298 FIRST FORMS OF VEGETATION. 
by magic, on a stale crust laid aside in a dark 
cupboard, attains its highest development, ripens 
and scatters its seeds, and perishes in a few days; 
the other sent forth its embryo shoots, in the 
primeval solitude many ages ago, and may yet wit- 
ness the revolution of many centuries ere it begins 
to decay. The largest stalk of the Bread-mould 
is no thicker than a pin, and may be half-a-line or 
the twentieth part of an inch in height ; the trunk 
of the Wellingtonia, like a huge church-tower, rises 
nearly 300 feet into the sky, and measures up- 
wards of a hundred feet in circumference. Why 
does this enormous difference exist? Why does 
the fungus live for a day and the tree for ages? 
Why does one seed produce a plant that has but 
a winter’s or at most a summer’s growth, and an- 
other grow into a plant which endures for more 
than three thousand years? They are both com- 
posed of the same materials—a collection and 
combination of simple cells; is it difference of 
form only that gives a longer term of life to the 
Wellingtonia than to the Bread-mould? Wecan- 
not by any search ascertain the source of life in 
the fresh seed, or account for the decay by which 
mature development is followed, and there is 
nothing in the structure of any plant, or indeed of 
any created thing, out of which the assigned limit 
of its life could be found. It is an impenetrable 
