392 TEXTBOOK OP BOTANY 



3. Remove the seed coat. Can you see that it is composed of 

 more than one layer? Just within is the thin, green, papery en- 

 dosperm. Remove this. All that now remains belongs to the 

 embryo. 



4. Carefully cdt away one of the thick seed leaves of the embryo. 

 There remains the second seed leaf, and attached to it are the radicle 

 and plumule. Which of these two is larger? Which is turned 

 toward the micropyle? 



5. Examine the plumule with a hand lens. It can be studied 

 better in seeds that have been soaked for two or three days. How 

 many small leaves does it bear ? 



6. Cut another seed' lengthwise in such a way that each seed 

 leaf will be cut through the middle. Draw one of the cut surfaces, 

 showing the seed coat, endosperm, seed leaves, plrunule, and 

 radicle. 



7. Plant some seeds, which have been soaked over night in cold 

 water, an inch below the surface of moist sand or sawdust. After 

 the first two or three days pull up a seed or two each day and study 

 the way in which they germinate. 



8. Where does the seed coat crack when the seed germinates? 

 Which part of the embryo pushes out first? Which way does it 

 turn ? Study the growth of the embryo into a seedling ; what 

 changes take place in each part of the embryo? Study the way 

 in which the seed coat is finally pushed off. 



9. Draw in outline three young seedlings at different stages in 

 their development. 



10. Sow some cucumber seeds in moist sand. After a seedhng 

 has developed one or two secondary leaves, wash off the sand or 

 sawdust very carefully from the root system. To what parts of the 

 roots does the sand or sawdust stick most closely ? Why ? Can 

 you tell by examination where the stem ends and the root begins ? 



11. Can you distinguish the primary root from the branch roots ? 

 Do the latter also branch? Lay the plant down, spread out the 

 roots as flat as possible, and sketch the root system. 



12. Study the root hairs of a very young seedling from a seed 

 germinated between pieces of moist filter paper or blotting paper. 

 Can you see the hairs with the naked eye ? Examine them with a 

 hand lens. On what part of the root do they grow? 



