IIL] EARLY FORM OF. 25 



viewed in the log, to be fit for any purpose where 

 straight timber was required. 



It is, therefore, clear that trees .do not change or 

 alter their form while young, except in a very slight 

 degree ; they appear rather to assume the fairer and more 

 even growth later on, and very gradually. It may pos- 

 sibly be brought about by the matter which forms the 

 zones of each succeeding year's growth contributing to 

 one part a greater and to another a lesser substance of 

 woody layer, as required to develop the fairer growth 

 seen in the matured tree referred to. And hence, if we 

 take a perfectly straight tree, and cut it through the 

 middle longitudinally, we are pretty sure to see the 

 pith running snake-like along its entire length (Fig. 7). 

 Therefore, in timber having much heart-shake, there is 

 certain to be considerable waste in its conversion, espe- 

 cially if we wish to reduce the log into plank and 

 board. 



