THE STOEAGE OF KESEKVE MATEKIALS 241 



cases, as in fleshy roots, the protein may be dispersed in 

 amorphous form in the substance of the protoplasm. 



When protein is stored in the condition of granules 

 these are known as aleurone grains. Like starch grains 

 they may be deposited all through the substance of the 

 seed, or they may occupy definite layers, as they do in the 

 cereal grasses (fig. 114). They occur sometimes in the same 

 cells as do starch grains, as in the pea or bean (fig. 115). 

 In other cases they are found associated with a quantity 

 of oil, as in the seed of the castor-oil plant. 



FIG. 115. CELLS OP EMBRYO OF 



PEA. (After Sachs.) 

 a, aleurone grains ; st, starch grains. 



FIG. 116. CELLS OF SEED 



OlfLupimiS, SHOWING COM- 

 MENCING FORMATION o 

 ALEURONE GRAINS. (After 

 Rendle.) 



a, nucleus ; 6, vacuole ; c, 

 originating aleurone grain. 



An instance of the occurrence of aleurone grains of 

 some size, but yet of fairly simple composition, is afforded 

 by the Lupin, one of the Leguminosce. This is of interest 

 especially because the origin of the grain can be observed 

 and its development traced. In this seed the aleurone 

 grains begin to be formed at a very early period of the 

 development, just as the growth of the embryo is sufn 

 ciently advanced to swell out the seed-coat. The cells of 

 the embryo at that period show the protoplasm not sufficient 

 in amount to fill each cell, so that a number of spaces or 

 vacuoles occur, filled with sap. At certain places small 

 projections from the protoplasm may be noticed which are 

 of spherical or ovoid shape (fig. 116, c) ; these gradually 



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