Suggestions for Laboratory Work to Precede Chapter Fifteen 



1. Grow seedlings on blotting paper or cotton, between two 

 glass plates. Keep the plates in one position until the roots are 

 2 or 3 inches long. Then set the plates at right angles to the 

 previous position. Note the change in the direction of growth of 

 primary and of secondary roots. 



2. Replace' the bottom of a cigar box with mosquito netting, 

 and place on the netting mustard or radish seeds that have pre- 

 viously been soaked in water. Then fill the box with wet moss or 

 cotton. Suspend the box so that the bottom rests at an angle of 

 45 degrees. Note the direction of growth of the roots as they 

 develop. Do they respond more to gravity or to moisture ? 



3. Study roots of floating or submerged plants. Note air 

 chambers. 



4. Study aerial roots of climbers like Boston ivy and trumpet 

 creeper. Study the prop roots of mature corn. 



5. Sketch and study roots of carrot, parsnip, or radish. Test 

 for starch. 



6. Sketch and study root nodules and roots of either clover or 

 beans. 



7. Study the arrangement of roots on a bulb or corm. Onion, 

 hyacinth, gladiolus, or crocus may be used. 



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