216 VEGETABLE PHYSIOLOGY 



assimilated by the living substance. This view is sup- 

 ported by observations made upon the utilisation of the 

 reserve stores of proteins found in seeds, which have been 

 found to give rise to similar amino-acids before being 

 transported from the site of storage. To this point we 

 shall return in a subsequent chapter. 



We cannot say either in what form proteins are tem- 

 porarily stored in the cells of their first formation. Pro- 

 bably, like starch, they are made indiffusible and so retained 

 in the cell. But whether they are thrown into a solid 

 form we do not know. If so, they are amorphous and are 

 hidden away in the substance of the protoplasm. They may 

 be kept in solution in the sap which saturates it. Different 

 forms of globulin and albumin have been found in the 

 cells in different regions. It is possible again that the 

 manufacture of protein may be only so great as to provide 

 for the needs of the cells in which such formation takes 

 place, together with the amount that can diffuse during 

 such manufacture, so that there may be no occasion for a 

 temporary storage there. 



The translocation of food has no very determinate 

 direction. On leaving the cells which are the seats of its 

 formation, its path is dependent on physical processes 

 taking place in different parts of the plant. We can study 

 it most simply by taking a special case, which as before 

 may conveniently be that of sugar. It may pass by 

 osmosis or diffusion from cell to cell or possibly it may 

 be picked out from the cell-sap by the protoplasm and 

 passed on to the vacuole of the next cell and so forward by 

 a kind of secretion. Whether by osmosis, diffusion, or 

 secretion, it is conducted through the parenchyma to 

 the fibro-vascular bundles, the bast of which we have 

 seen forms its principal path. These extend in complete 

 continuity throughout the plant, so that any travelling com- 

 pound can be transported from the leaves to the growing 

 points of the stem and root. So long as it is being used 

 by the protoplasm in these regions, the sap of the cells of 



