STOEA6E OP NOUKISHMBNT IN THE SEED. 



23 



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



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

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

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

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



32. Absorption of Starch from 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, 

 but they have lost their sharpness of 

 outline, and resemble somewhat the 

 "corroded" starch - grains of Indian 

 corn shown in Fig. 12. 



Cotyledons. — Examine with the 



Fig. 12. — Corroded Starch-Grains 

 from the Endosperm of the Kernel 

 of Sprouted Indian Corn. The 

 seedling over three inches high. 

 The middle starch-grain of the 

 lower row is uncorroded. 



• 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. 



