III.] 
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. j). 
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. 
