GROWTH OF BARK, 29 
27. In a moderate sized branch or stem of a Maple, 
or Plane, cut across very smoothly, may be seen, in 
the centre, as represented at f. 5. a small quantity of 
pith, surrounded by a number of rings or narrow 
layers of wood, each layer haying been the growth 
of one year; these are surrounded by bark (@.). 
From the centre may be seen a number of fine lines, 
passing to the bark; these are intended to keep up a 
communication between the pith and the bark, and 
may be called pith-rays. 
OF THE BARK, 
28. The Bark grows in a different way to the wood; 
each year as the new wood is formed outside the old 
or last year’s wood, some new bark is also formed along 
with it, so that in process of time, the older bark, or 
that which was formed at an early period, becomes 
remoyed further from the wood, against or upon which 
it was placed. That is to say, the wood of this year, 
has some bark lying upon it, but next year, a layer of 
new wood, and a layer of bark will grow up or be 
formed between it and its bark; and consequently the 
old bark will be pushed outwards, to make room for the 
new. ‘This may be seen at f. 3. in which 0. is the bark 
of as many years growth as there is wood; and at 1. 
is seen that bark which covered the wood of the first 
year, marked w. 1.; 2. that which belonged to the 
second year’s wood, and so on; at ¢. is deposited what 
will form new wood, on w. 4. and new bark on 0. 4. 
So that the wood and bark of the fourth, will be 
separated from each other. 
