SUPPOSED CAUSES. 95 
explanations of this subject also; but we must 
confess it is anything but clear even now. One 
eminent French Botanist tells us, it is because 
certain delicate little tubes become suddenly 
broken at the stalk of the leaf, so cutting 
off the communication between the leaf and 
the branch; and then, of course, it dies and 
falls off. Another tells us, that the poor leaf 
dies of overwork: it evaporates so much water, 
that the solid impurities left behind fill and 
choke up all its pores, so that by the Autumn 
it can do no more work of this kind, and there- 
fore dies and drops off. Dr. Lindley seems to 
think, that it is due to both these causes com- 
bined. 
Though ignorant of the cause of these changes, 
we may derive instruction from their solemn tones 
of warning! ‘ We all do fade as doth a leaf!” 
Just as after a few swift months of Summer, the 
declining year tinges even the freshest forest leaf 
with its under-tones of colour,— sure token of 
advancing decay and death,—so the grave linea- 
ments of age come upon the freshest and fairest 
countenance, and carry the same lesson with 
them: the day of life is nearly spent, the night is 
