IV.] 



HEART-SHAKE. 



29 



very scant, or perhaps to trees unequally balanced in 

 their branches, if grown in the open. There is some- 

 thing like evidence of this twisting in the spiral turns of 

 grain noticed in many trees.* The heart-shakes are 

 equally disadvantageous, if, indeed, they are not more 



FIG. 9. 



so, when they cross each other at the pith, and open to 

 the full diameter of the tree, splitting it into four seg- 

 ments. This form of the defect is very conspicuous in 

 the Green-heart timber (Fig. 10). 



FIG. 10. 



* This spiral growth is common in the Turkey Box tree ; it is also 

 frequently seen in the Fir and Pine species, and occasionally in other 

 woods. 



