these are situated 



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at its summit many yards from the ground, whereas the products of 

 photosynthetic assimilation pass downwards to the roots, which are pro- 

 vided in this manner with organic food. Similarly the nutriment absorbed 

 by a fungus mycelium from the substratum must be transferred in sufficient 

 abundance to nourish the erect sporangiferous or sterile sub-aerial hyphae, 

 no matter whether these are multi- or uni-cellular filaments. Indeed 

 the metabolism of every individual cell is unavoidably associated with an 

 absorption and excretion of nutritive substances and metabolic products, 

 which are transferred from one region of the cell to another after their 

 absorption or before their excretion. 



We must therefore deal with the translocatory channels, the nature 

 of the translocatory substances, and the means by which the transference of 

 material from one part to another is induced, rendered possible, performed 

 and regulated. The main principles involved have already been discussed 

 (Chap. IV, cf. also Sect. 93), and it only requires a simultaneous considera- 

 tion of the properties, structural relationships, and vital activities of the parts 

 involved cither to render possible a clear comprehension of the manifold 

 phenomena of translocation, or to provide a preliminary explanation where 

 our knowledge is as yet incomplete. It has already been mentioned why 

 various metamorphoses commonly accompany translocation, and the im- 

 portance of these changes has been previously discussed, while it has also 

 been shown how and why translocation is regulated by the consumption, 

 demand and supply. Hence the processes of translocation are modified 

 during the progress of development, and are also influenced by the 

 external conditions. Thus reserve materials accumulate at certain periods, 



