222 VEGETABLE PHYSIOLOGY 



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 

 kinds 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. We are not sure whether the 

 process of their formation is a continuous one, or is inhibited 

 at night. 



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. We are not familiar 

 with the physical process of its passage from cell to cell : 

 it is unlikely that osmosis causes it to pass so regularly, and 

 diffusion is apparently not sufficiently rapid to explain it : 

 possibly it may be picked out from the cell-sap by the proto- 

 plasm and passed on to the vacuole of the next cell and 

 so forward by a kind of secretion. We know, however, 

 that it is conducted through the parenchyma to the 

 nbro-vascular bundles, the bast of which, we have seen, 

 forms its principal path. These extend in complete con- 

 tinuity throughout the plant, so that any travelling com- 

 pound can be transported from the leaves to the growing 



