KNOTS AXD KNOT-BOLjaS 



21 



V. KNOTS AND KNOT-HOLES 



21. We have seen that some of the side 

 branches upon the little cherry tree (Fig. 15) died, 

 and that all the others will probably perish. Fig. 18 



Fig. 18. 



A dead branch and the mass of 

 healing tissues at its base. 



Fio. 19. 

 A knot-hole. 



shows a dead limb on an oak tree. The limb 

 became weak because the shade was too dense, 

 and because the branches above it took more than 

 their share of food. Finally, borers and fungi 

 attacked it, and it died. It rotted slowly away, 

 year by year its twigs fell, and finally a heavy 



