12 
18. Another leaf has cei’tain projecting ribs: two 
lines of projections on each side of the mid-rib. Now 
those projections correspond exactly the one to the 
other, as far as they go. At last they wear out; 
but there is no loss of symmetry in consequence of 
diminished force in the formative powers of the plant. 
19. Wherever we look the same pervading rule is 
found. Such exceptions as may be observed are 
apparent, not real. In fact the growth of a plant 
is a system of equipoise, and the result is symmetry. 
The way however in which symmetry is manifested 
much varies. 
20. In the branch of a sycamore tree the buds are 
formed in opposite pairs, right and left., fore and 
aft,—right and left, fore 
and aft, — and so on ; 
and such is the constant 
rule, any apparent de¬ 
parture arising from ac¬ 
cidents to which plants 
are peculiarly subject, 
but which ought no more 
to be taken into account 
in considering what na¬ 
ture intends, than the 
occasional mutilations 
by which the human 
frame is disfigured. 
21. In another tree, 
the Linden for example, 
symmetry is displayed 
in a different way. The 
buds are no longer oppo¬ 
site, but alteniate; one 
on the left, another on the right, and so on, right 
