of autumn, we shall find that the leaves toward the tip of the 
branch are frequently smaller than those below them, and that 
the distance between the places of leaf attachment near the tip 
has become shorter. 
At the very tip the stem has practically ceased to elongate, 
and a very great change has taken place in the shape of the leaves 
and the way they grow. In place of the large, beautiful foliage 
leaves of the horsechestnut, for example, we shall find stiff, brown 
scales, covered with a sticky substance, and closing in together. 
These scales, and the newly formed parts of the stems which 
they enclose, together constitute a bud. 
Why it is that scales appear instead of foliage leaves is one 
of the many mysteries of plants. No one really understands 
this. How it is that the scales fold together seems, at first 
thought, also difficult to understand, since plants have no 
muscles with which to move their parts. It is, however, easier 
to explain this, at least in part. It is because the modified leaf, 
or bud-scale, does not grow equally fast on opposite sides. The 
under (or outer) side elongates more rapidty than the upper (or 
inner) side, and this is why the scales close in together. But 
what it is that causes the under side of the bud-scale to grow 
faster than the upper side we do not understand. There are 
many theories about the matter, but the fact is that no one at 
present really knows. Finally, by the time the bud is made and 
the foliage leaves have fallen off, winter comes on, and prac- 
tically all growth and all food-making cease. Buds are formed, 
not only at the tips of the main stem and its branches, but also 
in the axil of every foliage-leaf. 
How is it that the bud protects its tender parts during winter? 
Inside the bud-scales many buds, and notably those of the horse- 
chestnut, have a quantity of wool-like material closely packed in 
around the embryonic leaves. It has many times been stated, 
even in books on nature study and botany, that the bud-scales 
and the woolly substance protect the tender parts from freezing. 
It is very easy, however, to demonstrate that this is not correct, 
for if anyone will cut into any bud on a winter’s day when the 
thermometer is below the freezing point, he will find much ice 
