358 ^ OBSERVATIONS ON 
height only by their annual upper shoot. But my neigh- 
bour over the way, whose occupation confines him to one 
spot, assures me that trees are expanded and raised in the 
lower parts also. The reason that he gives is this: the 
point of one of my firs began for the first time to peer over 
an opposite roof at the beginning of summer ; but before 
the growing season was over, the whole shoot of the year, 
and three or four joints of the body beside, became visible 
to him as he sits on his form in his shop. According to 
this supposition, a tree may advance in height consider- 
ably, though the summer shoot should be destroyed every 
year. 
FLOWING OF SAP. 
If the bough of a vine is cut late in the spring, just before 
the shoots push out, it will bleed considerably; but after 
the leaf is out, any part may be taken off without the least 
inconvenience. So oaks may be barked while the leaf is 
budding ; but as soon as they are expanded, the bark will 
no longer part from the wood, because the sap that lubri- 
cates the bark and makes it part, is evaporated off through 
the leaves. 
RENOVATION OF LEAVES. 
When oaks are quite stripped of their leaves by chafers, 
they are clothed again soon after Midsummer with a beautiful 
foliage ; but beeches, horse-chestnuts, and maples, once 
defaced by those insects, never recover their beauty again 
for the whole season. 
ASH-TREES. 
Many ash-trees bear loads of keys every year, others never 
seem to bear any at all. The prolific ones are naked of 
leaves and unsightly; those that are sterile abound in 
foliage^ and carry their verdure a long while, and are 
pleasing objects. 
BEECH. 
Beeches love to grow in crowded situations, and will in- 
sinuate themselves through the thickest covert, so as to 
