THE CLEFT GRAFT 



grafting may continue into May, long after the tree 

 is in full leaf. However, do not cut back the tree 

 as severely as may be done in early springtime. 



The test of any method is in the result. Our 

 work being more successful when we cut out the 

 cleft, than when the limb was split to insert the 

 scion, we wished to know the reason for the better 

 result. 



Could it be possible that an improvement had 

 been made on this method of our grandfathers? 

 Securing a microscope of sufficient power to exam- 

 in the cell and cell structure of the plant, we found 

 an interesting field for study. The life zone of the 

 tree is in the ends of rootlets and branches, and 

 along the combium and sap wood. The dark heart 

 wood (duramen) is dead. Neither life nor circula- 

 tion is in it. The only benefit it is to the tree is to 

 give it strength. 



The outer thick bark of the tree is also dead; 

 and clinging to the inner bark it protects the tree 

 from heat and cold. The cambium of last year has 

 divided. The inner portion forms the last ring 

 growth of the wood, the outer becomes the inmost 

 layer of the bark. This year's cambium is thrusting 

 the double annual ring of cells between these two. 

 Tu every inch of the walnut there are more than 



[45] 



