BIRD'S EYE MAPLE.*
By W. J. BEAL, Agricultural College, Michigan.
THE wood of some trees of sugar maple, on removing
the bark, is found to be irregularly covered
with conical pits, which are more or less rounded at
the bottom. In many instances these pits are irregular
in outline; some are longest up and down the tree,
and not infrequently two or more are partially united.
The pits generally, though not always, have a depth
equal to the greatest diameter. The largest pits are
about a quarter of an inch in diameter, and vary in
size to the smallest, which can barely be seen with the
unaided eye. If the wood be split parallel with the
bark, the side of the stick so removed toward the
heart of the log will contain more or less conical projections,
such as come from the pits left in the counterpart
of the block.

On removing the bark, numerous small cones are displayed
on it, such as descended and just filled the pits
in the outer wood. By examining many radial sections.
one will frequently find instances where the
"bird's eye'' is just beginning, usually very small.
From this beginning the pits usually grow larger and
broader as we successively come to the 0lder wood.

Sometimes a pit runs of even size for many years;
sometimes it abruptly disappears as we view the wood
from that which is younger to that which is older, and
sometimes it becomes so broad that for an inch or
more it will be filled with bark. There may be some
interruptions where the bark disappears to reappear
after a few years. I have not been able to find any
trees showing "bird's eye" until they had acquired a
diameter of about three inches or more, and then the
marks were very small. Such young trees have all
been rather crooked and knotty, with irregular swellings
on the trunk, compressed in some places. A
smooth, straight, thrifty, healthy looking maple seldom
shows the ''bird's eye" to any extent. The
"bird's eye" marks may be abundant and well marked
on one side, or, perhaps, half or two-thirds of the circumference of the tree, and not be present on the rest
of the tree. They may be well shown all around the
lower part of a tree and partially disappear after a
few feet above. ''Bird's eye" is rarely found on the
limbs of a tree, and seldom shown on the trunk above
the lower limbs.

Mixed with the "bird's eye," or more or less independent
of it, will often be found "blisters" and
wanes and curls of all conceivable shapes. When such
wood is split open, parallel with the bark, it often presents
the appearance of folds of rich satin.
Where "bird's eye" maple is cut for market, most
of the maple trees of the forest show somewhere the
peculiarity to a greater or less extent, but, to be very
valuable, this peculiarity should be abundant and extend
clear around the trunk, and should extend far
enough up the trunk to furnish logs of sufficient
length to pay for marketing. These logs should be
destitute, or nearly so, of deep pits containing bark
or black streaks or shakes, and the thicker the sap
wood the better, as the dark colored or heart wood is
not salable.

At Vanderbilt, in Otsego County, Michigan, Mr.
John Berry says the best trees are found on the richest
land with clay subsoil, where, perhaps, one tree in
twenty-five is marketable, while on thinner soil the
trees are not so nice, and the proportion of marketable
trees may be one in forty.

They are shipped to Grand Rapids, New York, or to
England, or to some other place, where they are cut
into veneers.

No one can for certain pick out a good tree without
peeling or cutting off pieces of bark here and there in
several places on the tree. They often cut a pole to lean
against the trunk to enable them to make examinations
at a height of ten or fifteen feet. Many of the
logs are finally cut in lengths of two to eight feet,
thoroughly steamed, placed in a secure position to be
turned over and over against a long knife, which cuts
the veneer, which is the sixteenth of an inch or more
in thickness. This is dried and glued onto boards or
other cheap veneer and polished.

I have found several other species of trees showing
the “bird's eye" to a greater or less extent, usually only
affecting the tree in a slight degree, not sufficiently to
be used as veneer. Notably among these is the wood
of the beech and more rarely the wood of the hickory,
white ash, black cherry, American elm, Norway pine,
red maple and probably many other species. In some
cases which I have seen the depressions, instead of being
circular, are narrow and lengthened, sometimes half
an inch or more. In some specimens of sugar maple and
beech these long, narrow depressions run up and down
the tree; while in some observed in sugar maple they
extend transversely around the tree across the grain.
Occasionally the wood of sugar maple, beech, white
ash, and sometimes other species is regularly curly,
with the hollows and crests of the wanes well seen by
splitting the stick in radial section. These wanes vary
in length from three-eighths of an inch to a foot or
more from the crest of one wane to the crest of another.
In white ash and sugar maple and beech and rarely in
black walnut and other species the wanes occur irregularly on the wood, parallel with the bark. Such wood
is often used as a veneer, and in case of white ash it is
spoken of as "calico ash." 
Instead of small pits in the wood, as seen after removing
the bark of "bird's eye" maple, the wood of several
kinds of trees occasionally contains more or less protuberances or cones, while in the bark there is a corresponding pit. These have been seen on the red
maple, sugar maple, hickory, and American elm. In
some cases they appear to have come from adventitious
buds.
What causes "bird's eye" in maple, beech or other
wood?
The Indians of Northern Michigan have always attributed
it to damage done the trees by the pecking of
birds. I can find nothing in fact to warrant such an
opinion. 
* Read before the American Association, Toronto, 1889.

Occasionally maples are pecked by wood

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peckers, but such places do not become pits in the
wood, as is the case with "bird's eye."

In case of the beech, larvae of insects are sometimes
found in the inner bark extending to the cambium,
which they injure more or less. Sometimes the insect
kills a small spot of the cambium, and a 'black spot on
the wood and bark is the consequence . This spot is
sometimes enlarged in succeeding years by the action
of more insects and probably by the presence of fungi.
In some instances the insect seems to merely check the
growth of the cambium in the spot where it grow!", and
a pit appears in the wood at this place. In other cases
"bird's eye" beech seems to start without the aid of
any insect.
I have found no insects in the bark of the sugar
maple which cause the “bird's eye," yet when fresh
living specimens are examined in the summer, the
cambium at the bottom of the pits appears to be more
or less injured, showing minute spots of a yellowish
brown color, possibly started by some kind of
bacteria.