EXERCISES WITH ROOTS 29 



a manner that tlicy will point in various directions. Examine at tlu- 

 end of 24 hours and again at the end of 48 houra Note the direction of 

 growth, the point at which curving begins and where the curvature is 

 greatest as indicated by the marks and the point at which the greatest 

 growth occurs. 



5. Examine the root system of a growing bean, castqr bean, or sun- 

 Hower. Note the tap root, the mode of branching, the location of oldest 

 and youngest branches, size and shape of tap root and branches. Make 

 drawings or diagrams. 



6. Examine the root system of growing corn, wheat or oats. Com- 

 pare the root system with tliat in Ex. 5. Make drawings or diagrams. 



7. Examine the root system of a growing beet, turnip or radish. 

 Note the tap root and its branches Compare with that in Ex. 5. Make 

 drawings or diagrams. 



8. Examine the root system of tlie dahlia or sweet potato. Compare 

 with that in Ex. 7. Make drawings or diagrams. 



9. Examine the root system of English ivy or some other plant or 

 plants in which the roots serve for climbing. Note their location, branch- 

 ings and general character. Make drawings or diagrams. 



10. Region for Root-hairs. — Sprout a niunber of grains of corn, 

 okra, radisli seed, clover seed, or white mustard, between wet blotting 

 paper until the roots are abouti one and one-half inches in length. Note 

 the region on which the root-hairs occur. Examine the root-hairs under 

 a compound microscope, or strong hand lens. 



11. Soil Held by Root-hairs. — Plant seeds in fine, sandy soil. After 

 two weeks wet the soil thoroughly and very gently remove the plants. 

 Note the manner in which the soil is held by the root hairs. 



12. Roots from Willow Twigs. — Ctit a niunber of willow twigs about 

 twelve inches in length and put in a jar of water so that about half the 

 length will be covered. Put part of them' upside-down. Use an earthen 

 jar or a glass jar covered with black paper so as to exclude the light. 

 Examine from time to time and note the formation of roots. Where are 

 they located and what is the direction of growth? 



13. Osmosis with a Thistle Tube. — Make an artificial root-hair 

 by covering the large end of a thistle tube with an animal or plant mem- 

 brane, piece of intestine (sausage covering) or bladder, fill the bulb with 

 a thick syrup (mola.^ses) and invert in a jar of water so that the two 

 fluids stand at the same level. Examine after a few* hours^ and note the 

 rise of the fluid in the tube. This passing of a fluid of less density through 

 an animal membrane into a fluid of greater density is called osmosis. 

 (Pages 112 and 11.3.) 



14. Osmosis with an Egg. — Remove the shell without breaking the 

 skin from the large end of an egg over an area about the size of a dime. 

 In the same manner remove a small bit of shell from the small end over 



