TRANSLOCATION BY DIOSMOSIS. 363 



equilibrium, in accordance with the diosmotic conditions just given, and then all 

 further movements of dififusion cease. If, for example, a cell is able to take up sugar 

 by endosmose from Its environment, the absorption ceases so soon as an equal con- 

 centration occurs within and outside the cell, or even earlier. If, however, the sugar 

 which enters into the cell is made use of, to form starch for example, then so long 

 as the formation of starch continues more sugar will be able continually to pass into 

 the same cell ; and it is obvious that the chemical metamorphosis of the diosmotic 

 body here prevents the establishment of an equilibrium of diffusion, and contributes 

 to the continual transport of larger quantities into the cell, which thus behaves towards 

 its saccharine environment as a centre of attraction. Something very similar will 

 happen if proteid-forming substances diffuse into a cell, and are there employed in 

 the formation of crystalloids. In like manner it is obvious that when starch-grains 

 are transformed into sugar in a cell, and neighbouring cells take up the sugar by 

 diosmosis, equilibrium can only be established when the formation of sugar ceases in 

 the cell containing starch ; or, in other words, a cell in which a soluble substance 

 arises behaves in diffusion as a centre of repulsion. 



This view may be also extended to whole aggregates of tissues and organs, 

 and at the same time we obtain from it the reason why chemical metamorphoses of 

 the plastic matters are so generally connected with their transport. To give a few 

 examples only. — Starch is assimilated in the leaves of the Beet : in the petioles it is 

 found again in the form of glucose (i. e. a sugar which reduces cuprous oxide). This 

 glucose now enters the growing and swelling root, and is transformed into cane-sugar 

 in its parenchyma. As each particle of glucose, which evidently passes from the 

 petioles and enters the root, is transformed into cane-sugar, it acts, according to the 

 laws of diffusion, as if it had been annihilated, and so long as the transforma- 

 tion of glucose into cane-sugar takes place in the root, fresh glucose can continually 

 flow in. In this manner, in spite of the influx, the root goes on behaving like a 

 body destitute of glucose, and acts on the product of assimilation of the leaves as a 

 centre of attraction. The formation of starch in the growing tubers of the potato 

 plant is another case in point; here also the product of assimilation of the leaves 

 is carried through the stem into the tubers in the form of glucose ; in these, however, 

 it disappears as such, being employed for the formation of starch. An equilibrium 

 of diffusion does not take place, therefore, so far as the glucose is concerned; it 

 streams continually into the tubers, because it is there continually being converted 

 into starch. Chemical metamorphosis acts in the same way in the using up of 

 reserve-materials in growing seedlings. If the reservoirs of reserve-materials contain 

 cane-sugar, inulin, or fat, glucose arises in the seedlings at the commencement of 

 growth, at the expense of these materials, and from this starch-grains, which are 

 then finally again dissolved and employed for the growth of cell-walls. To mention 

 one other example only, the genetic relation between proteid substances and 

 asparagin : in the reservoirs of reserve -materials proteid substances" only are 

 generally present ; at the commencement of the growth of the seedling, however, a 

 part at least of these is transformed into the easily soluble and diffusible asparagin, 

 which now passes into the younger buds, and is again transformed into proteid 

 substance. 



We may thus say, to put the matter simply, every growing part of the plant 



