11 
one side, there are four on the other; and if you 
measure them off, provided the leaf has met with no 
accident, the one vein is as 
nearly as possible of the 
same size as the other. If 
you place the edges against 
each other, their little in¬ 
dentations will almost fit. In 
all plants there is the same 
remarkable correspondence 
between the opposite sides 
or the contiguous halves of 
the same leaf. More com¬ 
plicated examples are easily 
found. You have a leaf 
with fifteen divisions on each 
side—in all thirty. In all the contiguous divisions of 
the same leaf there will be thirty also. But the 
number may diminish to twenty; and then, if there 
are twenty on the one side there are twenty on the 
other, or it may be reduced to ten on the one side 
and then there will be ten on the other. In all 
such cases symmetry is in no degree impaired, what¬ 
ever may be the amount of complication in the 
structure of the leaf. Nothing of this kind is more 
elaborate than what we find in tree Ferns. Myriads of 
minute divisions contribute to form the general leaf; 
of those divisions every one of the larger is exactly 
like its neighbour; they balance each other. As 
such leaves diminish in length, the size of their 
divisions also diminishes, and the parts belonging to 
the internal structure are also reduced in the same 
ratio; so that the symmetry or balance of parts is 
still maintained with much exactness. 
a G 
