IV.] HEART-SHAKE. 
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). 
* 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. 
