THE STOEAGE OF EESEEVE MATEEIALS 249 



When proteid 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. 118). They occur sometimes in the 

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

 119). In other cases they are found associated with a 

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



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 Leguminoscz. This is of interest 



FIG. 119. CELLS OF EMBRYO OF 

 PEA. (After Sachs.) 



a, aleurone grains ; st, starch grains. 



FIG. 120. CELLS OF SEED OF Lupi- 



miS, SHOWING COMMENCING FORMA- 

 TION OF ALEURONE GRAINS. (After 



Eendle.) 



a, nucleus ; &, vacuole ; c, originating 

 aleurone grain. 



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 suffi- 

 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. 120, c) ; these gradually 

 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 



