THE STORAGE OF RESERVE MATERIALS 235 
When protein is stored in the condition of granules 
these are known as alewrone 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. 
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 Leguminose. This is of interest 
Fic. 116.—CELLSs oF sEED oF Lupi- 
nus, SHOWING COMMENCING FORMA- 
TION OF ALEURONE GRAINS. (After 
Fic. 115.—CELLS OF EMBRYO OF Rendle.) 
Pea, (After Sachs.) a, nucleus; b, vacuole; ¢, originating 
ua, aleurone grains ; st, starch grains. 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. 116, 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 
