STORAGE OF FOOD IN THE SEED 



19 



Pulp scraped from a potato, that from a canna rootstock, wheat 

 flour, the finely powdered starch sold under the commercial name of 

 "cornstarch" for cooking, oat- 

 meal, and buckwheat finely pow- 

 dered in a mortar, will furnish 

 excellent examples of the shape 

 and markings of starch grains. 

 Sketch all of the kinds exam- 

 ined, taking pains to bring out 

 the markings. 1 Compare the 

 sketches with Figs. 7 and 8. 



With a medicine-dropper or a 

 very small pipette run in a drop FIG. 7. Canna starch. (Magnified 

 of iodine solution under one edge 



of the cover-glass, at the same time withdrawing a little water from 

 the margin opposite by touching to it a bit of blotting paper. 



FIG. 8. Section through Exterior Part of a Grain of Wheat. 



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

 sch, layers of hull next to seed-coats ; br, n, seed-coats ; Kl, layer containing 

 proteid grains ; st, cells of the endosperm filled with starch. (Greatly magnified.) 



1 The markings will be seen more distinctly if care is taken not to admit 

 too much light to the object. Rotate the diaphragm beneath the stage of the 

 microscope, or otherwise regulate the supply of light, until the opening is 

 found which gives the best effect. 



