THE FLOWER 



137 



the cell walls, and, being visible through the more or less translucent 

 pericarp, gives the grain its characteristic tint. 



Ultimately, the radial walls of this inner layer are disorganised or 



FIG. 109. Transverse sections illustrating the changes in the inner layer of the pericarp, 

 the integuments, and nucellus during the growth and ripening of the grain ( x 270). a, 

 " Cross layer " (p. 8) ; b, inner epidermis of the pericarp ; c, outer, d, inner integument 

 of the ovule ; e, epidermis of the nucellus ; /, cells of the nucellus ; g, aleuron layer. 



dissolved (6, 'd, Fig. 109), and as the result of the shrinkage which occurs 

 during the final stages of drying and ripening of the grain the inner and 

 outer walls are crushed together. The two collapsed layers representing 

 the inner integument persist as the testa of the seed. 



