STORAGE OP NOURISHMENT IN THE SEED. 



23 



in the seeds in bulk, but tliat it is inclosed in little chambers or 

 cellsA 



Fig. 11. — Section through Exterior Part of a Grain of Wheat, 

 c, cuticle or outer layer of bran ; ep, epidermis ; m, layer beneath epidermis ; qw, sch, 

 layers of hull next to true seed-coats ; br, n, seed-coats ; A7, layer containing 

 grains of proteid material ; si, cells of the albumen, filled with starch. 



32. Absorption of Starch from the Cotyledons. — Examiae with the 

 microscope, using a medium power, 

 soaked beans and the cotyledons from 

 seedlings that have been growing for 

 three or four weeks. Stain the sec- 

 tions with iodine solution, and notice 

 how completely the clusters of starch- 

 grains that filled most of the cells of the 

 unsprouted cotyledons have disappeared 

 from the shriveled cotyledons of the 

 seedlings. A few grains may be left, Fig. 12. —Corroded starch-Grains 

 but they have lost their sharpness of from the Endosperm of the Kernel 

 , , . - , , , i i, of Sprouted Indian Corn. The 



outhne, and resemble somewhat the ^^^^^^^ <,^^, t^,^^ i^^i^^^ ^.^^_ 



"corroded" starch - grains of _ Indian The middle starch-grain of the 

 corn shown in Fig. 12. lower row is uncorroded. 



1 The teacher will do well to sketch with the camera lucida a few divisions of the 

 stage-micrometer and some cells of the seed, with contained starch-grains, on a piece 

 of cardboard that may be passed round the class to give a precise idea of the actual 

 and the apparent size of the objects examined. 



