236 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. 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 
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. 
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Wax 
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Fic. 117.—CrELL OF RIPE SEED OF Fie, 118.—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 
proteins 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. 118 
shows a section of one of the cells of a seed of the castor- 
