Of Vegetation . $ 3 7 
expands) by the fponginefs of the pith, 
without the help of valves. For ’tis very pro- 
bable that the particles of water, which 
immediately adhere to, and are ftrongly im. 
bibed into, and attracted by every fibre of 
the fpongy pith, will fuffer fome degree 
of expanficn before they can be detached 
by the fun’s warmth from each attracting 
fibre, and confequently the mafs of fpongy 
fibres, of which the pith confifts, muft there- 
by be extended. 
And that the pith may be the more fer- 
Viceable for this purpofe, nature has provi- 
ded in mod fhoots a ftrong partition at everyt, 
knot, which partitions ferve not only as 
plinths, or abutments for the dilating pith 
to exert its force on, but alfo to prevent the 
rarifiedfap’stoo free retreat from the pith, as 
well as for the (hooting forth of branches, 
leaves, and fruit. 
But a dilating fpongy fubftance, by equally 
expanding it felf every way, would not pro- 
duce an oblong Ihoot, but rather a globofe 
one, like an Apple ; to prevent which in- 
convenience we may obferve, that nature 
has provided feverai Diaphragms, befides 
thofe at each knot, which are placed at fmall 
difiances acrofs the pith ; thereby preventing 
Z ics 
