242 VEGETABLE PHYSIOLOGY 



increase in size, growing inwards into the protoplasm as 

 well as outwards into the vacuole, till they can be seen to 

 be in the form of grains embedded in the protoplasm, which 

 in consequence of their development assumes the appear- 

 ance of a coarse network. As this process continues, the 

 original grains growing in size, and new ones being con- 

 stantly formed, the original vacuoles become obliterated 

 and the cell swollen out by its own deposits (fig. 117). 

 While this mechanical process is going on chemical changes 

 also take place in the material secreted. The protoplasm 

 forms protein originally at the expense of the amido-acids, 

 sugars, &c., brought down to the cell, but the variety 



FIG. 117. CELL OF RIPE SEED or FIG. 118. CELL OF RICINUS SEED, 



LupinUS, FILLED WITH ALEURONE CONTAINING FlVE ALEUEONE 



GRAINS. GRAINS. 



originally constructed is not necessarily the same as that 

 subsequently stored. At first the grains are not soluble in 

 either 10 per cent, or saturated solutions of common salt. 

 Later on they can be dissolved by both of these fluids. 



The deposition of aleurone grains in the cell is thus, 

 like that of starch, a process of secretion carried out by the 

 protoplasm : a process, that is, of manufacture of the grain 

 by the latter, after it has been supplied with less highly 

 organised material. It is so constructed by the intervention 

 of the protoplasm itself, the grain growing at the apparent 

 expense of the substance of the latter. 



There is no doubt that the amorphous deposits of proteins 

 in the cells of fleshy roots and stems are due to a similar 

 process of secretion. 



