SEEDS AND SEEDLINGS 113 



cover as little as possible. Shake it around thoroughly and look to see 

 what its condition is ? What does this show ? 



Light a splinter of wood and slide the cover of the other jar to one side 

 enough to admit it. Does it burn in the jar ? This shows what ? 



1 6. Turn over boards or stones in the field to find a plant growing partly 

 under the board, partly out in the light. What is the color of the covered- 

 up portion ? What is the usual color of all plant leaves ? Do you know 

 why ? Take a blanched leaf and a green leaf from the plant you have found. 

 Notch one so you can tell them apart. Put both into 70 per cent alcohol 

 in a small covered dish for a few hours, until the green color is gone from the 

 green leaf. Warm the alcohol if necessary. (Be careful; it burns readily.) 

 Pour off the alcohol, wash with water, and stain with iodine solution. 

 State your conclusion. 



Read up now on the process of food manufacture in the plant and write 

 a statement of what occurs in the leaf as sugar, for instance, is made. 

 Refer to the experiments as needed to illustrate the steps. What part 

 does light play in the process? the chlorophyll? Draw on the opposite 

 page a seedling plant to show that it is sensitive to the influence of light; 

 also a "leaf mosaic." 



17. Set a piece of cardboard vertically in a flowerpot. Fill one side 

 of the pot with sand and the other with well-manured earth. Then 

 remove the cardboard partition and plant on the midline between the 

 two sorts of soil a few oat or sunflower seeds. When the seedlings are 

 well up displaying several leaves, root up carefully and see where the 

 roots are. 



Roots ordinarily grow in response to Do you 



realize how remarkable it is that two points so close together as the stem 

 and root in the embryo should start one up and the other down under 



identical conditions ? The roots in the experiments grow in 



response to 



(Does the term you fill in here explain the phenomenon or name it ?) 



Work. Does a plant work? If so, where does it get the energy to 

 accomplish it? The partial answer has been given above. This experi- 

 ment will make clear another source of energy. 



1 8. Put a layer of moist, crumpled, filter paper or blotting paper in 

 each of two pint fruit jars. Add a level teaspoonful of radish or clover 

 seed. Put in another layer of paper and more seed in each, then moisten 

 and screw on the covers. Let stand three or four days, until the seeds 

 are plainly germinated. Introduce carefully a lighted splinter of wood 

 into one jar, sliding the cover slightly to one side for the purpose. What 

 happens? Try the limewater test for carbon dioxide on the contents of 



