94 LABORATORY EXERCISES 



;green? In which do they remain attached? Describe ail the 

 changes that the cotyledons undergo. Why do they change? 



e. Examine the soaked seeds of b that were not planted. 

 How is the testa of each affected by the soaking? Look for 

 the scar (hilum) showing the place at which the seed was 

 attached. With a knife cut through the testa; do it carefully, 

 so as not to mutilate the plumule or the hypocotyl. In the 

 beans you can cut on the curved edge. Pick off the testa, 

 and spread the cotyledons apart. Describe what you find in 

 each case. 



In the corn look for the single cotyledon. After removing 

 the testa cut through the kernel lengthwise, at right angles 

 with the flat surfaces. Describe all you find. 



EXERCISE 89 

 MATERIALS PRESENT IN PLANTS 



Apparatus and Materials. Scissors or a knife, bottle, saucer or 

 evaporating dish, iron dish, glass cover, burner, test tube, white 

 writing paper, grass or other green leaves, alcohol, slaked lime or 

 soda-lime, flour, starch, iodine solution, corn meal, potato, radish, lard 

 or linseed oil, benzine, ground flax seed. 



a. Chlorophyll. With scissors or a knife cut up very finely 

 a handful of grass, spinach, parsley, or other green leaves. If 

 you have a mortar and pestle, you can crush the material also. 

 Put the material into a bottle, and cover it with alcohol. Let 

 the bottle stand, stoppered, for an hour or two, and note the 

 colored solution that is produced. 



Pour out a few cubic centimeters of the solution into a 

 saucer, and let the alcohol evaporate without heating it. 

 Note the green chlorophyll that remains. If you wished to 

 prepare a green "ice," how could you get a harmless coloring- 

 material? 



