76 



GROWTH OF SEEDLINGS 



Method. Place the tube around the sprouting plant. 

 Then insert the vial and add the shot. Mark the vial at 

 the top of the tube and watch for upward 

 motion. Vigorous seedlings will often be able 

 to lift many times their own weight. 

 Conclusion. Same as preceding. 

 Suggestion. Compare seedlings of pea, bean, 

 squash, etc., to determine which are strongest. 



63. GROWTH 

 Object. To show the effect of light- 



Method. (a) Plant two potatoes in flower- 

 pots containing soil. Place one flowerpot in the 

 light and the other in the dark. Leave them for 

 several days. Then place them side by side. 

 Observe the growth of the plants node for node. 



(6) Plant potatoes, sweet potatoes, or beets in battery 

 jars or tumblers of water so that the lower surface dips 

 down into the water. Place some in darkness, some in 

 shade, and others in the strong sunlight. Result ? 



FIG. 23. 



64. GROWTH 



Object. To study the effect of light on direction of 

 growth of roots. 



Apparatus. Mustard seedlings, a cork disk, and a tumbler. 



Method. On a cork disk which has two or three perfora- 

 tions arrange some mustard seedlings so that their roots 

 pass through the holes. Float the cork disk in the glass of 

 water and set it in a light place, but not in the direct sun- 

 light. 



