250 VEGETABLE PHYSIOLOGY 



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. 121). 

 While this mechanical process is going on chemical changes 

 also take place in the material secreted. The protoplasm 

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

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

 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. 



FIG. 121. CELL OF KIPE SEED OF FIG. 122. CELL OF RICINUS SEED, 



LupinUS, FILLED WITH ALEURONE CONTAINING FIVE ALEURONE 



GRAINS. GRAINS. 



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 interven- 

 tion 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 

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

 similar process of secretion. 



In many seeds, among which may be mentioned those 

 of the Castor-oil plant and the Brazil nut, the aleurone 

 grains possess a more complicated structure. Fig. 122 

 shows a section of one of the cells of a seed of the castor- 



