is about 80 feet below the surface. My gardener tells me that the tree
has been "bleeding" at about the same rate for fourteen of the fifteen
days, the first day the branch becoming only somewhat damp. During the
earlier part of that time we had frosts at night, and sunshine, but with
extremely cold winds, during the days. At one time the exuding sap
gave, I am told by two different observers, icicles a foot long. A much
warmer, almost summer, temperature has prevailed during the past three
days, and no wind. This morning the temperature of the sap as it escaped
was constant at 52 deg. F., while that of the surrounding air was varying
considerably.

The collected sap was a clear, bright, water-like fluid. After a pint
had stood aside for twelve hours, there was the merest trace of a
sediment at the bottom of the vessel. The microscope showed this to
consist of parenchymatous cells, with here and there a group of
the wheel-like or radiating cells which botanists, I think, term
sphere-crystals. The sap was slightly heavier than water, in the
proportion of 1,005 to 1,000. It had a faintly sweet taste and a very
slight aromatic odor.

Chemical analysis showed that this sap consisted of 99 parts of pure
water with 1 part of dissolved solid matter. Eleven-twelfths of the
latter were sugar.

That the birch readily yields its sap when the wood is wounded is well
known. Philipps, quoted by Sowerby, says:

"Even afflictive birch,
Cursed by unlettered youth, distills,
A limpid current from her wounded bark,