LABORATORY EXERCISES 57 



Pulverize the resin; melt all the materials together. Drop the ball 

 of cotton into the melted wax. Remove in about five minutes, and 

 you will have waxed string ready for making root grafts. Pour the wax 

 into cold water. Grease the hands and pull and work the wax until 

 it becomes of a straw color. 



14. Cambium Layer. 



Materials. Twigs several years old taken from any tree. Make a 

 drawing of a cross-section of the twig, and indicate: (1) The pith; 

 (2) annual rings; (3) cambium layer; (4) bark. The cambium layer 

 is the layer between the wood and the bark. It is this layer that breaks 

 apart when the bark is removed. Why is the bark more easily removed 

 in summer than in winter? How old is the twig? Why is there a ring 

 at the close of each year's growth? Is the wood in the inner or the outer 

 part of the ring the harder? 



15. To Make a Root Graft. 



Materials. Waxed string prepared in No. 13. Seedling apple 

 trees one or two years old. Smooth, one-year-old twigs from apple 

 trees of the desired variety. 



Let each student make about twenty-five or more root grafts ac- 

 cording to directions (page 45). These may be taken home to be 

 planted. They should be packed in sand and kept moist and cool until 

 spring. The school can raise its own seedling apples, peaches, etc., 

 or may get students to raise them. 



16. To Bud a Tree. 



Materials. Raffia, knives, growing trees. If possible, have impor- 

 tant trees of the region. 



Cut the buds as shown in Fig. 21. Make the T-shaped cut through 

 the bark of the tree. Lift the bark carefully and insert the bud. Tie 

 firmly with raffia. 



17. To Top-graft a Tree. 



Materials. Saw, knife, chisel, hammer, grafting wax, apple trees 

 or other trees. 



Perform the operation as directed (page 46). If possible, this 

 should be done on a tree; but limbs of trees may be used in the labora- 

 tory to teach the method if outdoor work cannot be given. 



18. To Make Hard Wood Cuttings. 



Materials. Stems of grapes, currants, willows, or other woody 

 plants of the region. 



