338 THE BIOLOGY OF THE PLANT 



it in shape, size, and structure with the cau- 

 licle. 

 Make sketches of the bean, illustrating all of these 

 structures. 



II. — Examine in like manner seeds of the watermelon, 



cucumber, pea, oak, maple, and corn. Compare 



them with the bean in all respects and explain 



the differences. 



Draw each kind of seed examined to show its structure. 



What are the structural differences between a seed 



and a spore? 



III. — Some of the Chemical Contents of Dry Seeds. 



a. Tests for starch. 



1. Fill a test-tube one-third full of water, add a 



pinch of dry corn-starch, and shake the tube. 

 Does the starch dissolve? Heat the tube to 

 the boiling-point over the flame of an alcohol 

 lamp, keeping the tube agitated during the 

 process to keep the starch from settling to the 

 bottom of the tube. What change takes place? 

 Explain. Set the tube aside to let the starch 

 cool. 



2. Fill another tube one -third full of water, and 



add a drop of iodine. What result ? Explain. 



3. Add a drop of iodine to the cold starch in the 



first test-tube and shake the tube. What re- 

 sult ? Compare with 2. To what is the dif- 

 ference in results due ? 



4. Peel the testa from several dry beans, break the 



beans into small pieces, place the pieces in a 

 test-tube containing water, and boil them for 

 several minutes. Then cool the tube and di- 



