414 TEXTBOOK OF BOTANY 



How does the ovary change as it grows into a fruit ? What changes 

 take place in the cob ? In the husks ? 



9. What is the shape of a ripe com kernel? What differences 

 do you notice between its two broad sides? Can you find where 

 the silk was attached ? 



10. Place kernels in lukewarm water and leave them over night. 

 How have they been changed by the soaking? Peel off the seed 

 coat and the fruit coat, which have grown together. Inside find 

 the endosperm and the embryo. Which makes up the larger part 

 of the kernel ? On which side of the kernel is the embryo located ? 

 Separate the embryo from the endosperm. Notice that the embryo 

 is surrounded by the thick seed leaf. 



11. With a sharp knife split another soaked kernel lengthwise 

 so as to cut through the middle of the embryo. With the aid of a 

 hand lens, find the following parts of the embryo ; seed leaf, radicle, 

 plumule, secondary leaves. Draw the cut surface so as to show 

 these parts as well as the endosperm and the outer coat of the 

 kernel. 



12. Study the germination of the com seed as directed in §§ 7 

 and 8 of the directions for the study of the squash or pumpkin seed. 

 Notice especially what happens to the seed leaf, the first secondary 

 leaf, and the later leaves ; also how, after the primary root has 

 begun to grow, other roots start. Where do they grow from? 

 Draw in outline three seedlings of different ages. 



13. After a seedling has developed one or two ordinary leaves, 

 pull it up and wash its roots very carefully. To what parts of the 

 root system does the sand or sawdust stick most closely? 'UTiy? 

 Is the kernel still attached to the young plant ? If so, what holds 

 it in place ? 



14. Compare ears of flint, dent, sweet, and pop com. How do 

 they differ ? How do their kernels differ ? 



15. Make a list of the varieties of corn that are grown in your 

 neighborhood. How do they differ? To what class (flint, dent, 

 sweet, or pop) does each variety belong? What advantages does 

 each variety have ? 



16. Compare varieties of corn whose kernels are of different 

 colors (yellow, red, black, etc.). In what part of the kernel is the 

 color located ? 



