Roots. 31 



make heavy, continuous lines running their full length. 

 Place the seedlings in moist sawdust, and after a day 

 notice whether the marks have separated at one portion 

 more than at another, and whether the continuous mark 

 has become broken at one portion more than at another. 

 What do these experiments teach as to the regions of 

 greatest elongation in roots? 



50. Examine the roots of trumpet creeper, which are 

 growing into some support. Do they appear to arise at a 

 definite place on the stem ? Do they grow directly toward 

 the support, or do they seem to have been uncertain as to 

 the proper direction to take? How deep do the roots pen- 

 etrate into the support ? If growing into a tree, do the 

 roots seem to have penetrated to a sufficient depth to take 

 sap from the tree ? The material for this study can be 

 secured at any time during the year. It is a good plan, 

 however, to gather it during the growing season and keep 

 it in jars of 2 fy formalin. 



51. Early in the spring, when the buds begin to swell, 

 cut off a grape vine about six inches from the ground, and 

 attach a long glass tube to the stump by means of a short 

 piece of rubber tube. Tie the glass tube to a support so 

 that it is held vertically. Keep note of the rapidity of the 

 rise of sap in the tube. 



52. Cut off a small branch of willow and place it in a 

 bottle of water. Set the bottle in a warm place and keep 

 the water replenished. Note from time to time whether 

 roots are forming in or above the water, and if so whether 

 they are formed in definite order. 



DISCUSSION. 



17. Functions of Roots. The roots, of plants have to 

 perform the functions of fixation, mechanical support, ab- 



