"No," replied Uncle Robert, "for the hole they make is only about an
inch across. If they were to cut all around the tree, you see, it would
stop the running of the sap and kill the tree."

"That is called girdling," said Mr. Leonard. "They used to clear off
hundreds of acres of land in that way when this country was first
settled. Instead of cutting down the trees, they girdled them near the
ground. In a very short time they died, because they could get no food
from the earth. The dead trees lost their strength, and a strong wind
would blow them over. Then they were piled up and burned."

"How do you know when a tree is dying?" asked Uncle Robert.

"The leaves turn yellow," said Donald.

"But the leaves turn yellow in the fall," said Frank, "and the trees do
not die."

"The leaves of my spruce don't turn yellow in the fall," said Donald.
"They stay green all winter."

"What makes the leaves green?" asked Uncle Robert.

No one answered.

"What is the color of the potato sprouts in the cellar?"

"Yellow," said Susie.