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 saturatesit. 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 
